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/ith this program it is possible for the user to design basic structural parts such as slab

beam column and footing. lso the program is based on the merican Concrete Institute

Code. ,he ultimate goal of this program is that users can analy-e their own designs using

this program and determine structural proportions of their design idea.

,he rapid development of the computer in the last decade has resulted in rapid adoption

of Computer *tructural esign *oftware that has now replaced the manual computation.

,his has greatly reduced the comple%ity of the analysis and design process as well as

reducing the amount of time re$uired to finish a pro0ect.

1.2 Statement of the Study

,his study involves the development of design software for #eam Column 'ooting and

*taircase.

1.3 Objective of the Study

1. ,o ma&e the design Calculation simple easier and rapid.

. ,o get &nowledge and to use the merican Concrete Institute Code (CI 21834).

2. ,o develop a software for the design of several structural element (#eam Column

*tair 'ooting) according to the provision 5 procedure of the merican Concrete

Institute Code (CI 21834).

6. ,o get economical section without any arithmetic mista&es.

1.4 Computer oft!are

*oftware is a program that enables a computer to perform a specific tas& as opposed to

the physical components of the system (hardware).

,his includes application software such as a word processor which enables a user to

perform a tas& and system software such as an operating system which enables other

software to run properly by interfacing with hardware and with other software. 7ractical

computer systems divide software into three ma0or classes system software

programming software and application software although the distinction is arbitrary and

often blurred. Computer software has to be 9loaded9 into the computer:s storage (such as

a hard drive memory or R!). ;nce the software is loaded the computer is able to

e%ecute the software. Computers operate by e%ecuting the computer program. ,his

involves passing instructions from the application software through the system software

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to the hardware which ultimately receives the instruction as machine code. "ach

instruction causes the computer to carry out an operation moving data carrying out a

computation or altering the control flow of instructions.

1." Soft!are #n$ineerin$

*oftware engineering is the study and an application of engineering to the design

development and maintenance of software.

,ypical formal definitions of software engineering are

• Research design develop and test operating systemslevel software compilers

and networ& distribution software for medical industrial military

communications aerospace business scientific and general computing

applications.

• ,he systematic application of scientific and technological &nowledge methods

and e%perience to the design implementation testing and documentation of

software.

software engineer is a licensed professional engineer who is schooled and s&illed in the

application of engineering discipline to the creation of software. software engineer is

often confused with a programmer but the two are vastly different disciplines. /hile a

programmer creates the codes that ma&e a program run a software engineer creates the

designs the programmer implements. #y law no person may use the title <engineer= (of

any type) unless the person holds a professional engineering license from a state licensing

board and are in good standing. software engineer is also held accountable to a specific

code of ethics.

1.% Structural &ei$n

*tructural design is the methodical investigation of the stability strength and rigidity of

structures. ,he basic ob0ective in structural analysis and design is to produce a structure

capable of resisting all applied loads without failure during its intended life. ,he primary

purpose of a structure is to transmit or support loads. If the structure is improperly

designed or fabricated or if the actual applied loads e%ceed the design specifications the

device will probably fail to perform its intended function with possible serious

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conse$uences. wellengineered structure greatly minimi-es the possibility of costly

failures

1.' Structural dei$n proce

structural design pro0ect may be divided into three phases i.e. planning design and

construction.

(lannin$) ,his phase involves consideration of the various re$uirements and factors

affecting the general layout and dimensions of the structure and results in the choice of

one or perhaps several alternative types of structure which offer the best general solution.

,he primary consideration is the function of the structure. *econdary considerations such

as aesthetics sociology law economics and the environment may also be ta&en into

account. In addition there are structural and constructional re$uirements and limitations

which may affect the type of structure to be designed.

&ei$n) ,his phase involves a detailed consideration of the alternative solutions defined

in the planning phase and results in the determination of the most suitable proportions

dimensions and details of the structural elements and connections for constructing each

alternative structural arrangement being considered.

Contruction) ,his phase involves mobili-ation of personnel> procurement of materials

and e$uipment including their transportation to the site and actual onsite erection.

uring this phase some redesign may be re$uired if unforeseen difficulties occur such as

unavailability of specified materials or foundation problems.

1.* #n$ineerin$ &ei$n (roce

,he engineering design process is a series of steps that engineers follow to come up with

a solution to a problem. !any times the solution involves designing a product (li&e a

machine or computer code) that meets certain criteria and?or accomplishes a certain tas&.

efine the criteria and constraints of a design problem with sufficient precision to

ensure a successful solution ta&ing into account relevant scientific principles and

potential impacts on people and the natural environment that may limit possible

solutions.

"valuate competing design solutions using a systematic process to determine how

well they meet the criteria and constraints of the problem.

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naly-e data from tests to determine similarities and differences among several

design solutions to identify the best characteristics of each that can be combined

into a new solution to better meet the criteria for success.

evelop a model to generate data for iterative testing and modification of a

proposed ob0ect tool or process such that an optimal design can be achieved.

"ngineering design process illustrated briefly in flow chart below

"ngineers do not always follow the engineering design process steps in order one after

another. It is very common to design something test it find a problem and then go bac&

to an earlier step to ma&e a modification or change to your design. ,his way of wor&ing is

called iteration.

1.+ ,eaon for developin$ thi Soft!are

4

aed on reult and data

mae dei$n chan$e/

prototype/ tet a$ain and

revie! ne! data

&evelop and (rototype

raintorm/ #valuate and

Solution eet Solution eet ,euirement

(artiall or ot at ll

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#eam column footing stair are the important elements of the whole building. "ngineers

should have to be careful and sincere to give an economic design within minimum time.

,his software will serve following purpose>

1. It will not only give accurate result but also save time and money.

. esign can be completed $uic&ly hence saving time it will increase the efficiency

of an engineer.

2. It will reduce the error due to arithmetic mista&es some error of mathematic

number and minimi-e the amount of manually handled data.

6. @arious types of building elements and mist of the cases the engineers perform

the design from their e%perience which is not accurate and not economical. ,his

software will reduce the labor and time and will ensure economical design.

1.15 ,eaon for uin$ 6iual Studio 251" and C Sharp

CA (C *harp) is an elegant simple typesafe ob0ectoriented language that allows

enterprise programmers to build a breadth of applications. It is a user friendly language.

CA is better than CBB because

• It has a huge standard library with so much useful stuff that:s wellimplemented

and easy to use.

• It allows for both managed and native code bloc&s.

• It allows you to treat classmethods: signatures as free functions (i.e. ignoring the

statically typed this pointer argument) and hence create more dynamic and fle%ible

relationships between classes.

• ssembly versioning easily remedy problems.

!icrosoft @isual *tudio is an integrated development environment (I") from !icrosoft.

It is used to develop computer programs for !icrosoft /indows as well as web sites

web applications and web services. @isual *tudio uses !icrosoft software development

platforms such as /indows 7I /indows 'orms /indows 7resentation 'oundation

/indows *tore and !icrosoft *ilverlight. It can produce both native code and managed

code. It has easy code navigation fast builds and $uic& deployment. @isual *tudio

increases productivity and ma&es it easy to do wor& alone or as part of a larger team.

D

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@isual CA is an implementation of the CA language by !icrosoft. @isual *tudio supports

@isual CA with a fullfeatured code editor compiler pro0ect templates designers code

wi-ards a powerful and easytouse debugger and other tools. ,he .N", 'ramewor&

class library provides access to many operating system services and other useful well

designed classes that speed up the development cycle significantly.

E

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Chapter-2

,einforced Concrete Structure

2.1 General

Concrete is one of the most popular materials for buildings because it has high

compressive strength fle%ibility in its form and it is widely available. ,he history of

concrete usage dates bac& for over a thousand years. Contemporary cement concrete has

been used since the early nineteenth century with the development of 7ortland cement.

espite the high compressive strength concrete has limited tensile strength only about

ten percent of its compressive strength and -ero strength after crac&s develop. In the late

nineteenth century reinforcing materials such as iron or steel rods began to be used to

increase the tensile strength of concrete. ,oday steel bars are used as common reinforcing

material. +sually steel bars have over 133 times the tensile strength of concrete> but the

cost is higher than concrete. ,herefore it is most economical that concrete resists

compression and steel provides tensile strength. lso it is essential that concrete and steel

deform together and deformed reinforcing bars are being used to increase the capacity to

resist bond stresses.

dvantages of reinforced concrete can be summari-ed as follows (Fassoun 1GG8).

1. It has a relatively high compressive strength.

. It has better resistance to fire than steel or wood

2. It has a long service life with low maintenance cost

6. In some types of structures such as dams piers and footing it is the most

economical structural material.

4. It can be cast to ta&e any shape re$uired ma&ing it widely used in precaststructural components.

lso disadvantages of reinforced concrete can be summari-ed as follows

1. It has a low tensile strength (-ero strength after crac&s develop).

. It needs mi%ing casting and curing all of which affect the final strength of

concrete.

2. ,he cost of the forms used to cast concrete is relatively high. ,he cost of form

material and artisanry may e$ual the cost of concrete placed in the forms.

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6. It has a lower compressive strength than steel (about 1?13 depending on material)

which re$uires large sections in columns of multistory buildings.

4. Crac&s develop in concrete due to shrin&age and the application of live loads.

2.2 Safety

structure must be safe against collapse> strength of the structure must be ade$uate for

all loads that might act on it. If we could build buildings as designed and if the loads and

their internal effects can be predicted accurately we do not have to worry about safety.

#ut there are uncertainties in

• ctual loads>

• 'orces?loads might be distributed in a manner different from what we assumed>• ,he assumptions in analysis might not be e%actly correct>

• ctual behavior might be different from that assumed etc.

'inally we would li&e to have the structure safe against brittle failure (gradual failure

with ample warning permitting remedial measures is preferable to a sudden or brittle

failure).

2.3 uildin$ Code ,euirement for Structural Concrete

#uildings must be designed and constructed according to the provisions of a building

code which is a legal document containing re$uirements related to such things as

structural safety fire safety plumbing ventilation and accessibility to the physically

disabled. building code has the force of law and is administered by a governmental

entity such as a city a county or for some large metropolitan areas a consolidated

government. #uilding codes do not give design procedures but specify the design

re$uirements and constraints that must be satisfied. ;f particular importance to the

structural engineer is the prescription of minimum live loads for buildings. /hile the

engineer is encouraged to investigate the actual loading conditions and attempt to

determine realistic values the structure must be able to support these specified minimum

loads. !any countries have their own structural design codes codes of practice or

technical documents which perform a similar function.It is necessary for a designer to

become familiar with local re$uirements or recommendations in regard to correct

practice. In this chapter some e%amples are given occasionally in a simplified form in

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order to demonstrate procedures. ,hey should not be assumed to apply to all areas or

situations. Fowever the +niform #uilding Code (+#C) and other model codes are

adapted by 0urisdictions such as Cities or *tates as governing codes. !aterial and

methods are tested by private or public organi-ations. ,hey develop share and

disseminate their result and &nowledge for adoption by 0urisdictions. ,he merican

Concrete Institute (CI) is leading the development of concrete technology. ,he CI has

published many references and 0ournals. #uilding Code Re$uirement for *tructural

Concrete (CI 218 Code) is a widely recogni-ed reinforced concrete design and

construction guide. lthough the CI Code does not have official power of enforcement

it is generally adapted as authori-ed code by 0urisdictions not only in +nited *tates but

also many countries. ,he CI218 Code provides the design and construction guide of

reinforced concrete. CI has been providing new codes depending on the change of

design methods and strength re$uirement.

2.4 Safety (roviion of the CI Code

oad factors are applied to the loads and a member is selected that will have enough

strength to resist the factored loads. In addition the theoretical strength of the member is

reduced by the application of a resistance factor. ,he criterion that must be satisfied in the

selection of a member is

'actored *trength H 'actored oad

In this e%pression the factored load is actually the sum of all wor&ing loads to be resisted

by the member each multiplied by its own load factor. 'or e%ample dead loads will have

load factors that are different from those for live loads. ,he factored strength is the

theoretical strength multiplied by a strength reduction factor. "$uation (1.2) can therefore be written as

Nominal *trength *trength Reduction 'actor H oad oad 'actors

*ince the factored load is a failure load greater than the actual wor&ing loads the load

factors are usually greater than unity. ;n the other hand the factored strength is a

reduced usable strength and the resistance factor is usually less than unity. ,he factored

loads are the loads that bring the structure or member to its limit.

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2." &ei$n ethod of ,einforced Concrete Structure

,wo ma0or calculating methods of reinforced concrete have been used from early 1G33Js

to current. ,he first method is called /or&ing *tress esign (/*) and the second is

called +ltimate *trength esign (+*). /or&ing *tress esign was used as the principal

method from early 1G33Js until the early 1GD3Js. *ince +ltimate *trength esign method

was officially recogni-ed and permitted from CI 2184D the main design method of

CI 218 Code has gradually changed from /* to +* method. ,he program of this

thesis is based on CI 21834 Code /hich published in 334.

2.".1 Chan$e of &ei$n ethod accordin$ to CI 31* Code (7C 1GGG).

CI 2184D +* was first introduced (1G4D)

CI 218D2 /* and +* were treated on e$ual basis.

CI 218E1 #ased entirely on strength !ethod (+*) /* was called lternate esign

!ethod (!).

CI 218EE ! relegated to ppendi% # CI 2188G ! bac& to ppendi%

CI 218G4 ! still in ppendi% +nified esign 7rovision was introduced in

ppendi% #

CI 2183 ! was deleted from ppendi% (CI 33).

2.".2 0he 7orin$ Stre &ei$n 87S&9

,raditionally elastic behavior was used as basis for the design method of 1D reinforced

concrete structures. ,his method is &nown as /or&ing *tress esign (/*) and also

called the lternate esign !ethod or the "lastic esign !ethod or llowable stress

design. ,his design concept is based on the elastic theory that assumes a straightline

stress distribution along the depth of the concrete section. ,o analy-e and design

reinforced concrete members the actual load under wor&ing conditions also called

service load condition is used and allowable stresses are decided depending on the safety

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factor. 'or e%ample allowable compressive bending stress is calculated as 3.64fJ c. If the

actual stresses do not e%ceed the allowable stresses the structures are considered to be

ade$uate for strength. ,he /* method is easier to e%plain and use than other method

but this method is being replaced by the +ltimate *trength esign method. CI 218 Code

treats the /* method 0ust in a small part.

,he wor&ing stress method may be e%pressed by the following

f K allowable stresses (f allowable) (1)

where f L an elastically computed stress such as by using the fle%ure formula f L !c?I

for beam.

f allow L limiting stress prescribed by a building code as a percentage of the compressive

strength f cM for concrete or of the yield stress f y for the steel reinforcing bars.

2.".3 0he :ltimate Stren$th &ei$n 8:S&9

,he +ltimate *trength esign method also called *trength esign !ethod (*!) is

based on the ultimate strength when the design member would fail. *ince 1GE1 the CI

Code has been totally a strength code with <strength= meaning ultimate. *elect concrete

dimensions and reinforcements so that the member strength are ade$uate to resist forces

resulting from certain hypothetical overload stages significantly above loads e%pected

actually to occur in service. ,he design concept is &nown as <strength design.= #ased on

strength design the nominal strength of a member must be calculated on the basis of

inelastic behavior of material. In other words both reinforcing steel and concrete behave

in elastically at ultimate strength condition.

,he strength design method may be e%pressed by the following

*trength provide H *trength re$uired to carry factored loads

where the <strength provided= such as moment strength is computed in accordance with

rules and assumptions of behavior prescribed by a building code and the <strength

re$uired= is that obtained by performing a structural analysis using the factored loads.

,he design procedure is roughly as follows

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!ultiply the wor&ing loads by the load factor to obtain the failure loads.

etermine the cross sectional properties needed to resist failure under these loads. (

member with these properties is said to have sufficient strength and would be at the verge

of failure when sub0ected to the factored loads.)

7roportion your members that have these properties.

#asic ssumptions for Concrete in +ltimate *trength esign method (CI)

l. *ections perpendicular to the a%is of bending that arc plane before bending remains

plane after bending.

. perfect bond e%ists between the reinforcement and the concrete such that the strain in

the reinforcement is e$ual to the strain in the concrete at the same level.

2. ,he strains in both the concrete and reinforcement are assumed to be directly

proportional to the distance from the neutral a%is (CI 13..).

6. Concrete is assumed to fail when the compressive strain reaches 3.332 (CI 13..2).

4. ,he tensile strength of concrete is neglected (CI 13..4).

D. ,he stresses in the concrete and reinforcement can be computed from the strains using

stressstrain curves for concrete and steel respectively.

E. ,he compressive stressstrain relationship for concrete may be assumed to be

rectangular trape-oidal parabolic or any other shape that results in prediction of strength

in substantial agreement with the results of comprehensive tests (CI 13..D). CI 13..E

outlines the use of a rectangular compressive stress distribution which is &nown as the

/hitney rectangular stress bloc&.

8. Reinforcing steel will yield when strain is e$ual to "y and stress after yield is always f y.

2.% ;oad

oads that act on structures can be divided into three general categories

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2.%.1 &ead ;oad) ead loads are those that are constant in magnitude and fi%ed in

location throughout the lifetime of the structure such as floor fill finish floor and

plastered ceiling for buildings and wearing surface sidewal&s and curbing for bridges.

2.%.2 ;ive ;oad) ive loads are those that are either fully or partially in place or not

present at all may also change in location> the minimum live loads for which the floors

and roof of a building should be designed are usually specified in building code that

governs at the site of construction

2.%.3 #nvironmental ;oad) "nvironmental oads consist of wind earth$ua&e and

snow loads. *uch as wind earth$ua&e and snow loads.

,he load factors are 1.E for live load and 1.6 for dead load. ;ther factors are given in

,able

0able 2-1) <actored load combination for determinin$ reuired tren$th :

Condition <actored load or load effect :

#asic + L 1.6 B 1.E

/inds

+ L 3.E4(1.6 B 1.E B 1.E/)

+ L 3.G B 1.2/

+ L 1.6 B 1.E

"arth$ua&e

+ L 3.E4(1.6 B 1.E B 1.8E")

+ L 3.G B 1.62"

+ L 1.6 B 1.E

"arth pressure

+ L 1.6 B 1.E B 1.EF

+ L 3.G B 1.EF

+ L 1.6 B 1.E

*ettlement creep shrin&age or temperature

change effects

+ L 3.E4(1.6 B 1.6, B 1.E)

+ L 1.6( B ,)

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2.' ,euired Stren$th

,he re$uired strength + is e%pressed in terms of factored loads or related internal

moments and forces. 'actored loads are the loads specified in the general building code

multiplied by appropriate factors. ,he factor assigned is influenced by the degree of

accuracy to which the load effect can be determined and the variation which might be

e%pected in the load during the lifetime of the structure. ead loads are assigned a lower

load factored than live load because they can be determined more accurately. oad factors

also account for variability in the structural analysis used to compute moments and

shears. ,he code gives load factors for specific combinations of loads. In assigning

factors to combinations of loading some consideration is given to the probability of

simultaneous occurrence. /hile most of the usual combinations of loadings are included

the designer should not assume that all cases are covered. @arious load combinations must

be considered to determine the most critical design condition. ,his is particularly true

when strength is dependent on more than one load effect such as strength for combined

fle%ure and a%ial load or shear strength in members with a%ial load. *ince the CI 218

#uilding Code is a national code it has to conform to the International #uilding Code

I#C31 and in turn be consistent with the *C"E *tandard on !inimum esign oads

for #uildings and ;ther structures. ,hese two standards contain the same probabilistic

values for the e%pected safety resistance factors OiRn where O is a strength reduction

factor depending on the type of stress being considered in the design such as fle%ure

shear or compression etc.

'actored oad Combinations for etermining Re$uired *trength + in CI Code

+ L 1.6( B ') (1)

+ L 1.( B ' B ,) B 1.D ( B F) B 3.4(r or * or R) ()

+ L 1. B 1.D (r or * or R) B (1.3 or 3.8/) (2)

+ L 1. B 1.D/ B 1.3 B 3.4(r or * or R) (6)

+ L 1. B 1.3" B 1.3 B 3.* (4)

+ L 3.G B 1.D/ B 1.DF (D)

+L 3.G B 1.3" B 1.DF (E)

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/here

L ead oad

L ive oad

" L"arth$ua&e oad

/L /ind oad

,L *elf*training force such as Creep *hrin&age 5 ,emperature "ffect

FLoad due to the weight 5 lateral pressure of soil and water in soil

r L Roof oad

RL Rain oad

*L *now oad

'L ateral fluid pressure oad

ue Regard is to be given to sign in determining + for combinations of loadings as one

type of loading may produce effects of opposite sense to that produced by another type.

,he load combinations with 3.G are specifically included for the case where a higher

dead load reduces the effects of other loads. ,he loading case may also be critical for

tension controlled column sections. In such a case a reduction in a%ial load and an

increase in moment may result in critical load combination.

"%cept for

,he load factor on in "$uation (2) to (4) shall be permitted to be reduced to 3.4 e%cept

for garages areas occupied as places of public assembly and all areas where the live load

is greater than 133 lb?ft.

/here wind load / has not been reduced by a directionality factor it shall be permitted

to use 1.2/ in place of 1.D/ in "$uations (6) and (D)

/here earth$ua&e load " is based on servicelevel seismic forces 1.6" shall be used in

place of 1.3" in "$uations (4) and (E).

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,he load factor on F shall be e$ual to -ero in "$uation (D) and (E) if the structural

action due to F counteracts that due to / or ". /here lateral earth pressure provides

resistance to structural actions from other forces. It shall not be included in F but shall be

included in the design resistance.

2.* &ei$n Stren$th

,he strength of a particular structural unit calculated using the current established

procedures is termed <nominal strength.= 'or e%ample in the case of a beam the resisting

moment capacity of the section calculated using the e$uations of e$uilibrium and

properties of concrete and steel is called the <nominal moment capacity= !n of the

section.

,he purpose of the strength reduction factor f are (!acPregor 1GED> and /inter 1GEG)

,o allow for understrength members due to variations in material strengths and

dimensions

,o permit for inaccuracies in the design provisions

,o reflect the degree of ductility and re$uired probability of the member under the load

effects being considered

,o reflect the importance of the member in the structure.

*trength Reduction 'actors ' of the CI Code

,ension controlled sections QQQQQQQQQQQQQ..3.G3

Compression controlled sections

i. !embers with spiral reinforcement QQQQQQ...3.E4

ii. ;ther members QQQQQQQQQQQQQ...3.D4

*hear and torsion QQQQQQQQQQQQQQQQQ..3.E4

#earing on Concrete QQQQQQQQQQQQQQQQ.3.D4

7lain Concrete QQQQQQQQQQQQQQQQQQ...3.44

2.+ Concrete Cover for ,einforcement

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Concrete cover for reinforcement is re$uired to protect the rebar against corrosion and to

provide resistance against fire. ,he thic&ness of cover depends on environmental

conditions and type of structural member. ,he minimum thic&ness of reinforcement cover

is indicated in the drawings or shall be obtained from the relevant code of practice.

#elow are the specifications for reinforcement cover for different structural members in

different conditions.

a) t each end of reinforcing bar net less than 1 inch or 4 mm or less than twice the

diameter of the bar.

b) 'or a longitudinal reinforcing bar in a column not less than 8?4 inch or 63 mm not less

than the diameter of such bar. In case of columns of minimum dimension of 8 in or 3 cm

under whose reinforcing bards do no not e%ceed in or 1 mm a cover of 1 inch or 4

mm to be used.

c) 'or longitudinal reinforcing bars in a beam not less than D?4 inch or 23 mm or less

than the diameter of the bar.

d) 'or tensile compressive shear or other reinforcements in a slab or wall not less than

2?4 inch or 14 mm not less that the diameter of such bar.

e) 'or any other reinforcement not less than 2?4 inch or 14 mm not less than the diameter

of such bar.

f) 'or footings and other principal structural members in which the concrete is deposited

directly against the ground cover to the bottom reinforcement shall be 2 inch or E4 mm.

If concrete is poured on a layer of lean concrete the bottom cover maybe reduced to

inch or 43 mm.

g) 'or concrete surfaces e%posed to the weather or the ground after removal of forms

such as retaining walls grade beams footing sides and top etc. not less than inch or 43

mm.

h) Increased cover thic&ness shall be provided as indicated on the drawings for surfaces

e%posed to the action of harmful chemicals (or e%posed to earth contaminated by such

chemicals) acid al&ali saline atmosphere sulphorone smo&e etc.

i) 'or li$uid retaining structures the minimum cover to all steel shall be 8?4 inch or 63

mm or the diameter of the main bar whichever is greater. In the presence of sea water and

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oils and waters of a corrosive character the covers shall be increased by ?4 inch or 13

mm.

0) 7rotection to reinforcement in case of concrete e%posed to harmful surroundings may

also be given by providing a dense impermeable concrete with approved protective

coatings. In such a case the e%tra cover mentioned in (b) 5 (i) above may be reduced.

&) ,he correct cover shall be maintained by cement mortar cubes (bloc&s) or other

approved means. Reinforcements for footings grade beams and slabs on a subgrade shall

be supported on recast concrete bloc&s as approved by "IC. ,he use of pebbles or stones

shall not be permitted.

l) ,he minimum clear distance between reinforcing bars shall by in accordance with I*

64D S 333 or as shown in drawing.

2.15 Selection of ar and ar Spacin$

Common reinforcing bar si-es range from No. 2 to No. 11 (No. 13 to No. 2D) the bar

number corresponding closely to the number of eighthinches (millimeters) of bar

diameter. ,he two larger si-es No. 16 (No. 62) T1.E4 inch. (62 mm) diameterU and No. 18

(No. 4E) T.4 inch. (4E mm) diameterU are used mainly in columns.

It is often desirable to mi% bar si-es to meet steel area re$uirements more closely. Ingeneral mi%ed bars should be of comparable diameter for practical as well as theoretical

reasons and generally should be arranged symmetrically about the vertical centerline.

!any designers limit the variation in diameter of bars in a single layer to two bar si-es

using say No. 13 and No. 8 (No. 2 and No. 4) bars together but not Nos. 11 and D

(Nos. 2D and 1G). ,here is some practical advantage to minimi-ing the number of

different bar si-es used for a given structure.

Normally it is necessary to maintain a certain minimum distance between ad0acent bars to

ensure proper placement of concrete around them. ir poc&ets below the steel are to be

avoided and full surface contact between the bars and the concrete is desirable to

optimi-e bond strength. CI Code E.D specifies that the minimum clear distance between

ad0acent bars not be less than the nominal diameter of the bars or 1 inch. ('or columns

these re$uirements are increased to 1.4 bar diameters and 1.4 inch.) /here beam

reinforcement is placed in two or more layers the clear distance between layers must not

1G

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be less than 1 inch and the bars in the upper layer should be placed directly above those

in the bottom layer.

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Chapter-3

,evie! of Structural &ei$n on the CI Code

3.1 eam

3.1.1 Introduction

#eams are structural elements carrying transverse e%ternal loads that cause bending

moment shear forces and in some cases torsion across their length. Concrete is strong in

compression and very wea& in tension. *teel reinforcement is used to ta&e up tensile

stresses in reinforced concrete beams. /hen the bending moment acts on the beam

bending strain is produced. ,he resisting moment is developed by internal stresses. +nder positive moment compressive strains are produced in the top of beam and tensile strains

in the bottom. Concrete is a poor material for tensile strength and it is not suitable for

fle%ure member by itself. ,he tension side of the beam would fail before compression

side failure when beam is sub0ected a bending moment without the reinforcement. 'or

this reason steel reinforcement is placed on the tension side. ,he steel reinforcement

resists all tensile bending stress because tensile strength of concrete is -ero when crac&s

develop. In the +ltimate *trength esign (+*) a rectangular stress bloc& is assumed

('ig. 21).

'ig 21 Reinforced rectangular beam (mbrose 1GGE)

s shown 'ig. 21 the dimensions of the compression force is the product f beam width

depth and length of compressive stress bloc&. ,he design of beam is initiated by the

calculation of moment strengths controlled by concrete and steel.

3.1.2 0ype of eam

'ig. 2 shows the most common shapes of concrete beams single reinforced rectangular

beams doubly reinforced rectangular beams ,shape beams spandrel beams and 0oists.In castSinplace construction the single reinforced rectangular beam is uncommon. ,he

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,shape and shape beams are typical types of beam because the beams are built

monolithically with the slab. /hen slab and beams are poured together the slab on the

beam serves as the flange of a ,beam and the supporting beam below slab is the stem or

web. 'or positive applied bending moment the bottom of section produces the tension

and the slab acts as compression flange. #ut negative bending on a rectangular beam putsthe stem in compression and the flange is ineffective in tension. Voists consist of spaced

ribs and a top flange.

'ig. 2 Common shapes of concrete beam (*piegel 1GG8)

3.1.3 ,einforced Concrete eam &ei$n (arameter

a. ,einforcement ,atio)

,he amount of steel reinforcement in concrete members should be limited. ;ver

reinforcing (the placement of too much reinforcement) will not allow the steel to yield

before the concrete crushes and there is a sudden failure. ,he reinforcement ratio in

concrete beam design is the following fraction

= s

,he reinforcement ratio W must be less than a value determined with a concrete strain of

3.332 and tensile strain of 3.336 (minimum). /hen the strain in the reinforcement is

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3.334 or greater the section is tension controlled. ('or smaller strains the resistance factor

reduces to 3.D4 because the stress is less than the yield stress in the steel.)

b. a=imum ,einforcement)

#ased on the limiting strain of 3.334 in the steel x(or c) = 0.375d so

X L Y1 (3.2E4d) to find sma%

,he values of Y1 are presented in the following ,able 6.1

c. inimum ,einforcement)

!inimum reinforcement is provided even if the concrete can resist the tension in order to

control crac&ing.

!inimum re$uired reinforcement

A s=c ΄

bwd #ut not less than

s= w

where

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f y is the yield strength in psi

bw is the width of the web of a concrete ,#eam cross section

d L the effective depth from the top of a reinforced concrete beam to the centroid of the

tensile steel.

d. Cover for ,einforcement)

Cover of concrete over?under the reinforcement must be provided to protect the steel from

corrosion. 'or indoor e%posure 1.4 inch is typical for beams and columns 3.E4 inch is

typical for slabs and for concrete cast against soil 2 inch minimum is re$uired.

e. ar Spacin$)

!inimum bar spacing are specified to allow proper consolidation of concrete around the

reinforcement. ,he minimum spacing is the ma%imum of 1 in a bar diameter or 1.22

times the ma%imum aggregate si-e.

f. #ffective !idth beff )

In case of ,#eams or Pamma#eams the effective slab can be calculated as follows

i. 'or interior ,sections beff is the smallest of

?6 bw B 1Dt or center to center of beams

ii. 'or e%terior ,sections beff is the smallest of

bw B ?1 bw B Dt or bw B (clear distance to ne%t beam)

/hen the web is in tension the minimum reinforcement re$uired is the same as for

rectangular sections with the web width (bw) in place of b.

/hen the flange is in tension (negative bending) the minimum reinforcement re$uired is

the greater value of

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A s=c ΄

bwd or

As=c ΄

b d

where

f y is the yield strength in psi

bw is the width of the web of a concrete ,#eam cross section

beff is the effective flange width

3.1.4 &ei$n (rocedure

,ectan$ular eam

1. ssume the depth of beam using the CI Code reference minimum thic&ness

unless consideration the deflection.

. ssume beam width (ratio of with and depth is about 1).

2. Compute selfweight of beam and design load.

6. Compute factored load

4. Compute design moment (!u).

D. Compute ma%imum possible nominal moment for singly reinforced beam(Z!n).

E. ecide reinforcement type by Comparing the design moment (!u) and the

ma%imum possible moment for singly reinforced beam (Z!n). If Z!n is less

than !u the beam is designed as a doubly reinforced beam else the beam can

be designed with tension steel only.

8. etermine the moment capacity of the singly reinforced section.(concrete

steel couple)

G. Compute the re$uired steel area for the singly reinforced section.

13. 'ind necessary residual moment subtracting the total design moment and the

moment capacity of singly reinforced section.

0-hape eam

1. Compute the design moment (!u).

. ssume the effective depth.

2. ecide the effective flange width (b) based on CI criteria.

6. Compute the practical moment strength (Z!n) assuming the total effective

flange is supporting the compression.

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4. If the practical moment strength (Z!n) is bigger than the design moment

(!u) the beam will be calculated as a rectangular ,beam with the effective

flange width b. If the practical moment strength (Z!n) is smaller than the

design moment (!u) the beam will behave as a true ,shape beam.

D. 'ind the appro%imate lever arm distance for the internal couple.

E. Compute the appro%imate re$uired steel area.

8. esign the reinforcement. G. Chec& the beam width.

G. Compute the actual effective depth and analy-e the beam.

3.2 Column

3.2.1 Introduction

Columns support primarily a%ial load but usually also some bending moments. ,he

combination of a%ial load and bending moment defines the characteristic of column and

calculation method. column sub0ected to large a%ial force and minor moment is design

mainly for a%ial load and the moment has little effect. column sub0ected to significant

bending moment is designed for the combined effect. ,he CI Code assumes a minimal

bending moment in its design procedure although the column is sub0ected to compression

force only. Compression force may cause lateral bursting because of the lowtension

stress resistance. ,o resist shear ties or spirals are used as column reinforcement to

confine vertical bars. ,he comple%ity and many variables ma&e hand calculations tedious

which ma&es the computeraided design very useful.

3.2.2 0ype of Column

Reinforced concrete columns are categori-ed into five main types> rectangular tied

column rectangular spiral column round tied column round spiral column and columnsof other geometry (Fe%agonal shaped ,*haped etc.).

'ig. 22 shows the rectangular tied and round spiral concrete column. ,ied columns have

hori-ontal ties to enclose and hold in place longitudinal bars. ,ies are commonly No. 2 or

No.6 steel bars. ,ie spacing should be calculated with CI Code.

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'ig. 22 Column types

,he columns are also categori-ed into three types by the applied load types. ,he column

with small eccentricity the column with large eccentricity (also called eccentric column)

and bia%ial bending column. 'ig 26 shows the different column types depending on

applied load.

'ig. 26 ,he column types depending on applied load.

"ccentricity is usually defined by location

• Interior columns usually have

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• "%terior columns usually have large eccentricity

• Corner column usually has bia%ial eccentricity.

'ig. 24 "ccentric loaded conditions (*piegel 1GG8)

#ut eccentricity is not always decided by location of columns. "ven interior columns can

be sub0ected by bia%ial bending moment under some load conditions 'ig. 24 shows some

e%amples of eccentric load conditions.

3.2.3 CI Code Safety (roviion for Column

'or columns as for all members designed according to the CI Code ade$uate safety

margins are established by applying load factors to the service loads and strength

reduction factors to the nominal strengths. ,hus for columns Z7n H7u and Z!n [H !u are

the basic safety criteria. 'or most members sub0ect to a%ial compression or compression

plus fle%ure (compression controlled members the CI Code provides basic reduction

factors

ZL 3.D4 for tied columns

Z L 3.E4 for spirally reinforced columns

,he spread between these two values reflects the added safety furnished by the greater

toughness of spirally reinforced columns.

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,here are various reasons why the Z values for columns are lower than those for fle%ure

or shear (3.G3 and 3.E4 respectively). ;ne is that the strength of under reinforced fle%ural

members is not much affected by variations in concrete strength since it depends

primarily on the yield strength of the steel while the strength of a%ially loaded members

depends strongly on the concrete compressive strength. #ecause the cylinder strength of

concrete under site conditions is less closely controlled than the yield strength of mill

produced steel a larger occasional strength deficiency must be allowed for. ,his is

particularly true for columns in which concrete being placed from the top down in a

long narrow form is more sub0ect to segregation than in hori-ontally cast beams.

!oreover electrical and other conduits are fre$uently located in building columns> this

reduces their effective cross sections often to an e%tent un&nown to the designer even

though this is poor practice and restricted by the CI Code. 'inally the conse$uences of a

column failure say in a lower story would be more catastrophic than those of a single

beam failure in the same building.

'or high eccentricities as the eccentricity increases from e b to infinity (pure bending) the

CI Code recogni-es that the member behaves progressively more li&e a fle%ural member

and less li&e a column. s described in Chapter 2 this is ac&nowledged in CI Code

G.2. by providing a linear transition in Z from values of 3.D4 and 3.E4 to 3.G3 as the net

tensile strain in the e%treme tensile steel t increases from f y?"s (which may be ta&en

as 3.33 for Prade D3 reinforcement) to 3.334.

t the other e%treme for columns with very small or -ero calculated eccentricities the

CI Code recogni-es that accidental construction misalignments and other unforeseen

factors may produce actual eccentricities in e%cess of these small design values. lso the

concrete strength under high sustained a%ial loads may be somewhat smaller than the

shortterm cylinder strength. ,herefore regardless of the magnitude of the calculated

eccentricity CI Code 13.2.Dlimits the ma%imum design strength to 3.83cfV7 3 for tied

columns (with ZL 3.D4) and to 3.84Z73 for spirally reinforced columns (with ZL 3.E4)

where P0 is the nominal strength of the a%ially loaded column with -ero eccentricity.

,he effects of the safety provisions of the CI Code are shown in 'ig.2.and represents

the actual carrying capacity as nearly as can be predicted. ,he smooth curve shown

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partially dashed then solid then dashed represents the basic design strength obtained by

ma%imum design load stipulated in the CI Code for small eccentricities i.e. large a%ial

loads as 0ust discussed. t the other end for large eccentricities i.e. small a%ial loads

the

'ig.2D CI safety provisions superimposed on column strength interaction diagram.

CI Code permits a linear transition of\ from 3.D4 or 3.E4 applicable for t K f y?"s (or

3.33 for Prade D3 reinforcement) to 3.G3 at t L 3.334. #y definition t L f y?"s at

the balanced condition. ,he effect of the transition in Z is shown at the lower right end of

the design strength curve.

3.2.4 ehavior of =ially ;oaded Column

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/hen an a%ial load is applied to a reinforced concrete short column the concrete can be

considered to behave elastically up to a low stress of about f c] If the load on the

column is increased to reach its ultimate strength the concrete will reach the ma%imum

strength and the steel will reach its yield strength f y ,he nominal load capacity of the

column can be written as follows

73L 3.84f c]n B stf y

/here n and stL the net concrete and total steel compressive areas respectively.

n L g S st

g L Pross concrete area

,wo different types of failure occur in columns depending on whether ties or spirals are

used. 'or a tied column the concrete fails by crushing and shearing outward the

longitudinal steel bars fail by buc&ling outward between ties and the column failure

occurs suddenly. !uch li&e the failure of a concrete cylinder.

'ig. 2E #ehavior of ,ied and *piral Column

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spiral column undergoes a mar&ed yielding followed by considerable deformation

before complete failure. ,he concrete in the outer shell fails and spalls off. ,he concrete

inside the spiral is confined and provides little strength before the initiation of column

failure hoop tension develops in the spiral and for a closely spaced spiral^ the steel

may yield sudden failure is not e%pected 'igure 2 shows typical load deformation

curves for tied and spiral columns. +p to point a both columns behave similarly. t point

a the longitudinal steel bars of the column yield and the spiral column shell spalls off

after the factored load is reached a tied column fails suddenly (curve b) whereas a spiral

column deforms appreciably before failure (curve c).

3.2." ia=ial endin$

,he design of eccentrically loaded columns using the strain compatibility method of

analysis described re$uires that a trial column be selected. ,he trial column is then

investigated to determine if it is ade$uate to carry any combination of 7 u and !u that may

act on it should the structure be overloaded if 7u and !u from the analysis of the

structure when plotted on a strength interaction diagram such as 'ig. 2E fall within the

region bounded by the curve labeled 9CI design strength.9 'urthermore economical

design re$uires that the controlling combination of 7u and !u be close to the limit curve.

If these conditions are not met a new column must be selected for trial. ,his !ethod

permit rectangular or s$uare columns to be designed if bending is present about only one

of the principal a%es. ,here are situations by no means e%ceptional in which a%ial

compression is accompanied by simultaneous bending about both principal a%es of the

section. *uch is the case for instance in corner columns of buildings where beams and

girders frame into the columns in the directions of both walls and transfer their end

moments into the columns in two perpendicular planes. *imilar loading may occur at

interior columns particularly if the column layout is irregular.

,he situation with respect to strength of bia%ially loaded columns is shown in 'ig. 28.

et and _ denote the directions of the principal a%es of the cross section. In 'ig. 28(a)

the section is shown sub0ect to bending about the _ a%is only with load eccentricity e%

measured in the direction .,he corresponding strength interaction curve is shown as

case (a) in the threedimensional s&etch in 'ig. 28(d) and is drawn in the plane defined

by the a%es 7n and !ny . *uch a curve can be established by the usual methods for unia%ial

,he situation with respect to strength of bia%ially loaded columns is shown in 'ig. 28.

2

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et and _ denote the directions of the principal a%es of the cross section. In 'ig. 28(a)

the section is shown sub0ect to bending about the _ a%is only with load eccentricity e%

measured in the direction .,he corresponding strength interaction curve is shown as

case (a) in the threedimensional s&etch in 'ig. 28(d) and is drawn in the plane defined

by the a%es 7n and !ny . *uch a curve can be established by the usual methods for unia%ial

bending. *imilarly 'ig.28(b) shows bending about the a%is only with eccentricity ey

measured in the _ direction. ,he corresponding interaction curve is shown as case (b) in

the plane of 7n and !n% in 'ig. 28(d). 'or case (c) which combines and _ a%is

bending the orientation of the resultant eccentricity is defined by the angle ` T2U

λ=tan− x

=tan− ny

22

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'ig 28 Interaction diagram for compression plus bia%ial bending

a. unia%ial bending about _ a%is>

b. unia%ial bending about a%is>

c. bia%ial bending about diagonal a%is>

d. Interaction surface.

#ending for this case is about an a%is defined by the angle Ɵ with respect to the a%is.

,he angle ` in 'ig. 28(c) establishes a plane in 'ig. 28(d) passing through the vertical

7n a%is and ma&ing an angle ` with the !n% a%is as shown. In that plane column strength

is defined by the interaction curve labeled case (c). 'or other values of similar curves

are obtained to define a failure surface for a%ial load plus bia%ial bending such as shown

in 'ig. 28(d). ,he surface is e%actly analogous to the interaction curve for a%ial load plusunia%ial bending. ny combination of 7u !u% and !uy falling inside the surface can be

applied safely but any point falling outside the surface would represent failure. Note that

the failure surface can be described either by a set of curves defined by radial planes

passing through the 7n a%is such as shown by case (c) or by a set of curves defined by

hori-ontal plane intersections each for a constant 7n defining load contours.

,he nominal ultimate strength of a section under bia%ial bending and compression is a

function of three variables 7n!n% and !ny which may also be e%pressed as 7n acting at

eccentricities eyL!n%?7n and e%L !ny?7n /ith respect to the and _ a%is.

Constructing such an interaction surface for a given column would appear to be an

obvious e%tension of unia%ial bending analysis. In 'ig. 28(c) for a selected value of Ɵ

successive choices of neutral a%is distance c could be ta&en. 'or each using strain

compatibility and stressstrain relations to establish bar forces and the concrete

compressive resultant then using the e$uilibrium e$uations to find 7n !n% and !ny onecan determine a single point on the interaction surface. Repetitive calculations easily

done by computer then establish sufficient points to define the surface. ,he triangular or

trape-oidal compression -one such as shown in 'ig. 28(c) is a complication and in

general the strain in each reinforcing bar will be different but these features can be

incorporated.

,he main difficulty however is that the neutral a%is will not in general be perpendicular

to the resultant eccentricity drawn from the column center to the load 7n 'or each

26

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successive choice of neutral a%is there are uni$ue values of 7n !n% and !ny and only for

special cases will the ratio of !n?!n% be such that the eccentricity is perpendicular to the

neutral a%is chosen for the calculation. ,he result is that for successive choices of c for

any given Ɵ the value of ` in 'ig.28(c) and d will vary. 7oints on the failure surface

established in this way will wander up the failure surface for increasing 7n not

representing a plane intersection as shown for case (c) in 'ig. 28(d).

In practice the factored load 7u and the factored moments ! u% and !uy to be resisted are

&nown from the frame analysis of the structure. ,herefore the actual value of

`Larctan(!uy?!u%) is established and one needs only the curve of case (c) 'ig. 8.1Dd to

test the ade$uacy of the trial column. lternatively simple appro%imate methods #resler

load contour method and Reciprocal method are widely used.

3.2.".1 reler load contour method

,he load contour method is based on representing the failure surface of 'ig. 28(d) by a

family of curves corresponding to constant values of 7n. ,he general form of these curves

can be appro%imated by a nondimensional interaction e$uation T2U

M ny 0

¿ =1

M nx

M nx0¿α 1+¿

/here

!n%L7ney>

!n%3L!n%> when !ny L 3.

!nyL7ne%>

!ny3L!ny. /hen !n% L 3.

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,he e%ponentJs X1 and X are e%ponents depending on column dimensions amount and

distribution of steel reinforcement stressstrain characteristics of steel and concrete

amount of concrete cover and si-e of lateral ties or spiral.

3.2.".2 reler reciprocal method

simple appro%imate design method developed by #resler has been satisfactorily

verified by comparison with results of e%tensive tests and accurate calculations It is noted

that the column interaction surface in 'ig. 2G(d) can alternatively be plotted as a

function of the a%ial load 7n and eccentricities e% L!ny?7n and ey L!n%?7n as is shown in

'ig. 2G(a). ,he surface *1 of 'ig. 2G(a) can be transformed into an e$uivalent failure

surface * as shown in 'ig.2G(b) where e% and ey are plotted against 1?7n rather than 7n.,hus e% L ey L 3 corresponds to the inverse of the capacity of the column if it were

concentrically loaded 73 and this is plotted as point C. 'or ey L 3 and any given value of

e% there is a load 7ny3 (corresponding to moment !ny3) that would result in failure. ,he

reciprocal of this load is plotted as point . *imilarly for e% L 3 and any given value of ev

there is a certain load 7n%3 (corresponding to moment !n%3) that would cause failure the

reciprocal of which is point #. ,he values of 7n%3 and 7ny3 are easily established for

&nown eccentricities of loading applied to a given column using the methods already

established for unia%ial bending or using design charts for unia%ial bending.

2D

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'ig 2G Interaction surfaces for the reciprocal load method.

n obli$ue plane *] is defined by the three points # and C. ,his plane is used as an

appro%imation of the actual failure surface *.Note that for any point on the surface *

(for any given combination of e% and e) there is a corresponding plane *. ,hus the

appro%imation of the true failure surface * involves an infinite number of planes *]

determined by particular pairs of values of e% and ey i.e. by particular points # and C.

,he vertical ordinate 1?7ne%act to the true failure surface will always be conservatively

estimated by the distace 1?7nappro% to the obli$ue plane #C (e%tended) because of the

concave upward eggshell shape of the true failure surface. In other words 1?7 nappro% is

always greater than 1?7ne%act .which means that 7nappro% is always less than 7ne%act.

#resler:s reciprocal load e$uation T2U derives from the geometry of the appro%imating

plane. It can be shown that

= + −

2E

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/here

7n L appro%imate value of nominal load in bia%ial bending with eccentricities e % and ey

7nyo L nominal load when only eccentricity e% is present (ey L 3)

7n%o L nominal load when only eccentricity ey is present (e% L 3)

73 L nominal load for concentrically loaded column.

,est result indicate that above e$uation may be inappropriate when small values of a%ial

load are involvef such as when 7n?73 is in the range of 3.3D or less.'or such cases the

member should be desined for fle%ure only.


• Short Column !ith mall eccentricitie

1. "stablish the material strength and steel area.

. Compute the factored a%ial load.

2. Compute the re$uired gross column area.

6. "stablish the column dimensions.

4. Compute the load on the concrete area.

D. Compute the load to be carried by the steel.E. Compute the re$uired steel area.

8. esign the lateral reinforcing (ties or spiral).

G. *&etch the design.

Short Column !ith lar$e eccentricitie

1. "stablish the material strength and steel area.

. Compute the factored a%ial load ( Pu) and moment ( Mu).

2. etermine the eccentricity (e).

6. "stimate the re$uired column si-e based on the a%ial load and 13

eccentricity.4. Compute the re$uired gross column area.

D. "stablish the column dimensions.

E. Compute the ratio of eccentricity to column dimension perpendicular to the

bending a%is.

8. Compute the ratio of a factored a%ial load to gross column area.

G. Compute the ratio of distance between centroid of outer rows of bars to

thic&ness of the cross section in the direction of bending.

13. 'ind the re$uired steel area using the CI chart.

11. esign the lateral reinforcing (ties or spiral).

1. *&etch the design.

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3.3 <ootin$

3.3.1 Introduction

,he foundation of a building is the part of a structure that transmits the load to ground to

support the superstructure and it is usually the last element of a building to pass the load

into soil roc& or piles. ,he primary purpose of the footing is to spread the loads into

supporting materials so the footing has to be designed not to be e%ceeded the load

capacity of the soil or foundation bed. ,he footing compresses the soil and causes

settlement. ,he amount of settlement depends on many factors. "%cessive and differential

settlement can damage structural and nonstructural elements. ,herefore it is important to

avoid or reduce differential settlement. ,o reduce differential settlement it is necessary totransmit load of the structure uniformly. +sually footings support vertical loads that

should be applied concentrically for avoid une$ual settlement. lso the depth of footings

is an important factor to decide the capacity of footings. 'ootings must be deep enough to

reach the re$uired soil capacity.

3.3.2 0ype of <ootin$

,he most common types of footing are strip footings under walls and single footings

under columns. Common footings can be categori-ed as follow

1. Individual column footin$ 8<i$ 3-%a9) ,his footing is also called isolated or

single footing. It can be s$uare rectangular or circular of uniform thic&ness

stepped or sloped top. ,his is one of the most economical types of footing. ,he

most common type of individual column footing is s$uare of rectangular with

uniform thic&ness.

. 7all footin$ 8<i$3-%b9) /all footings support structural or nonstructural walls.

,his footing has limited width and a continuous length under the wall.

2. Combined footin$ 8<i$3-%e9) ,hey usually support two or three columns not in a

row and may be either rectangular or trape-oidal in shape depending on column. If

a strap 0oins two isolated footings the footing is called a cantilever footing.

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'ig 213 'ooting types (*piegel 1GG8)

6. at foundation 8<i$3-%f9) !ats are large continuous footings usually placed

under the entire building area to support all columns and walls. !ats are used

when the soilbearing capacity is low column loads are heavy single footings

cannot be used piles are not used or differential settlement must be reduced

through the entire footing system.

4. (ile footin$ 8<i$3-%$9) 7ile footings are thic& pads used to tie a group of piles

together and to support and transmit column loads to the piles.

3.3.3 &ei$n Conideration

'ooting must be designed to carry the column loads and transmit them to the soil safety

while satisfying code limitation. ,he design procedure must ta&e the following strength

re$uirements into consideration

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,he area of the footing based on the allowable bearing soil capacity

,woway shear or punching shear

;neway shear

#ending moment and steel reinforcement re$uired

owel re$uirements

evelopment length of bars


Individual column footin$

1. Compute the factored loads.

. ssume the total footing thic&ness.

2. Compute the footing selfweight the weight of earth on top of the footing.

6. Compute the effective allowable soil pressure for superimposed service loads.

4. Compute re$uired footing area.D. Compute the factored soil pressure from superimposed loads.

E. ssume the effective depth for the footing.

8. Chec& the punching shear and beam shear.

G. Compute the design moment at the critical section.

13. Compute the re$uired steel area.

11. Chec& the CI Code minimum reinforcement re$uirement.

1. Chec& the development length.

12. Chec& the concrete bearing strength at the base of the column

3.4 Stair

3.4.1 Introduction

*taircase is an important component of a building providing access to different floors and

roof of the building. It consists of a flight of steps (stairs) and one or more intermediate

landing slabs between the floor levels. ifferent types of staircases can be made by

arranging stairs and landing slabs. *taircase thus is a structure enclosing a stair.

3.4.2 0ype of Staircae

,here are different types of *tairs which depend mainly on the type and function of the

building and on the architectural re$uirements. *ome of the common types of staircases

based on geometrical configurations

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'ig 211 ,ypes of *taircases

(a) *ingle flight staircase ('ig 2E a)

(b) ,wo flight staircase ('ig 2E b)

(c) ;penwell staircase ('ig 2E c)

(d) *piral staircase ('ig 2E d)

(e) Felical staircase ('ig 2E e)

rchitectural considerations involving aesthetics structural feasibility and functional

re$uirements are the ma0or aspects to select a particular type of the staircase. ;ther

influencing parameters of the selection are lighting ventilation comfort accessibility

space etc.

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'ig 21 ,ransversely *upported *tairs

'or purpose of design stairs are classified into two types> transversely and longitudinally

supported.

. ,ransversely supported (transverse to the direction of movement)

,ransversely supported stairs include

a. *imply supported steps supported by two walls or beams or a combination of

both.

b. *teps cantilevering from a wall or a beam.

c. *tairs cantilevering from a central spine beam.

#. ongitudinally supported (in the direction of movement),hese stairs span between supports at the top and bottom of a flight and

unsupported at the sides. ongitudinally supported stairs may be supported in any

of the following manners

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'ig 212 ongitudinally *upported *tairs

a. #eams or walls at the outside edges of the landings.

b. Internal beams at the ends of the flight in addition to beams or walls at the

outside edges of the landings.

c. andings which are supported by beams or walls running in the longitudinal

direction. d. combination of (a) or (b) and (c).

*tairs with $uarter landings associated with openwell stairs.

3.4.3 Component of Stair

,he definitions of some technical terms which are used in connection with design of

stairs are given.

a. 0read or Goin$) hori-ontal upper portion of a step.

b. ,ier) vertical portion of a step.

c. ,ie) vertical distance between two consecutive treads.

d. <li$ht) a series of steps provided between two landings.

e. ;andin$) a hori-ontal slab provided between two flights.

f. 7ait) the least thic&ness of a stair slab.

g. 7inder) radiating or angular tapering steps. h. *offit the bottom surface of a stair

slab.

h. oin$) the intersection of the tread and the riser.

i. >eadroom) the vertical distance from a line connecting the nosings of all treads

and the soffit above.

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'ig. 216 *tairs main Components


esign procedure foe single flight *tair

1. 'irst calculate the loads.

. ,hen calculate ma%imum moment.

2. Chec& the depth. If o& then go to ne%t steps otherwise change the section.

6. Calculate reinforcement.4. Chec& for bond and development length.

D. Calculate reinforcement of first flight and spacing.

E. *&etch reinforcement details.

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Chapter 4

,einforced Concrete Structure &ei$ner 8,CS&9

4.1 General

RC* is a computer program for reinforced concrete structure design according to the

CI Code. It includes beam column stair and footing design. Its main purpose is to help

architecture students who do not have enough structural bac&ground but need a structural

calculation to design their building. *o this program is developed with easy to use

interface based on CI Code procedures. RC* provides step by step calculations and is

composed of separate modules for beam stair column and footing design. ,he step by

step design method is considered one of the best methods to help beginning users li&e

civil engineering students. 'or e%ample users do not need to input the all re$uired data at

once. ,he program as&s the minimum re$uired data and provides defaultinput data. ,he

user can use the default data or select other data.

,he modular RC* program structure also has the advantage that each module is

e%ecutable separately and the user can add other modules. RC* is programmed using

!icrosoft @isual *tudio 314. @isual *tudio is much easier to learn than other languages

and provides good graphic user interface (P+I). "ach module is composed of multiple

pages that have been organi-ed using !icrosoft ,abbed Control ialog Component. "ach

module is e%ecuted step by step along the tabs. ,abs are divided into frames for better

organi-ation of different category of input and output data.

RC* is a computer program for reinforced concrete structure design according to the

CI Code. It includes beam column stair and footing design. Its main purpose is to help

architecture students who do not have enough structural bac&ground but need a structural

calculation to design their building. *o this program is developed with easy to use

interface based on CI Code procedures. RC* provides step by step calculations and is

composed of separate modules for beam stair column and footing design. ,he step by

step design method is considered one of the best methods to help beginning users li&e

civil engineering students. 'or e%ample users do not need to input the all re$uired data at

6D

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once. ,he program as&s the minimum re$uired data and provides defaultinput data. ,he

user can use the default data or select other data.

,he modular RC* program structure also has the advantage that each module is

e%ecutable separately and the user can add other modules. RC* is programmed using

!icrosoft @isual *tudio 314. @isual *tudio is much easier to learn than other languages

and provides good graphic user interface (P+I). "ach module is composed of multiple

pages that have been organi-ed using !icrosoft ,abbed Control ialog Component. "ach

module is e%ecuted step by step along the tabs. ,abs are divided into frames for better

organi-ation of different category of input and output data.

4.2 eam odule

4.2.1 Introduction

RC* provides single and double reinforced beam design method in one module in both

/* and +* method.

4.2.2 ,ectan$ular eam &ei$n odule

,he beam design module has IN7+, R"*+, and R"IN';RC"!"N, ",I. ,he

IN7+, tab contain !aterial *trength !oment *hear and imension.

'ig. 6.1 #eam esign !odule

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4.2.3 0 eam &ei$n odule

,he beam design module has IN7+, R"*+, and R"IN';RC"!"N, ",I. ,he

IN7+, tab contain !aterial *trength !oment *hear and imension.

'ig. 6. , #eam esign !odule

4.3 Column odule

4.3.1 Introduction

Column is classified into two types spiral column and tied Column. ,he ,ied Column can

be classified into two types +nia%ial and #ia%ial #ending. ,his program provides all

three types of column design. ,he design of column carrying small eccentricity is

calculated by simple method computed by the CI method for a%ial load with small

eccentricity. If a%ial load is applied with eccentricity the column is sun0ected to moment

and more bending strength.

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4.3.2 Column &ei$n odule

,he column design module has contains three tabs tied column for unia%ial bia%ial

bending and spiral column. ,he tied portion designs for bia%ial bending unia%ial

bending a%ial load. ,he spiral design portion for a%ial load as it is wea& in bending. "ach

design tab contains IN7+, R"*+, and R"IN';RC"!"N, ",I*.

'ig 6.2 Column design module.

4.4 <ootin$ odule

4.4.1 Introduction

,his program provides design module foe individual column footing. ,he thic&ness of the

footing is calculated from twoway and one way shear chec& and the thic&ness is chec&ed

with the bending moment at the face of the column.

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4.4.2 <ootin$ &ei$n module

Individual column footing module has IN7+, ;+,7+, R"IN';RC"!"N, ",I*

tabs. ,he IN7+, tab contains load material column si-e and soil condition based on this

data the program calculates footing si-e and thic&ness to resist shear.

'ig 6.6> 'ooting esign !odule

4." Stair module

4.".1 Introduction

In stair design module some material property and loading data has to input and it gives

the re$uired section for design reinforcement.

4.".2 Stair &ei$n odule

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*tair module has IN7+, ;+,7+, and R"IN';RC"!"N, IPR! tabs. ,he

IN7+, tab re$uires dimension material strength oad. #ased on the input data this

program calculates possible section for reinforcement

'ig. 6.4 *tair esign !odule

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Chaptre-"

Concluion and ,ecommendation

".1 Concluion

,his simplified reinforced concrete structure design program for civil engineering

students based on the merican Concrete Institute Code (CI 218) is e%pected to help

engineering students to design sound concrete structures. ,he ultimate goal of this

program is to assist students in the reinforced concrete structures design and guide them

to design structurally safe buildings. CI Code is the most common code of Reinforce

Concrete structure design but it is difficult to use for beginner users. ,his program will

help engineers in determining the economical si-e and reinforcement re$uirement of a

structural members such as #eam column 'ooting and *tairs within short times per

merican Concrete Institute Code (CI 218). ,he main purpose of this program is to

provide as much basic information to users. RC* does not restrict user to use 0ust one

answer but provides many possibility of structural member design for a set of building

condition. ,hus each calculation was divided into several steps provide typical image for

better understanding popup window is provided to help to get economical section.

".2 ,ecommendation

RC* has four design module #eam (Rectangular ,beam) Column (+nia%ial #ia%ialand spiral) Individual column footing and *tair. ,here has not been enough time to

actually test this program with studentJs actual design and to get feedbac& and add assist

buttons. *everal improvements can be made to this software such as

1. dd ,hree imensional (2) graphical output. !ost students are familiar with

2computer graphics such as utodes& utoC. If this software uses the 2d

graphic output it will be really helpful to students to understand the structure and

connection between structural members.

. dding more design modules would give high degree acceptance such as *lab

(;neway solid slab ,woway slab) *hear wall 7ile foundation !at foundation

wall footing design etc.

2. ifferent types of unit conversions can be added.

6. 7rinting the result with reinforcement details can be added.

4. ,he software can be improve from suitable logic in future.

D. ,he design should be analy-ed repeatedly and thoroughly.

I am hoping that another student will improve this software and develop it to ma&e it an

easier and more useful program.

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,#<#,#C#S

T1U CI Committee 218 #uilding Code Re$uirements for *tructural Concrete and

Commentary CI 21834 and CI 218R34 merican Concrete Indtitution 334.

TU CI Committee 214 etails and etailing of Concrete Reinforcement CI 214GG

(Revised 34) merican Concrete Institute 334.

T2U Nilson rthur F. arwin avid and olan Charles /. esign of Concrete

*tructures 16th "dition !cPrawFill Companies Inc. New _or& 33G.

T6U *implified esign of Reinforced Concrete2rd "dition by Fenry 7ar&er.

T4U 7hil ! 'ergution <Reinforced Concrete 'undamentals= 'ourth edition Vohn /iley 5

*ons Inc. 1G82.

TDU Vac& C. !cCormac 5 Russell F. #rown <esign of Reinforced Concrete= Ninth

"dition Vohn /iley 5 *ons Inc. 316.

TEU /inter+r$uhrat ; Rour&eNilson <esign of Concrete *tructures= *eventh "dition

!cPrawFill Companies Inc. New _or&.

T8U Computer ided esign of @arious *tructural !embers +sing @isual *tudio 313 by

!. ,RI+ I*! Roll No 3G331 epartment of Civil "ngineering R+",316.

TGU Reinforced Concrete *tructure esign ssistant ,ool for #eginners developed by

angyu Choi for the faculty of the *chool of rchitecture +niversity of *outhern

California 33

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$w 6 dou$le.7arse'txtWW.Text(;

-! 6 dou$le.7arse'txtFT.Text(;

a$ 6 '3.0=0 < '$n @ E( < '$n @ E(( @ =;

!c0 6 0 < !c/;

!y 6 0 < !y/;

a= 6 -!;

s0 6 'M<0/( @ '.? < !y < 'd .> < a=((;

a> 6 's0 < !y( @ '.E> < !c0 < $(;

@@ Flenge rea and Moment

s! 6 '.E> < '!c0 @ !y( < '$ $w( < -!(;

M! 6 .? < s! < !y < 'd .> < -!(;

@@We$Rs ein!orcement rea

Mw 6 M < 0/ M!;

i! 'a> -!( @@ T %eam 5nsure

#


a 6 3;

!or 'int i 6 0; i K6 =; iBB(

#

swNiO 6 'Mw( @ '.? < !y < 'd 'a @ /(((;

a0NiO 6 'swNiO < !y( @ '.E> < !c0 < $w(;

a/ 6 a0NiO;

a3 6 a/ a;

i! 'a3 K6 ./>(

#

s 6 swNiO B s!;

DD

7/21/2019 CHap 1,2,3,4 & 5.docx


l$lesult.Text 6 Hein!orcement rea'sqin(6H B 's(.ToString'( B HInH B

H:um$er o! ein!orcement6H B Mat-.ound's @ a$(.ToString'(;






$rea2;

+

a 6 a/;

+

+

else i! 'a> K -!(

#

Message%ox.S-ow'HT-e %eam will act as a 5CT:GL %eamH(;


a 6 3;

!or 'int i 6 0; i K6 =; iBB(

#

swNiO 6 'Mw( @ '.? < !y < 'd 'a @ /(((;

a0NiO 6 'swNiO < !y( @ '.E> < !c0 < $(;

a/ 6 a0NiO;

a3 6 a/ a;

i! 'a3 K6 ./>(

#

l$lesult.Text6 Hein!orcement rea'sqin(6H B 'swNiO( B HInH B

H:um$er o! ein!orcement6H B Mat-.ound'swNiO @ a$(;

txts/.Text 6 Mat-.ound'swNiO @ a$(.ToString'( B HJH B $n.ToString'(;

DE

7/21/2019 CHap 1,2,3,4 & 5.docx


txtd/.Text 6 d.ToString'( B HinH;

txt$0.Text 6 $w.ToString'( B HinH;

$rea2;

+

a 6 a/;

+

+

+

+

+

,ied Column

+* !ethod

using System;


D8

7/21/2019 CHap 1,2,3,4 & 5.docx



using System.Data;


using System.Linq;

using System.Text;



#

pu$lic partial class Tied"Column"niaxial & Form

#

pu$lic Tied"Column"niaxial'(

#


+

dou$le !c0, dl, ll, !y, $, -, d, pg, pu, g,M, -0, a, c, c0, !s, st, s0,Mo, 7$, M$, Md, $n, a$;

pri4ate 4oid $tnSu$mit"Clic2'o$1ect sender, 54entrgs e(

#


!y 6 dou$le.7arse'txt8S.Text(;

dl 6 dou$le.7arse'txtDL.Text(;

ll 6 dou$le.7arse'txtLL.Text(;


$ 6 dou$le.7arse'txtC9.Text(;

- 6 dou$le.7arse'txtCS.Text(;

pg 6 dou$le.7arse'txtCS.Text(;


a$ 6 '3.0=0 < '$n @ E( < '$n @ E((;

DG

7/21/2019 CHap 1,2,3,4 & 5.docx


pu 6 0./ < dl B 0. < ll;

g 6 pu @ '.E> < .A < '.E> < !c0 B .0 < pg < !y((;

-0 6 g @ $;

i! '- -0(

#

@@5ecti4e dept- o! Column d

d 6 - /;

a 6 pu @ '.E> < !c0 < $(;

c 6 a @ .E>;

c0 6 .3 @ '.3 B !y @ /?(;

@@%alanced !ailure condition !s6!y ,s06st@/

st 6 'pg < g( @ 0;

!s 6 !y;

s0 6 st @ /;

7$ 6 '.E> < !c0 < a < $( 's0 < !s( B 's0 < !y(;

M$ 6 7$ < .> < '- a( B s0 < !s < '.> < - /.>( B s0 < 'd - @ /(;

@@ o4erturning moment

Mo 6 .= < s0 < !y < d;

@@ Design Moment

Md 6 '''pu < 'M$ Mo(( @ 7$( B Mo(<0/;

i!'Md K M(

#

l$lesult.Text 6 HSteel area 'sqin(6H B st.ToString'( B HInH B H:um$er o! $ar&H BMat-.ound'st @ a$(.ToString'(;

+

else

#

Message%ox.S-ow'H7lease C-ange T-e S5CT)Q:H(;

E3

7/21/2019 CHap 1,2,3,4 & 5.docx


+

+

else

#

Message%ox.S-ow'Hplease C-ange t-e section o! t-e columnH(;

+

+

+

+

,ied Column #ia%ial

+* !ethod

using System;



using System.Data;


using System.Linq;

using System.Text;



E1

7/21/2019 CHap 1,2,3,4 & 5.docx


#

pu$lic partial class Tied"Column"%iaxial & Form

#

pu$lic Tied"Column"%iaxial'(

#


+

dou$le 7, Mx, My, $,!c0,!y, -, ex, ey, m, 7o,px,py, $n, a$, s,st, Fa, F$, n, c0, c/, )x, )y,Sutx, Suty, 7n, pg;

pri4ate 4oid $tnSu$mit"Clic2'o$1ect sender, 54entrgs e(

#



7 6 dou$le.7arse'txtTL.Text(;

Mx 6 dou$le.7arse'txtMx.Text(;

My 6 dou$le.7arse'txtMy.Text(;

$ 6 dou$le.7arse'txtCW.Text(;

- 6 dou$le.7arse'txtC9.Text(;


pg 6 dou$le.7arse'txtpg.Text(;

a$ 6 '3.0=0 < '$n @ E( < '$n @ E((;

@@ eciprocal Met-od

ex 6 'Mx < 0/ @ 7(;

ey 6 'My < 0/ @ 7(;

m 6 !y @ '.E> < !c0(;

7o 6 '.3= < '0 B .0 < pg < m( < !c0 < $ < -(@0;

@@ Condition !a@FaB!$@F$60

Fa 6 .3= < !c0 < '0 B .0 < pg < m(;

E

7/21/2019 CHap 1,2,3,4 & 5.docx


F$ 6 .=> < !c0;

s 6 .0 < pg < $ < -;

n 6 Mat-.ound''/? < 0( @ '>A < Mat-.Sqrt'!c0(((;

)x 6 $ < - < - < - @ 0/ B / < s < '/ < n 0( < '- @ / /.>( < '- @ / /.>(;

)y6 - < $ < $ < $ @ 0/ B / < s < '/ < n 0( < '$ @ / /.>( < '$ @ / /.>(;

c0 6 - @ /;

c/ 6 $ @ /;

Sutx 6 )x @ c0;

Suty 6 )y @ c/;

px 6 ''0 Mx < 0/ @ Sutx( < $ < - < Fa( @ 0;

py 6 ''0 My < 0/ @ Suty( < $ < - < Fa( @ 0;

@@ %resler 5quation

7n 6 '0 @ '0 @ px B 0 @ py 0 @ 7o((<0;

i! '7n7(

#

st 6 .0 < pg < $ < -;

l$lesult.Text 6 Hein!orcement area 'sqin(6H B st.ToString'( B HInH B HDesignLoad'2ip(6H B 7n.ToString'( B HInH B

H:um$er o! %ar&H B Mat-.ound'st @ a$(.ToString'(;


txts.Text6 Mat-.ound'st @ a$(.ToString'(BHJHB$n.ToString'(;

txt$.Text 6 $.ToString'( B Hinc-H;

txt-.Text 6 -.ToString'( B Hinc-H;

+

else

#

Message%ox.S-ow'HDesign is:QT QP, 7lease c-ange t-e sectionH(;

+

E2

7/21/2019 CHap 1,2,3,4 & 5.docx


+

+

+

*piral Column

+* !ethod

using System;



using System.Data;


using System.Linq;

using System.Text;



#

pu$lic partial class Spiral"Column"Design"SD & Form

#

pu$lic Spiral"Column"Design"SD'(

#


+

dou$le !c, !y, Dl, Ll, 7g, g, D, D0, g0, 7c, 7s, s, $n$, a$, dc, 7s0, 7s/, s, 7u, c;

E6

7/21/2019 CHap 1,2,3,4 & 5.docx



#

!c 6 dou$le.7arse'txtCS.Text(;


Dl 6 dou$le.7arse'txtDL.Text(;

Ll 6 dou$le.7arse'txtLL.Text(;

7g 6 dou$le.7arse'txtS.Text(;

$n$ 6 dou$le.7arse'txt%:.Text(;

a$ 6 '.AE>= < '$n$ @ E( < '$n$ @ E((;

7u 6 '0./ < Dl B 0. < Ll(;

g 6 '7u( @ '.A < .E> < '.E> < !c < '0 .0 < 7g( B .0 < 7g < !y((;

D 6 Mat-.Sqrt''= < g( @ 3.0=0(;

D0 6 Mat-.ound'D(;

g0 6 '3.0=0 < D0 < D0( @ =;

@@ Load carried $y comrete 7c

7c 6 .A < .E> < .E> < g0 < '0 7g < .0( < !c;

@@ load carried $y steel 7s

7s 6 7u 7c;

@@ Steel rea s

s 6 7s @ '.E> < .A < !y(;

@@ assuming co4er 0.>RR

dc 6 D0 / < 0.>;

c 6 '3.0=0 < dc < dc( @ =;

7s0 6 .=> < !c < ''g0 @ c( 0( @ !y;

s 6 '= < .00( @ '7s0 < dc(;

7s/ 6 ''= < a$( @ 'dc < s((;

E4

7/21/2019 CHap 1,2,3,4 & 5.docx


l$lesult.Text 6 H Diameter o! column 'inc-(&6H B D0.ToString'( B HInH B Hein!orcementrea 'Sqin(,s 6H B s.ToString'( B

HInH B Hno o! $ar6H B Mat-.ound's @ a$(.ToString'(BHInHBHse J3 spiral steelinc@c6HB Mat-.ound's(.ToString'(;

+

+

+

'ooting esign

+* !ethod

using System;



using System.Data;


using System.Linq;

using System.Text;



ED

7/21/2019 CHap 1,2,3,4 & 5.docx


#

pu$lic partial class Design"Square"Footing & Form

#

pu$lic Design"Square"Footing'(

#


+

dou$le !c0, !y, W, D, dl, ll,M, a, q, qu, $, c,a3,$3,c3,smin,s0,x3,x=, d, $0, x0,p,s,

x/, , 0, s, -, L, L0,n, $n, a$, m, u, c;


#



W 6 dou$le.7arse'txtSW.Text(;

D 6 dou$le.7arse'txtDF.Text(;

dl 6 dou$le.7arse'txtDL.Text(;

ll 6 dou$le.7arse'txtLL.Text(;


$0 6 dou$le.7arse'txtCW.Text(;

q 6 dou$le.7arse'txtS7.Text(;

a$ 6 '3.0=0 < '$n @ E( < '$n @ E(( @ =;

0 6 'dl B ll( @ 'q W < .0 < D(;

L0 6 Mat-.Sqrt'0(;

@@lengt-U Widt-

L 6 Mat-.Ceiling'L0</(@/;

6 L < L;

qu 6 ''0./ < dl B 0. < ll(( @ ; @@ 2s!

EE

7/21/2019 CHap 1,2,3,4 & 5.docx


@@punc-ing S-ear

@@For equili$rium u6c

@@ u6<qu''$0Bd(@0/(<'$0<d(@0/((<qu

@@c6=<.?<Mat-.Sqrt'!c0(<'=<'$0Bd(<d(

@@ Critical Dept- d calculation

m 6 '0 < .A> < Mat-.Sqrt'!c0( < 0==( @ qu;

a 6 m B 0;

$ 6 $0 < m B / < $0;

c 6 '0== < B $0 < $0(;

p 6 $ < $ = < a < c;

@@ quadratic equation is a second order o! polynomial equation in a single 4aria$le

@@ x 6 N $ B@ sqrt'$V/ =ac( O @ /a

i! 'p (

#

x0 6 '$ B System.Mat-.Sqrt'p(( @ '/ < a(;

x/ 6 '$ System.Mat-.Sqrt'p(( @ '/ < a(;

i! 'x0 K UU x/(

#

d 6 x0 <'0(;

+

else i! 'x/ K UU x0(

#

d 6 x/ <'0(;

+

+

@@ %eam S-ear C-ec2

u 6 'L @ / $0 @ /= d @ 0/( < L < qu;

c 6 / < .A> < Mat-.Sqrt'!c0( < d < L < 0/;

E8

7/21/2019 CHap 1,2,3,4 & 5.docx


i! 'c u(

#

@@ Moment Calculation

M 6 .> < 'L < qu < '.> < L $0 @ /=((; @@ 2!t

@@ein!orcement rea calculation

n 6 !y @ '.E> < !c0 < L < 0/(;

a3 6 .> < n;

$3 6 d;

c3 6 'M<0/( @ '.? < !y(;

s 6 $3 < $3 = < a3 < c3;

i! 's (

#

x3 6 '$3 B System.Mat-.Sqrt's(( @ '/ < a3(;

x= 6 '$3 System.Mat-.Sqrt's(( @ '/ < a3(;

i! 'x3 K x= UU x3 (

#

s0 6 x3;

+

else i! 'x= K x3 UU x= (

#

s0 6 x=;

+

+

smin 6 './ @ !y( < L < 0/ < d; @@ inc-

i! 'smin s0(

#

s 6 smin;

EG

7/21/2019 CHap 1,2,3,4 & 5.docx


+

else

#

s 6 s0;

+

@@ T-ic2ness o! t-e !ooting

- 6 d B 0.> < '$n @ E( B 3 B .>;

l$lesult.Text 6 HLengt- Q! Footing,L'!t(6H B L.ToString'( B HInH B HWidt- o! Footing6H BL.ToString'( B HInH B Hein!orcement rea'sqin(6H B 's(.ToString'( B HInH B

HT-ic2ness Q! Footing'in(6H B Mat-.ound'-(.ToString'( B HInH B H:o o! %ar6H B

Mat-.ound''s( @ a$(.ToString'(;


txtL.Text 6 L.ToString'(BHinH;

txtL0.Text 6 L.ToString'(BHinH;

txt-.Text 6 Mat-.ound'-(.ToString'(BHinH;

txts.Text 6 Mat-.ound''s( @ a$(.ToString'(B HJHB$n.ToString'(;

txts0.Text 6 Mat-.ound''s( @ a$(.ToString'( B HJH B $n.ToString'(;

+

else

#

Message%ox.S-ow'HS-ear C-ec2 is :ot QPH(;

+

+

+

+

83

7/21/2019 CHap 1,2,3,4 & 5.docx


*tair esign

/* !ethod

using System;



using System.Data;


using System.Linq;

using System.Text;


using System.Windows.Forms.Design;


#

pu$lic partial class Stair"Design"WSD & Form

#

pu$lic Stair"Design"WSD'(

#


+

dou$le !c0, !y, t, T, , nt, s, st, s, s0, 5, max, d, all, $n, w, ww, Mmax, LL, DL, n, 0,2, 1, $a, !c, !s, r,

w/, wt, wl, l0, r0, a, L, , de, d0, l/, r/, wr, d0, all0;

81

7/21/2019 CHap 1,2,3,4 & 5.docx



#



t 6 dou$le.7arse'txtWT.Text(;

T 6 dou$le.7arse'txtTW.Text(;

6 dou$le.7arse'txtW.Text(;

LL 6 dou$le.7arse'txtLL.Text(;

DL 6 dou$le.7arse'txtDL.Text(;


l/ 6 dou$le.7arse'txtLeL.Text(;

r/ 6 dou$le.7arse'txtL.Text(;

nt 6 dou$le.7arse'txt:T.Text(;

$a 6 .AE>= < '$n @ E( < '$n @ E(;

!c 6 .=> < !c0;

!s 6 .= < !y;

n 6 '/? @ '>A < 'Mat-.Sqrt'!c0((((;

r 6 '!s @ !c(;

2 6 n @ 'n B r(;

1 6 0 '2 @ 3(;

0 6 .> < !c < 1 < 2;

l0 6 '> @ 0/( B l/;

r0 6 '> @ 0/( B r/;

@@ total Lengt-

L 6 l0 B r0 B 'nt < T( @ 0/;

@@total ig-t

6 'nt < T( @ 0/;

@@ load calculation

8

7/21/2019 CHap 1,2,3,4 & 5.docx


ww 6 't @ 0/( < 0>;

@@load !or step portion

w 6 ww < 'Mat-.Sqrt'T < T B < (( @ T;

@@wt o! ange

w/ 6 .> < ' @ 0/( < 0>;

wt 6 w B w/ B LL B DL B 00./>;

@@wt on landing

wl 6 ww B 00./> B LL;

wr 6 00./> B LL;

@@Moment calculation

a 6 'wl < l0 < 'l0 @ /( B wr < r0 < 'r0 @ / B ' B l0(( B wt < < 'l0 B @ /(( @ L;

Mmax 6 a < L @ / wl < l0 < 'L @ / l0 @ /( wt < 'L @ / l0( < .> < 'L @ / l0(;

d0 6 Mat-.Sqrt'Mmax @ 0(;

de 6 t '3 @ =( < .><'$n @ E(;

i! 'de d0(

#

Message%ox.S-ow'HDept- C-ec2 is o2H(;

+

else

#

Message%ox.S-ow'HDept- C-ec2 is not o2H(;

+

@@ein!orcement calculation

s 6 'Mmax < 0/( @ '!s < 1 < de(;

s 6 Mat-.ound''$a < 0/( @ s(;

@@distri$ution ein!orcement

st 6 .0E < 0/ < t;

s0 6 Mat-.ound''.00 < 0/( @ st(;

82

7/21/2019 CHap 1,2,3,4 & 5.docx


5 6 '3.0=0 < $n < 0/( @ '$n @ E(;

@@S-ear C-ec2

max 6 a;

d 6 max @ '5 < 1 < de(;

all 6 3.= < Mat-.Sqrt'!c0( @ '$n @ E(;

i! 'all d(

#

Message%ox.S-ow'HS-ear c-ec2 is o2H(;

+

else

#

Message%ox.S-ow'HS-ear c-ec2 is not Q2H(;

+

@@ %ond c-ec2

d0 6 a @ '0/ < de(;

all0 6 00 < Mat-.Sqrt'!c0(;

i! 'all0 d0(

#

Message%ox.S-ow'H%ond c-ec2 is o2H(;

+

else

#

Message%ox.S-ow'H%ond c-ec2 is not o2H(;

+

picture%ox0.isi$le 6 true;


txtM.isi$le 6 true;

txtM/.isi$le 6 true;

86

7/21/2019 CHap 1,2,3,4 & 5.docx


txtD.isi$le 6 true;

txtD/.isi$le 6 true;

l$lesult.ext 6 HMain ein!orcement rea'Sqin(6H B s.ToString'( B HInH B

H:um$er o! rein!orcement 6H B Mat-.ound's@ $a(.ToString'( B HInH B HDistri$utionrein!orcement rea'Sqin(6H B st.ToString'( B

HInH B H:um$er o! rein!orcement 6H B Mat-.ound'st @ $a(.ToString'(;

txtM.Text 6 s.ToString'(;

txtM/.Text 6 s.ToString'(;

txtD.Text 6 st.ToString'(;

txtD/.Text 6 st.ToString'(;

+

+

+

chap 1,2,3,4 & 5.docx

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