load analysis and structural consideration

• Load and types.

• Structure after load analysis.

• Load transfer.

-Core and load analysis.

-Floorings and types.

-Basement and parking

CONTENT

• Load is the external forces acting on very small area

on a perpendicular point of a supporting structural

element.

LOAD

• GEOPHISICAL

SOURCES OF BUILDING LOADS:

• MAN MADE

TYPES OF LOAD:

DIFFERENT TYPES OF LOAD:

DEAD LOAD: (gravity/static load)

Dead load consists of self weight of structure (beam, column, slab & struts etc.) &

equipment permanently attached to structure such as furniture load, home

accessories etc.

LIVE LOAD:

Loads caused by contents of objects within or on a building are called occupancy loads. This

loads includes allowance for the weights of people, furniture, moveable partitions,

mechanical equipment etc.

CONSTRUCTION LOADS

• Structural members may be subjected to loads larger than designed loads during

erection of a building these loads called construction loads

• The weight of floor forms and newly placed slab, which in total may equal twice

the floor load.

TYPES AND EFFECTS OF TEMPERATURE LOAD :

TYPES OF COLUMN EXPOSURE

inside Flange at wall line Partial exposure Full exposure

TYPES AND EFFECTS OF TEMPERATURE-INDUCED MOVEMENT:

COLUMN BENDING:

DIFFERENTIAL MOVEMENT

BETWEEN INTERIOR AND

EXTERIOR COLUMNS.

column temperature may vary from -20 F to

120 F depending on the locality .

expansion

Cold air

contraction

Warm air

WIND LOAD: (dynamic/lateral load) The mean wind velocity is generally increases with height.

Wind is essentially the large scale horizontal movement of free air. It plays an

important role in design of tall structure because it exerts loads on building.

WIND DIRECTION:

The multidirectional displacement may be

less than It would have been if the same

airflow had encountered the building on

only one face.

WIND TURBULENCE:

Wind pressure:

The wind pressure originates from two

components previously defined : mean velocity

and gust velocity. since static mean velocities are

averaged over longer periods of time, the

resulting wind pressure are also average

pressure and exert a steady deflection on the

building.

SEISMIC LOAD: (dynamic/lateral load)

It is this wave motion that is known as earthquake., It is

apparent that a fault which has suffered from

earthquakes in the past is most likely subject to future

disturbances.

When earthquakes occur, a buildings undergoes

dynamic motion. This is because the building is

subjected to inertia forces that act in opposite direction

to the acceleration of earthquake excitations.

These inertia forces, called seismic loads

Earthquake is one of the destructive events in the world.

When earthquakes occur, a buildings undergoes dynamic motion.

Earthquake shaking is random

Ground shaking during earthquakes

Result of earthquake

Load Transfer :

Different shapes of buildings considered in the present study

Shape:

Circular Shape

Rectangular Shape

Square Shape

Triangular Shape

Lateral , horizontal

and

vertical load transfer

LOAD TRANSFER IN STRUCTURE

Bracing:

It is a device used as a supporting beam in a building that imparts rigidity

and steadies the structure. It is extremely stiff. It helps positioning, supporting,

strengthening or restraining the member of a structural frame.

The basic principles are as follows:

·Vertical K-bracing maybe used along the columns

· Horizontal portal bracing may be applied along the beams .

Braced Frame

• The effectiveness of the system, as characterized by a high ratio of

stiffness to material quantity, is recognized for multistory building in the

low to mid height range.

• Generally regarded as an exclusively steel system because the diagonal

are inevitably subjected to tension for or to the other directions of lateral

loading.

• Able to produce a laterally very stiff structure for a minimum of additional

material, makes it an economical structural form for any height of

buildings, up to the very tallest.Advantages:

- Girders only participate minimally in the lateral bracing action

- Floor framing design is independent of its level in the structure

- Can be repetitive up the height of the building with obvious economy in

design and fabrication.Disadvantages:

- Obstruct the internal planning and the locations

of the windows and doors; for this reason,

braced bent are usually incorporated internally

along wall and partition lines, especially around elevator,

stair, and service shaft.

- Diagonal connections are expensive to fabricate and erect

Type of High-Rise Structure

1. Braced Frame

2. Rigid Frame Structure

3. In filled Frame Structure

4. Flat Plate and Flat Slab Structure

5. Shear wall structure

6. Coupled wall structure

7. Wall-frame structure

8. Framed tube structure

9. The trussed tube

10. Tube in tube or Hull core structure

11. Bundled tube structure

12.Core and Outrigger system

13. Hybrid structure

Tubed mega frame • Vertical tube mega column

• No central core

• That’s why all the load of the building rest on its

perimeter

Load transfer in CCTV Tower China

Outrigger system

• central core with outriggers, connecting

the core to the outer columns.

• the central contains either braced frame of

shear wall.

North east asia trade tower

Infilled Frame Structure

• Infilled serve also as external walls or internal

partitions, the system is an economical way

of stiffening and strengthening the structure.

• Consists of reinforce or steel column and

girder frame with infills of brick work or

concrete block works

Vertical displacement in infill frame structure:

Shear wall

• Concrete wall

• Punches are limited because of torsional and flexural

rigidity

• In most cases lateral loads are carried by shear walls.

Shear wall

• Gravity load and lateral

load are ideally distributed.

• Also shear wall carries all

lateral loads.

Lateral load

Gravity load

What is steel shear wall?

Diagrid system

• Here diagrid acts as a rigid shell and

beam for support where rings are

also used.

• lateral loads are introduced

directly to the diagrid structure and

immediately transferred into the

triangulation system these loads are

then handled in a similar manner to

vertical

• Load paths are continuous and

uninterrupted.

• Vertical gravity loads follow the structure of

the tube from top to base along the

diagonal members of said tube.

• Each diagonal can be viewed as

continuous from top of tube to the bottom

of the tube – this is one option for a load to

follow to meet the ground

Rings

Flat plate and flat slab structure

• flat plate is a two-way reinforced concrete

framing system utilizing a slab of uniform

thickness, the simplest of structural shapes

• flat slab is a two-way reinforced structural

system that includes either drop panels or

column capitals at columns to resist heavier

loads and thus permit longer spans.

Tube in tube structure:

Bundle tube

• The inner and

outer tube jointly

resist the gravity

and lateral loads.

Bundle tube structure:

• This system easily

resist the wind pressure

and hold lateral loads.Tube in tube

Framed tube structure

• Gravity loads are distributed between the tubes and

interior columns or walls

• Lateral loading acts at the perimeter.

STEPS OF FLOORING

• BASE-lay base coat of 100mm

thick in the ratio of cement

concrete 1:8:16 ( 1 part of

cement,8 parts of fine sand &

16 parts of brick blast) or

1:4:8 on compaced earth under

the floor. The base is same for

all types of floors.

• FINISHING: then finishing of

the floor is carried on, for

different flooring materials. As

we will discuss here the

finishing of

terrazzo,brick,stone & cement

concrete floor

-Hard flooring

-Sub flooring

TYPES OF FLOORING

Hard flooringHard flooring (not to be confused with

( "hardwood") is a family of

flooring materials that includes concrete or

cement, ceramic tile,glass

tiles, and natural stone products.

Sub flooring

The floor under the flooring is called the subfloor,

which provides the support for the flooring.

Special purpose

subfloors like floating floors, raised floors or sprung

floors may be laid upon another

underlying subfloor provides the structural strength.

Subfloors that are below grade

(underground) or ground level floors in buildings

Basement and parking

Generally basements are common in tall buildings as carparks,

storage of servicesand underground shopping centres. The

Basement Parking space type refers to parking located below

grade within an occupied building.

The main purpose of constructing basements are:

(a) to provide additional space,

(b) as a form of buoyancy raft,

(c) in some cases, basements may be needed for

reducing net bearing pressure by the

removal of the soil.

(d) safe and efficient passage of automobiles as well as

visitors to and from their vehicles

Buoyancy raft

Function and attributes of basement

Additional Structural Requirements:

Below grade extension of the building structure to

accommodate basement parking is required. This

involves additional excavation, structural frame, floor

slabs above, sloped vehicle access ramps, and

basement perimeter walls and partitions separating

parking from other building enclosed areas. Typical

structural floor construction is 4000 PSI 6" concrete

slab with welded wire fabric designed for a live load of

80 LBS/SF, and with a ramp slope of no more than

5.5%.

Importancs of basement

CORE:

The core of a multistory building that integrates functions and

service needs for established occupants. Such areas are

normally composed of toilet facilities, elevator banks, janitors’

closet, utilities, mechanical facilities, smoke shafts and stair.

25% - 30% of the total circulation area.

Core also known as facade envelope is a spatial element

for load-bearing high-rise building system

• Vertical circulation

• Configuration

• Floor-plate design

• Function of Service Core

• Service core types & placement

• Service Core & Building Economy

• Elevator design & configuration

• Population density

• Traffic analysis

• Quality of ride

• Service-core layout & space

requirements

Core wall

There are two principles of core design arrangement .

the first is providing effective and conveninet vertical

transportation system. The second is creating intact ,

flexible and consistently high quality space that can be

occupied which can be adapted into the structural

system.

Shanghai tower design.

Shenzhen pingan financial center

INTERIOR STRUCTURES

EXTERIOR STRUCTURES

Vertical Circulation• Cores = service cores = risers

• Contains :

– Elevator shaf ts.

– Elevator lobbies.

– Main & escape stairways, ramp.

– Riser-ducts.

– Toilets.

– Other service rooms.

• Elevators = MAIN ver t ical circulation system.

Configuration

At initial design stage, designer DETERMINES:

• Buildable net rentable areas (NRA)

• Gross floor areas (GFA)

• Typical & atypical floor-plates

• Prepare a diagram + propose elevator configuration:

• No. of banks

• No. of stops

• Transfer floor(s)

Function of Service Core

Simply state that service is defined as those part of a building that

consists of the service lift, fire stair , Toilet, service riser duct .

Element of Service :

1. TOILET

2. FIRE STAIR.

3. SERVICE/FIRE ELEVATOR

4. RISER DUCT

1. TOILET

2. PLUMBING

3. DUCTING

4. SERVICE/FIRE LIFT

5. FIRE STAIR

Structure of Core

• If the building structure been

R.C.C , the core structure

should be shear wall. In this

case core structure may not be

steel structure.

• If the building structure been

steel , the core structure

should be steel structure. In

this case core structure may

be R.C.C structure.

• If the building structure been

Composite ,the core structure

should be shear wall. In this

case core structure may not be

steel structure

diagonal

connection

vertical connection

Typology of core

1. central core

2. Split core

3. End core

4. Atrium core

configuration

plan

Single tenant

Double tenant

Multiple tenant

Core design

Service Core & Building Economy

• Minimization of material costs• Optimization of core

geometry• Minimization of core area• Minimization of construction

time

POSITION OF CORE:

should be located on the east & west side of the building.

With both cores on hot sides, they provide Buffer zone.

should be on the periphery of the usable floor space. Because--

1. Mechanical lighting

2. Mechanical ventilation

c

v

v

c

v

Cantilevered system

Slabs are

supported by

the core

individually.

Suspended system

c

v

v

c

v

slabs are

suspended at the

top of the core, so

loads of all floor

act from the top of

the core.

central core :

LOAD TRANSFER

core

Spilt core :

core

core

Off center core :

core

Service-core layout & space requirements :

Benefits of a peripheral core position:

• No fire-fighting pressurization duct is needed

• Good view out

• Natural ventilation

• Natural sunlight

• A safer building in the event of total power failure

• Solar-buffers & energy savings

Service-core layout & space requirements :

• Elevator car sizes & shapes

• Elevator door types & sizes - common widths 1.1 m or 1.2m

• Elevator shafts - are according to car shapes & sizes, and

door sizes. Sufficient air around cars & counterweights should

be provided to minimize buffeting & air-borne noise during

operation.

• Elevator core & lobby planning - ‘outward facing’ elevators VS

‘inward facing’ elevators.

Department of Architecture

Hajee Mohammad Danesh Science & Technology University