MANUAL PROGRAM FOR USE IN ETABS V 8.26 SEISMIC ANALYSIS OF STRUCTURES

Caiza Pablo Sanchez, M.Sc. Eng

pcaiza@espe.edu.ec

Paul E. Guerrero D. paul_ed_guerrero@hotmail.com

Research Center, CEINCI-ESPE

ABSTRACT

Standard parameters are set used by the program

ETABS through a very simple structure. Then you rebuild the same structure but step by step in order to manually enter those characteristics that included further give full basic model. Then include 2 types of dynamic analysis, static and modal equivalent spectral CEC2000 following the recommendations for what you use a more complicated model. Finally, it includes improvements such as ladders, foundation, slab on grade, but fundamentally reinforced walls with and without heads, and the latter with openings.

1. INTRODUCTION

Programs such as ETABS includes a growing number of technical improvements to the design of structures, many of which are regarded as standard. In order to determine these parameters is therefore required to generate a first structure as automatically as possible. On this basis it will rebuild the same structure but this time including manually each said improvements. This way you will gain knowledge and confidence about the program which will increase the complexity of the models. Is continued with the inclusion of seismic analysis such as static and modal spectral equivalent according CEC2000. Subsequently insists geometric model refinement by including stairs, foundation and slab on grade. Finally there is a new structural element: reinforced walls, there are two types: with and without heads, in the latter, in addition, take into account important details such as window and door openings.

It is emphasized, however, considered that the most important part of this manual

is the inclusion of the slab in the traditional models of beams and columns adapted for use in seismic analysis. The handling of this item is very delicate because on one hand commonly or very little is known of him or simply does not know and partly because the country seismic analysis is required and it must be considered forays into the plastic range.

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Two. REFERENCE MODEL GEOMETRY 2.1 PROPOSAL

In order to show the features that are standard program develops a simple model. It is a reinforced concrete three-dimensional structure of a flat 2.7 m high and single span of 4.5 meters horizontally both X and Y. It includes a two-way lightened slab.

2.2 MODELING IN PROGRAM

In ETABS, the first step to be taken is to define the units you want to work, for exercise change the units to tonnes and meters:

To start with a new project click the icon to generate new models:

A first screen appears that indicates whether to use the features of Chose.edb prebuilt models, or model Default.edb kept on file should be in the directory of ETABS. Press "No":

DEFINITION 2.2.1 MOTION GEOMETRY Fill the screen as shown below:

To create slabs lightened bidirectional press the icon at the bottom of the screen "Waffle Slab":

Fill the screen that opens as follows:

Press the OK button, to return to the previous screen, again OK: Shown below graphically the result of using this simplified instruction sequence, the colors differ from preset by the program is that we found it necessary to modify items created can be seen in a better way.

2.3 FUNCTIONS USED BY AUTOMATICALLY ETABS

To learn the different functions used automatically by ETABS for creating this structure, review the properties of its elements, for this move the mouse cursor over the central area of the slab, without pointing to other elements such as ribs and beams and press the right mouse button: Note that open the tab "Assignments".

The properties are assigned on this screen:

The slab is assigned a standard section called "SLAB1". It behaves as a rigid diaphragm. The local axis 1 is the standard. No stiffness modifiers. He has not been assigned a "Pier" or "Spandrel". No springs or mass per area. Automatically be split into:

o Intersections with beams and measuring lines, o Edges of walls and ramps and o Lines.

These latter options are for analysis of the structure, but the results are displayed for all the slab as a single unit, without subdivisions.

The maximum size of the mesh is 1.5 meters. It belongs to a group called "ALL".

Close this window and go with the mouse cursor to one corner of the slab, beams and avoid nerves again. Press the right mouse button.

Also here is open the tab "Assignments". There is a similar to the previous screen. However this time it is in the head macizados columns. In this case the macizado called "drop1" and is located in the lower left corner of the plan view of the model. Now point the mouse cursor to one of the beams and press the button again right:

Each of the items shown are properties that can be changed. The large number of properties gives great flexibility in the analysis. The default values are:

Section type "ConcBm" There is a special beam moments resistant (valid property for metallic

structures). The lengths of intersection with other elements are automatically calculated but

not considered stiff. The reference point of this element is at the top center of its cross section

and it has no distance from meshing baselines or reference. No local axes have changed. No change in compensation rigidities. No property modifiers. No tension and compression limits. No link properties. No plastic hinges.

Other options are still missing those seen at the end of the following screen:

These properties are:

This beam is not part of a wall column "Pier" a wall or beam "Spandrel". No linear springs or linear mass. It autodivide (only for analysis but not for the results) in points, nodes and

edges. Mesh is used for the floors. It is part of a group called "ALL".

Three. STEP BY STEP MODEL

It is interesting at this point to re-create the same model but step by step in order to handle the different tools available in ETABS. Additionally will be used to add further information. GEOMETRY 3.1 PROPOSAL:

It is a reinforced concrete three-dimensional structure of a flat 2.7 m high and single span of 4.5 meters horizontally both X and Y. It includes a two-way lightened slab.

Table 1 Characteristics of the structural elements

ELEMENT FEATURES

BEAM BASE = HEIGHT = 35cms 30cms COLUMN BASE = HEIGHT = 35cms 35cms

SLAB Lightened type, thickness 20 cm, with tile compression of 5 cm (nerves of 15 cm high)

Table 2 Characteristics of materials

MATERIAL FEATURES CONCRETE f'c = 210 kg/cm2, E = 210 = 173897 12000 Kg/cm2

STEEL fy = 4200 kg/cm2

3.2 MODELING IN PROGRAM

Begin by reviewing the units are right: tons and meters and then press the icon to create new models. In the screen that opens answer "No". DEFINITION 3.2.1 MOTION GEOMETRY Then fill the new screen in the same way as at the beginning of this manual but finally, do not enter any additional box and just press "OK". You get only the reference network.

3.2.2 DEFINITION OF MATERIALS AND STRUCTURAL SECTIONS In the next step define the structure materials. Follow the script that follows:

MENU OPTION Suboption

Sets Material Properties ... Modify / Show Material ... (Previously CONC check the box is

highlighted)

Fill the box that opens as follows:

Note that the units are tons and meters so a value such as f'c = 210 kg/cm2 equal to f'c = 2100 TON/M2. To exit press the OK button in the preview screen and OK again. Now define sections of structural elements:

MENU OPTION Suboption Sets Frame Sections ... ---

In the new screen delete all previously defined sections. To do check all elements of the picture on the left and then press the "Delete Property". It erased all sections except one that the program uses as standard section.

Then press the right eyebrow of the second box on which is written "Add I / Wide Flange". It displays a list in which to highlight "Add rectangle". Another screen appears, which must be completed as follows:

By placing such equipment "CONC" activated the "Reinforcement". Press to get the following screen and modify it as shown below:

Press the OK button to return to the previous screen. Now press the "Set Modifiers" and change the inertia about the axis 3 as indicated, this step indicates the allocation of inertia to the beam cracked defined:

Press the OK button to return to the previous screen. And OK again to get the home screen. Repeat this procedure to create the nerves:

Note that pressing the button "Reinforcement" as with the button "Set Modifiers ..." must complete the appropriate screens identically to what has been done to the beam.

The procedure for defining the columns is similar:

Note that have been modified rigidities of inertia about the axes 2 and 3 local 0.8. Now define the slab section. Use the following script:

MENU OPTION Suboption

Sets Wall / Slab / Deck Sections ...

You must press the right eyebrow of box "Add New Deck" and choose "Add New Slab"

Fill the box appears as follows:

To prevent the membrane collaborate with the edge beam as an infinitely long wing press "Set Modifiers ..." and change the rigidities as indicated:

Similarly create a section "Macizado" identical to "SLAB" including stiffness modifiers but with thickness0.15 meters.

3.2.3 SECTIONS ALLOCATION MODEL (BEAMS, COLUMNS, SLABS) For beams use the icon:

In view of the level3.00 meters, Check the auxiliary window that has appeared on your monitor so that the section to be used is that of a beam V30x35. Then point the mouse to the upper left corner of the mesh and drag to the bottom right corner, creating a region covering the rafters. The beams are generated automatically:

To generate the columns use the following icon:

Likewise use level plan view 3.0 meters and create a region encompassing the location of the columns. Do not forget that the auxiliary window should indicate C35x35.

Now add the nerves. Use the following icon:

The auxiliary window that appears to be amended as follows:

In a plan view point the mouse to the upper left corner of the mesh and drag to the lower right corner marking the region where the nerves are located.

Then, modify the last data of the auxiliary window "Approx. Orientation "to" Parallel to Y or R "and repeat the above procedure by marking the region where the nerves are located in the direction Y. Finally you will get a window similar to the following:

To exit the generation of "nerves", press on the keyboard "Esc". To include tile compression also use the following icon in the left column of the screen:

Auxiliary window appears. Make sure you use the "SLAB". In view of the level 3.0 meters click the left mouse button on the knot of the column in the upper left corner and hold to drag the column node in the lower right corner.

Similarly generates the macizados, but using the "Macizado". The macizado only last until first rib from the columns. For the mouse traps exactly the position of the intersections the following icon in the left column bottom must be activated:

3.2.4 IMPROVEMENTS TO MODEL To generate the slab flown check all four edges ("edges"). To do this you point the mouse on each side inside the perimeter of the slab. Then use the following script:

MENU OPTION Suboption Edit Expand / Shrink Areas ... Offset Value = 0.15

At the end you will get a graph like this:

To create a rigid diaphragm, mark the five elements generated plate. To do this use the following script:

MENU OPTION Suboption

Select By Wall / Slab / Deck Sections Check "SLAB" and "Macizado" ok

Then use the following icon:

The following window appears where already written diaphragm renamed "Piso1" and additionally used the "Add New Diaphragm" finally you must press "OK" to create the diaphragm:

For the ruffles act together with nerves and slab slab should be divided into at least 2 x 2 mesh for this case, as this is only an example 9x9 mesh divide into divisions ie about 0.5 x 0.5 meters"It is advisable only in poor divide because the run 2x2 model runs in less time" to this framework the slab and keep the instruction sequence shown below:

MENU OPTION Suboption Edit Mesh Areas Mesh Quads / Triangles into 9 by 9

To match the characteristics of the model that was built at the beginning of this manual and only need to change the constraints of the nodes of the base of the structure. To do check these knots and use the following icon:

Fill the screen appears as follows:

A final feature included are still stiff ends of beams and columns. To mark all these elements use the following icon found in the left column of the screen:

Then click on the following icon located in the second row of icons at the top of the screen:

In the window that opens fill the data as follows:

3.2.5 DEFINITION OF CHARGES You must define the following basic states:

NAME FEATURES PP Weight of the structural elements

AMUERTA Permanent loads such as finishes and walls VIVA Loads temporary

SISMOX Static seismic loading in X SISMOY Static seismic load in Y direction

In the program use the following script:

MENU OPTION Suboption Sets Load Cases ... Modification and entering charges

The basic loads window should be as follows:

Note that for seismic loads in the "Auto Lateral Load" appears "None".

In this first model will be used as the equivalent elastic method CEC2000 but will explain later. Therefore modify these loads first so that the "Auto Lateral Load" switch to "User Coefficient". At this point will activate the right button "Modify Lateral Load" which should then press to change the data as follows:

For loading "SISMOX" corresponds to earthquake in X

For the earthquake in Y direction use similar data except that the direction and eccentricity "And Dir + ECCEN X".

The magnitudes of additional permanent load "AMUERTA" and "LIVE" are listed inTable 3:

Table 3 Magnitude of vertical basic charges

LOAD MAGNITUDE AMUERTA 0.3 t/m2

VIVA 0.2 t/m2 3.2.6 ALLOCATION OF CHARGES To assign selections loads the "SLAB" (Select - By Wall / Slab / Deck sections ... - LOSA) and use the following icon:

The following screen appears that has been modified for loading data "AMUERTA":

Follow a similar procedure for loading "VIVA" but using the magnitude of 0.2 t/m2.

For combinations verify that you are designing the ACI 318-99 code. Use the following script:

MENU OPTION Suboption Options Preferences Concrete Frame Design ...

The following window appears which shows as first property the design code is the ACI 318-99:

Press "OK" to exit this screen. To create combinations use the following script:

MENU OPTION Suboption Design Concrete Frame Design Select Design Combo ...

As you can see the combinations are already created and as mentioned before correspond to those defined by ACI 318-99

Let the combination "DCON2", for it should be noted the name and pressed the button Show, will be the following:

To close the window press OK button. You can now check that the design combinations are ready using the following script:

MENU OPTION Suboption Sets Load Combinations ... ---

To exit press the OK button. 3.2.7 PROGRAM IMPLEMENTATION AND ANALYSIS The model is ready and the program is run using the following icon in the top bar of the screen:

In the auxiliary window that opens press the "Run" button. In case you have not recorded yet the model should do so now. Use any name for the file, such as "Model 2". Immediately you get a view like this that shows the deformed structure.

To see the results of internal forces in the elements use the icon to the right of the first row of icons:

Press the right eyebrow, and in the box that appears choose "Frame / Pier / Spandrel Forces ...". You get pictures similar to the following:

Note that for the combination "DCON2" get moments around the local axis 3 "Moment 3 -3 ". Additionally in the "Options" is marked "Fill Diagram", which get filled moments drawing color. If you remove this option, you can use "Show Values on Diagram" allowing you to see the values of the moments. Pressing the OK button will display like this:

To see more detailed results point the mouse to one of the elements, such as a beam, check the axle beam 1 and press the right button. You will get the following results:

Note that the results are for "DCON2" but may vary to other loads directly in this window. To the right at the top also is marked to note that maximum values, but if you choose the other option "Scroll for Values" can for example move the mouse over the diagram and obtain values at other points. 3.2.8 STRUCTURAL DESIGN: To make the design follow the following sequence of choices:

MENU OPTION Suboption Design Concrete Frame Design Start Design / Check of Structure

As best suggestion is dialed before the beams and columns to obtain the longitudinal reinforcement of these elements.

To view the results will change the units to inches. Shows the longitudinal reinforcement.

For assembly of the brackets use the following script:

MENU OPTION Suboption Design Concrete Frame Design Display Design Info ...

In the window that opens choose "Shear Reinforcing" as follows:

To see the results press the "OK" button. Values are cm2/cm, ie to calculate the area of the stirrups multiply the previous value by the spacing between stirrups.

For more information point your mouse to one of the structural elements, such as a column, and press the right button. Get windows like this:

Use the buttons at the bottom to provide design information. As a final observation to compare the results with the traditional model consisting of beams and columns can be seen that the beams absorb less load and therefore have lower internal forces. It is therefore advisable to reduce the resistance to bending about the local axis 3 of the nerves. This article is considered acceptable to reduce this parameter to 25%. April. MODAL ANALYSIS SPECTRAL

To describe this type of analysis will make use of the following structure: GEOMETRY 4.1 PROPOSAL

Three-dimensional structure of two windows in both directions horizontal and two stories high, as shown inFigure 1.

Figure 1 dimensional model

The material is reinforced concrete: fc = 210 Kg/cm2, fy = 4200 kg/cm2 and Ec = f'c = 173897 12000 Kg/cm2.

The sections of structural elements are as described in Table April.

Table 4 Characteristics of the structural elements

ELEMENT FEATURES

BEAM BASE = HEIGHT = 35cms 30cms COLUMN BASE = HEIGHT = 35cms 35cms

SLAB Lightened, 20 cm total thickness: tile compression of 5 cm and nerves of 15 cm high.

Regarding static loads are dead weight, dead additional, live, xy earthquake earthquake magnitudes being loads additional "dead" and "alive" indicated in Table May.

Table 5 Loads gravitational

TYPE MAGNITUDE (kg/m2)

AMUERTA 280 VIVA 200

For analyzing spectral mode spectrum is used by the given design CEC2000, as shown inTable 6:

Table 6 Parameters of the design spectrum according CEC2000

FACTOR DESCRIPTION VALUE

C Profile design spectrum

CmT

SSC =

25.15.0

variable

S Soil type coefficient 1.5 (= S3) Cm Maximum value of C according to soil type 2.8 T Vibration periods variable Z Area Factor 0.4 I Important factor 1.0 R Reduction factor structural response 10

P Coefficient plant structural configuration 1.0

E Coefficient elevation structural configuration 1.0

The spectrum is a plot of maximum acceleration of the structure with respect to its period. In Table 7 are given the values of C are used and the way in Figure Two.

Table 7 Values of factor C

T C 0 2.80

0.821 2.80 0.9 2.55 1 2.30

1.1 2.09 1.2 1.91 1.3 1.77 1.4 1.64 1.5 1.53 1.6 1.44

1.7 1.35 1.8 1.28 1.9 1.21 2 1.15

2.5 0.92 3 0.77

3.5 0.66 4 0.57

4.5 0.51 4.6 0.50 5 0.50

Figure 2 Factor C according CEC2000

Coefficient, gR

IZEp

***

*

Needed to transform the acceleration factor is 0.39 C

For spectral modal analysis is also necessary to consider the following:

Mass: only used for permanent loading elements Buffer: use a general value of 5%. Number of ways: the need to obtain a share factor modal mass of at least 90%

of the total mass. If the models are used for plant concentrated mass which is known for this example requires minimum 6.

Since earthquakes come in any direction will be a combination directional senses X and Y using the square root of the sum of squares. This example does not consider the vertical component of the earthquake because there elements such as overhangs, may be affected. Further according to CEC2000 torque is required to consider if necessary accidental and p-delta effect. 4.2. MODELING IN PROGRAM

Press the icon again model ("New Model"). The following screen appears:

0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 1 2 3 4 5

Fact

or C

Periodo T (seg)

Press "Choose.edb". In the new screen choose the file name before you've made in ETABS (if you have followed this article is "Model 2") and press the OK button. The following screen appears that has been modified with new data:

4.2.1 DEFINITION MOTION GEOMETRY

Note that you have enabled the option "Custom Grid Spacing". Press the down button immediately to the right "Edit Grid ...". Gets the next screen where you have already modified the right elements:

To return to the previous window, press the OK button. In that window click the icon "Waffle Slab" for the window shown below and in which it has already changed the data available:

Respect to the cantilevers ("Overhangs") are slab areas beyond the axis lines. These ends have at least the same size on the sides of the columns divided by two, which is the value used. Regarding the macizados and nerves ("Drop Panels and Ribs") this model does not have macizados and nerves are spaced0.5 meters. Regarding restrictions on the base ("Restraints at Bottom") are recessed ("Fixed"). Additionally create rigid floor diaphragms.

On the right side of the window shows that due to the structural and load definitions made on a "Model 2" they can be used directly in this new model.

Press the OK button to exit to the previous window again press the OK button.

You will get a screen similar to the following:

To include dropped beams should work on a plan view: Change the box to the bottom of the screen "One Story" to "Similar Stories". Check all items that match the axes of the structure. Assign Items marked the "V30x35".

To complete the model will eventually be assigned to all the elements, extreme rigid stiffness coefficient of 0.5.

MODAL ANALYSIS SPECTRAL 4.2.2

To add modal spectral analysis use the following script:

MENU OPTION Suboption

Sets Response Spectrum Function ... Highlight "Add User Spectrum"

You will get the following screen should be exploited Add User Spectrum

A screen appears in which you must fill data period and acceleration of the design spectrum, obtained from the CEC2000. In this case, enter periods and coefficients C, escalndose latter subsequently to obtain accelerations. The window stay as follows:

Press the OK button to return to the previous window OK again.

Now use the following sequence of options:

MENU OPTION Suboption

Sets Response Spectrum Cases ... Add New Spectrum ...

Fill the window that appears as shown. Note specifically that the combination does not include directional vertical component, since this, as mentioned above, it is important only in the presence of overhangs.

Press the OK button to return to the previous window again OK.

To include the mass, not only the weight of the elements, but also the load "AMUERTA" use the following sequence of options:

MENU OPTION Suboption Sets Mass Source ... ---

The following window appears that has already been completed with the necessary data:

To add the number of vibration modes and also include the p-delta effect use the following script:

MENU OPTION Suboption Analyze Set Analysis Options ... ---

It opens the next screen you already stated that you want not only the dynamic analysis but also include the p-delta effect.

For dynamic analysis options press the "Set Dynamic Parameters ...". Change the window that opens as follows:

Press the OK button to return to the previous window press "Set P-Delta Parameters ...". Change the window as follows:

Press the OK button to return to the previous window OK again. 4.3 RESULTS OF DESIGN

The model is complete including modal spectral analysis. You can solve it and design it, here are the results of the design for both the longitudinal reinforcement to the cross. It must be remembered that to visualize design data should change the units to tons and centimeters. Longitudinal reinforcement:

To check the design, select a column which is at the intersection of the axes 1 and A and the right mouse button design see the results on the screen as follows:

As for the transverse reinforcement can see the following results:

To see more details of the design process can be repeated highlight the item and press the right mouse button. May. LADDER, SLAB FOUNDATION AND INCLINED. 5.1 LADDER.

Generate first opening of the slab. This panel will be in the 1 to 2-AB attached to the shaft 2 in a width of 2 meters and a B axis over 3 meters. Work on the plan view of the second floor and make sure the box in the bottom center of the screen says "Similar Stories".

Delete the nerves. For example, to remove the ribs along the X axis tick mark them and additionally also on the nerve perpendicular edge of the opening of the slab. Then use the following script:

MENU OPTION Suboption Edit Divide Lines ... ---

Fill the window that opens as follows:

Press the OK button. Then highlight the sections of nerves to delete and press "Delete". To clear sense nerves and work similarly.

The nerves of the edges of the opening will be divided into a number of segments. For re-unite, mark and then use:

MENU OPTION Suboption Edit Join Lines ---

To remove the tile compression: Generate a new element section shell but "OPENING".

You then build a mesh auxiliary axes of the stairs: In the plan view of the second floor, find an empty space, point the mouse and click with your right mouse button. A window with options. Choose "Create Concerning Lines on Plan ...".

The mouse pointer changes to an arrow with black elongated that should mark the right edge of the opening of the slab at a distance of 1.0 meter to the left from the intersection of the axes 2 and B and the upper left, these two reference axes are on the axis 2. To exit the option of generating baselines press the "Esc".

These new lines can be seen in the light of the axis B.

To define the level of the breaks again point to an empty place and click the right mouse button. Now use the "Edit Reference Planes ...". The following window appears that has already been modified:

Press the OK button and in the elevation view axis 2 can observe the auxiliary mesh.

Next draw the axes Frame elements of the ladder. Use the following icon in the left column of the screen:

Use V30x35 section. You will get a screen like this:

Now should "extend" the elements of the ladder frame to become Shell elements. First press the button as if it were to generate a slab.

And on the screen that drops down select "Slab"

Check all elements of the ladder. Then use the following script:

MENU OPTION Suboption Edit Extrude Lines to Areas ... ---

Modify the window that opens as follows:

Note that the Frame element is "extend" one meter in y (down) and is repeated twice.

Then you must delete one of the two elements of the incline Shell. On each floor in the upper clear on the right and on the left bottom. Do it in a 3D view. At the end you will get a screen similar to the following:

Finally you must assign a section to the ladder. Generate a new 12 cms thick and behavior as Shell and assign.

5.2 FOUNDATIONS. If isolated plinths are not enough, the usual alternative is the foundation grill. Use a section like the following:

In the "Reinforcement ..." change the coatings (like beam) in both the top and bottom to 0.08 m.

In the button "Set Modifiers ..." change the inertia of the section about the axis premises 3 of 0.8.

Then switch nodes restrictions floor level of the structure. First check all nodes, except the ladder knot off-axis B and assign the following restrictions:

Then generate the grid, in a similar manner as previously indicated for the beams.

Then highlight the beams of the grid and change the orientation of the local axis using the following icon in the second row at the top of the screen:

Fill the box appears as follows:

Press the OK button. Finally elastic springs need to include additional data: Effort soil admissible in this case is supposed to be 15 t/m2 To calculate the elastic stiffness of the spring representing the ground per meter length using the following equation:

vigaTbadmmlk **120 =

Where k / ml is the rigides per meter length, adm is the allowable stress t/m2 soil and bviga T is the width of the beam T foundation. In this example k / ml equals 1080 (U / ml) / ml. To enter this data redial all foundation beams and use the script that follows:

MENU OPTION Suboption Assign Frame / Line ... Line Springs ...

Fill the window that opens as follows:

Press the OK button.

PITCHED ROOF 5.3 To illustrate the use of sloping roofs will be added to the above structure in an inclined roof opening panel of stairs. This will be made of metal: C150x50x3 profiles, have slopes of 30% and the cover material is asbestos cement. Then define the new asbestos cement materials with a specific gravity of 1.8 t/m3, a mass of 0.19 T / (M3G) and a modulus of elasticity of 1.1 t/m2 E6.

Add on the other hand a section C150x50x3 steel and a shell of the new material and 5mm thick and 50mm membrane and bending.

Then insert a new floor using the following script:

MENU OPTION Suboption Edit Edit Story Data Insert Story ...

Modify the window that opens as follows:

Repeat the same procedure to create a flat name "Cumbrero" and high0.6 meters.

Bidders must provide baselines in the center of the span AB on axes 1 and 2. You can use as a reference the intersections of lines 1-A and 2-A, the "Create Reference Lines on Plan" and the box "deviations" (Offsets) filled in the following manner:

Then generate the structural framework so as to obtain a graph like this:

Note that the cover plate elements have been divided into 4X2 shells.

ARMED WALLS 5.4 To give a support to the stairs you build a reinforced concrete wall 10 cm thick (must define this section, and change the stiffness modifiers f11, f22 and f12 0.5).

Axis in the plane of section B assign created as follows:

It should be noted that the wall on each floor is divided into 4x4 parts, to this point the walls and divide by Mesh Areas ...

Note that the restrictions of the base of the wall have also been changed to correspond as part of the foundation knots. In order to design these elements should be assigned a name like "Piers" (columns) or "spandrels" (beams). To this end check all elements of the wall downstairs and use the following script:

MENU OPTION Suboption Assign Shell / Area Pier Label ...

The following window opens, where it is already entering the name for these selected items and is "P1".

To the second floor shell elements follow a similar procedure but name them "P2", do not forget to add this name by pressing the "Add New Name".

To include heads, must draw columns with the size of those heads and then assign the same name as "Piers" (wall element working as a column) than the rest of the wall shell elements. This example will draw an additional column to the left side of the wall current and assigned appropriate names for the following picture:

To assign these names, do not forget to mark the elements that are going to work and then use the following script:

MENU OPTION Suboption Assign Frame / Line Pier Label ...

Finally if the wall has openings (simply delete shell elements necessary), the shell above them work as beams, in this case a form of expression that includes not only the "Piers" but also "spandrels" is the one shown in the following figure:

The elements called "V1" are "spandrels". Right now perform structural analysis and then design the wall. Use the script:

MENU OPTION Suboption Design Shear Wall Design Start Design / Check of Structure

You will get a graph like this:

To see the results of the "spandrels" point the mouse to one of them and press

the right button:

It should be noted the complexity of the final model that has come to look, here is a three dimensional view where you can see clearly the sections used:

June. CONCLUSIONS Has developed a first model fashion ETABS automatically as possible in order to determine the program standards. Following the same pattern was repeated but including manually each of its characteristics. On this basis developed a new model which already included a seismic analysis such as modal spectral and added important details such as: stairs, foundation and sloping roofs. Finally, we included a reinforced wall, head first without, then with heads and finally with openings.

- This article on using ETABS follows the sequence: elemental structure complex structure.

- Presentation of different tools to solve real structures ETABS, starting with the most necessary to the relatively more sophisticated.

- Models include improvements to the seismic design according CEC2000. - Is not any analysis of results.