Modelling of 25 storey building with the specified properties using ETABS

que 1

Aim -to model and analyse 25 storey building with given specification and to cross check the parameter as per IS 1893 provision

Procedure-

• open the tabs software
• click the file menu and choose to create a new model option
• after choosing a new model a dialogue box will appear as model initialisation

• Choose the building sitting option and select the display unit and codes
• after model initialisation selected the greed and story input from the new model quick template dialogue box
• in this dialogue choose grade spacing and custom storage data which is used to provide the input specified a above
• enter data at a distance of 4 m and why grade data as 4 at a distance of 4 m

• Select material properties under the define tab
• define the materials of concrete M30 grade and steel of transverse and forcement as 415 grade and longitudinal reinforced as 500 grade

• Select the section properties under the define tab
• click on the frame section and create a new property as a beam and input the values as 300X 400 mm

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• After the define properties for the column as 800 into 800 and slab thickness as 150 mm

• Using the membrane property slab size 150 mm has been added to the list membrane property will help to consider on this lab weights and floor weds in analysis of structure while nose stiveness component of flange advantage are considered during calculation

• Now draw a column of size 800 into 800 mm at the intersection of the horizontal and vertical grid and beams with quick draw tool keeping all stories on

• Beams drawn using quick draw beam tool keeping all the stories on

• Using the quick draw floor option all the slabs have been model the keeping similar stories on

• Select assign and click on joint select the support
• fixed the pin supporter at the base

• Now define the load pattern click on the define and click on a load pattern
• define the loads like dead load live load break load earthquake load in X direction and positive X and negative action and same loads in the wire direction also mention is code of respective loads

• Click on modified at run load set range from ways to 25th story and seismic zone factor as 0.36 importance factor 1.25 and time period of 0.5 second

• Do the same for all the earthquake loads
• assign the loads and select similar stories
• click on sell load under the assign tab
• click on live load and give value as 3 kNewton per sq metre
• click on apply

• for the roof we will take only 50% of the live load

• Similarly add new load of 10 kN/m2 on the beams
• for that select all the beam from select object type beam
• go to the frame load and click on the distributed load and enter the value as 10 kN/m2

• Now go to the mass source of from the define tab
• modify the mass percent tick mark the required
• add load at load pattern and assign to the model

• Define the load cases click on the combination
• click on the add default design combos

• Now create the diagragam to the assign tab then shell and select difragum

• click on ok

• Analyse the model using analyse option then click on check model the model is structure is verified without errors and warnings

• Using analyse Run analysis the model is analysed and the deflection pattern are cross checkerologically it is understood that the worked a model previous reliable result

Result -

• now click on a display >show table> analysis result >a structure output> model information> model periods and frequences
• the time period for fundamental mode 1Y direction and fundamental mode 1x direction are noted from the table shown below

• Tx1 equal to 3.746 second and t y 1 equal to 3.913 second
• Display> show table >analysis result >structure output> model information >model participation mass ratios
• from the table the natural time period for more one and torsional dof is shown below

• When we add the three mood mass ratio we get 0.9044 which means first three mode of seismic oscillation contribute more than 65% of building weight as per Etab analysis
• the storey drift from servicebility based
• share case is tabulated from the following toolpath
• go to display >storage response plot
• keeping load case to EQY and switch into maximum storage dripto the maximum drift value is 0.0020
  

• So as per the clause 7.11.1.1 the maximum inter storage drift is melted to 0.004 for each storey height but our value is 0.0 020 which is within the code limit
• Conclusion the modelling is completed and analysed in etab .the result are within given ranges