To check The Dead load as per Staad for no of floors

1. Self weight (columns,beams and shear walls for the entire building)
2. Brickwall over the exterior beams except on shear wall only are added.
3. The dead load on slab- Self weight of slab+Finish+Construction load +15% for furniture, staircase, water tank etc is added with an intensity of 6KN/Sq.m.

A manual check for these items are carried out as:

  • Dead load: Area of floor x no. of floors x intensity of load
  • Brickwall load:
    Total length of beam in one floor =
    Load per floor =
    Load due to brickwall alround exterior beams =
    Load due to Parapet 1.0 m height of 4.5” wall=
    Total dead load due to brickwall =
  • SELF WEIGHT OF:
    • COLUMNS =
    • Beams for all floors
    • Shear wall:
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HOW TO DO MANUAL CHECK AGAINST STAAD RESULTS FOR SEISMIC FORCES?

Example
The structure is 36x21m and is symmetrical in x and Z direction as well as in vertical elevation and its total height from the footing is 74m.(21 storey)

The building is in Zone III and the time period as per IS 1893-2002(PartI) for infill is taken 0.09h/√d.

After analysis through STAADPRO the followings check is carried out to verify and check the results between manual calculation and the software results.
————————————————————————————————-

A. TIME PERIOD:

As per IS CODE 1893-2002(Part I) T =0.09h/ √d where d is the direction along the EQ forces.
Tx =0.09×74/ √36 =1.11 Sec.
Tz =0.09h/ √21 =1.453 Sec.

The output of STAADPRO is

TIME PERIOD FOR X 1893 LOADING = 1.11000 SEC
TIME PERIOD FOR Z 1893 LOADING = 1.45333 SEC
******************************************************************************************

Manual checking of Staadpro output

LOADS:

Correct assessment of loads both dead and live loads are important since excessive assumed loads may lead to uneconomical member sizes and footing sizes. Also excessive loads will be adding more weight in the case of seismic forces.
In order to have equilibrium i.e .ΣV=0 under the Load case DEAD LOAD calculate the total dead load on all floor slabs and check it against the output by the program.

METHOD TO CHECK:

Using a single support for the whole structure RUN the ANALYSIS and find out the total support reaction in Y axis i.e FY from the output of the program. Check whether the above two values are in agreement to the manually calculated values. If the results vary then there is some error or mistake took place while entering the input.
The same procedure can be carried out for the LIVE LOAD for both FLOOR LIVE LOAD and ROOF LIVE LOAD cases also. Continue reading Manual checking of Staadpro output

Manual checking of Staadpro inputs

Model checking

It is important to check the UNITS at every stage while modeling since it may lead to a unexpected error in the output. While modeling use of length units may be in meter for beam, column and plate and while entering the properties it is usual practice to make use of either mms or inch unit . While inputting the LOADS on members check the UNIT system is in KN and meter system since the program continues to use the previous unit till it is changed.

Before inputting the LOADS to the structure facility is available in STAADPRO as per the screen shot.

  • Check Multiple Structures.

Some times by mistake the user would have without his knowledge created too many members and structure. Better use this tool menu to remove the multiple structures. It is the responsibility of the applicator to verify that there exists only one structure and not more than it for any model.

Check for multiple structure in Staadpro
Check for multiple structure in Staadpro

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