Civil Engineering/STAAD Pro


Hi Sir, I analysed 60mX40m RCC framed structure, 40m high for fixed support under soil conditions like Hard, Medium, Soft in STAAD Pro V8i. I analysed for zone V , earthquake resistant. the results concluded that the deflection for soft soil was higher compared to hard soil. i hope its correct yet if earthquake attacks hard soil then the same force is transfered to building. in case of soft soil the force transformation from soil to building is less. so i doubt that higher deflection must be for hard soil.. pls clear my confusion.. thanks in advance

Dear Manju

The PGA in soft soils is less than in hard soil due to plastic deformation in soft soils which occurs in lower PGAs. But the deflection in soft soils must be higher than in hard soils. But the earthquake effect on a specific structure is not equal in hard soil and soft one and it depends on period of vibration of the structure. A hard structure on a hard soil or a soft structure on a soft soil may experience amplification effect which must be take into serious consideration when designing a structure.

I am not really sure wether my response matches your problem. Dont hesitate to ask me further about any doubt you would have.


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Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

Sinam Consulting Engineers Co.

Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

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