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Dear fawad najam! The methodology for seismic design has been radically changed in ASCE7-05 from that used in earlier codes like UBC 1997,the governing parameter for development of response spectrum are now the ss (short period accelaeration) and s1(one second spectral acceleration) ss and s1 can be derived from the peak ground acceleration(PGA) using empirical relationshops based on performance level(EUROCODE 8).

In general, this issue is controlled by relevant clause of contract agreement. Following are the possible options that may be or might have been specified in the contract:- a. Demolition & recasting, in case actual strength falls MORE than a certain percent below the required concrete strength b. Strength evaluation of actual structure, according to applicable design code & acceptability or rejection of structure accordingly. c. Rarely, there might also be an option to strengthen the structure (using conventional or advanced strengthening techniques & materials) to the required level (where possible). Regards.

The existing Building Code of Pakistan (BCP) enforces a typical short-period shaped, UBC 97-based response spectrum which is a function of seismic coefficients Ca and Cv. These coefficients are further dependent on seismic zone factor (Z) and soil profile type. The BCP provides a table for seismic zones derived from a relatively recent PSHA study for all tehsils in the country, however, it doesnt provide the Standard Soil Profile Type Map to be used in conjunction with seismic zones. Is there any standard soil profile type map (or Vs30 map) for Pakistan? There are few individual studies on this topic, however, I am interested in a widely-accepted definition/assumption of soil profile types down to tehsil level. Thanks Fawad

Fawad, You can also find values of Ss and S1 for famous Pakistani cities in IBC Overseas Building Reference. See the discussion below: Thanks.

Yes, why not, who is stopping you?

If you are asking about possibility of designing a single slab of given dimensions, theoretically it can be. Practically however such a large slab will have undesirably high self-weight and deflection, if designed without beams. Self-weight as well as deflection can be controlled by providing beams along outer edges & at suitable intervals parallel to short span of the slab for reducing required thickness of slab from deflection point of view. Regards.