NEHRP Clearinghouse

Simplified Methods of Analysis for Earthquake Resistant Design of Buildings.
Cruz, E. F.; Chopra, A. K.
National Science Foundation, Washington, DC., February 1985, 260 p.
Identifying Number(s)
In Part I, the accuracy of the response spectrum analysis (RSA) for estimating the maximum response of a building directly from the earthquake design spectrum is evaluated with the objective of developing better simplified analysis procedures suitable for preliminary design of buildings and for inclusion in building codes. In Part II, recognizing that the earthquake response of many buildings can be estimated by considering only the first two vibration modes in the response spectrum analysis (RSA) procedure, a simplified response spectrum analysis (SRSA) procedure is presented. The SRSA method should be very useful in practical application because, although much simpler than the RSA method, it provides very similar estimates of design forces for many buildings. In Part III, formulas for base shear, height-wise distribution of lateral forces, and computation of overturning moments specified in three design documents -- Uniform Building Code, Mexico's Federal District Building Code, and ATC-3 design provisions -- are evaluated in light of the results of dynamic analysis of buildings. It is demonstrated that these formulas do not properly recognize the effects of important building parameters which control the significance of higher mode contributions in the building response; an improved procedure, which does recognize them is presented. The procedure represents a major conceptual improvement over present building codes with very little increase in computational effort.
Buildings; Theses; Earthquake engineering; Earthquake resistant structures; Seismic effects; Spectrum analysis; Design