| This work on the development of simplified methods of analysis which are suitable for application to earthquake resistant design of buildings is organized in three parts.;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. With the development of the SRSA, a hierarchy of four analysis procedures to determine the earthquake forces are available to the building designer: code-type procedure, SRSA, RSA, and RHA--response history analysis. The criteria presented to evaluate the results from each of procedure, and to decide whether it is necessary to improve results by proceeding to the next procedure in the hierarchy, utilize all the preceding computations and are therefore convenient.;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 recognizes the influence of these parameters, to compute the earthquake forces for the initial, preliminary design of buildings is presented. (Abstract shortened with permission of author.);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. It is demonstrated that: (1) For a fixed fundamental period T(,1) of the building, the response contributions of the higher vibration modes increase, and consequently the errors in the RSA results increase, with decreasing beam-to-column stiffness ratio p. (2) For a fixed p, the response contributions of the higher vibration modes increase, and consequently the errors in the RSA results increase, with increasing T(,1), in the medium- and long-period regions of the design spectrum. (3) The RSA results are accurate enough for design applications. |
