A Comparison of Earthquake Building Code Regulations

It is important to constantly review the building codes that are currently being used in order to determine what improvements might be made. For example, the formulae for obtaining base shear, lateral force distribution and building period are continually being evaluated. Each year design force levels increase in order to meet regulations which reduce the likelihood of failure in the event of an earthquake. Buildings must be constructed stronger and this may result in more structural redundancies, some of which may be unnecessary. When a change to a code is proposed, the effect of this change on the variety of structural shapes and systems must be considered. For example, a code change could affect a two or three story concrete shear wall building much differently than a twenty story steel frame high rise. Rather than randomly increasing design levels or altering code requirements a code change should first be examined for effects on a representative set of structures. This examination procedure is the subject of this work where the set of structures has been designed by current building codes and can be used for comparative purposes in evaluating the overall usefulness of a proposed change and its value to certain structural systems.

The Seismology Committee of the Structural Engineers Association of Northern California (SEAONC) has studied a method which will standardize and simplify the procedure for examining the effect of proposed building code changes. The findings strongly indicate the need for the study of a typical or standard set of buildings which would include not only the general specifications for design of each building, but also several sets of completed designs done by use of the most widely used building codes of today. This proposal offers a simple procedure that can be utilized to compare the impact of a code change against a code with a known performance.