Limitations of Equivalent Lateral Force Procedure for Nonbuilding Petrochemical Structure Configurations

Abstract

The Equivalent Lateral Force Procedure (ELFP), as outlined in ASCE 7, is a method for developing and distributing equivalent static lateral loads on a structure to account for the horizontal seismic load effect. Other options, such as Modal Response Spectrum Analysis and Time History analysis, are more sophisticated and require more advanced analysis and more knowledge of structural dynamics. ELFP is meant for regular structures for which the fundamental period of vibration is dominant in the mass participation. Many typical nonbuilding structures are not regular and have higher participation of higher modes of vibration. This paper outlines the limitations of ELFP for certain nonbuilding petrochemical structure configurations. It provides recommendations for analysis of typical petrochemical structures that are subjected to seismic loading. In addition, it defines procedures used to identify typical petrochemical structure configurations that are outside the limitations of the ELFP This paper not only identifies the major considerations for using the ELFP for nonbuilding structures and makes recommendations for the mitigation of impacts due to these considerations.