Simplified Procedures for Seismic Design of Nonstructural Components and Assessment of Current Code Provisions

Keywords: National Earthquake Hazards Reduction Program, Code Provisions, Response Modification Factors, Earthquake Resistant Design, NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings 1991 edition, Equipment, Seismic Force Coefficients, Nonstructural Elements, and Code Recommendations.

Abstract: The detailed seismic design provisions for nonstructural components in buildings were first proposed in the 1978 ATC-03 report. These have been adopted with some minor changes by 1991 NEHRP Recommended Provisions. These provisions are here critically evaluated, and improved procedures which incorporate the dynamic characteristics of the supporting structure as well as nonstructural components have been proposed. The basic format of the proposed procedure for calculating the seismic force is the same as in the NEHRP Provisions, except that the seismic force coefficients are now defined on a more rational basis. The effect of the inelastic behavior of the supporting structure on the seismic coefficients is incorporated through response modification factor R, as is done in the NEHRP Provisions. Simplified methods are also presented to calculate the frequencies, mode shapes and other modal quantities required for calculating the seismic coefficients. The seismic design forces for different architectural components and flexible mechanical equipment, placed in buildings of different heights, periods and ductility, calculated according to the 1991 NEHRP Provisions, Tri-services Manuals and 1991 Uniform Building Code, are compared with the forces calculated by the proposed procedure to demonstrate the importance of various parameters of the structural and nonstructural systems in the calculation of the design forces.