Application of Response Spectrum Analysis of Multiply Supported System, with the Multi-Directional Excitations and Residual Rigid Response

In the seismic design of equipment and piping systems, it seems that precise response spectrum analysis method multiply supported systems with good accuracy does not spread, though there are many which subject different earthquake excitations. The Standard Review Plan 3.7.1 in United States, for example, recommends each support point be combined by absolute sum. However, this leads to excessive conservative response, is a problem analytical accuracy. Then, paper presents basic equation motion considering correlation between modes excitation directions residual rigid system receiving three-directional excitations X, Y Z. applied CCFS based on sophisticated random vibration theory Kiureghian, missing mass Regulatory Guide 1.92 Rev.2, synthesis multi-directional our previous work, purpose present evaluation formula multiple hope promote improvement guidelines systems.