Experimental studies on CSRDM specimen to validate the use of Ritz vectors for the response evaluation of structures subjected to multi-support excitation

•Ritz vector is used for the first time to analyze multi-support excitation problem.•Efficiency of Ritz vector over Eigen vector is studied.•Effect of spatial variation of ground motion in the responses are analyzed.•Experimental testing on CSRDM rod for multi-support excitation has been carried out.•The numerical formulation and their results have been compared with experimental results.