Experimental Investigation of P-Delta Effects to Collapse During Earthquakes

Results of tests on fifteen four-column frame specimens subjected to progressive unidirectional ground shaking up to collapse are analyzed. Test structure performance is compared with proposed drift limits for the minimization of P-∆ effects in highway bridge piers. The stability factor θ is found to be strongly related to the relative structural performance in this regard. Specimens for which values of θ are less than 0.25 satisfied the criterion proposed by the National Cooperative Highway Research Program (NCHRP) for at least a portion of their respective test schedule. The drift limit is violated prior to the final test, in which complete specimen collapse occurs.