Seismic experimental study on a concrete pylon from a typical medium span cable-stayed bridge

摘要

According to the current seismic design codes of bridges in China, cable-stayed bridges have been usually required to remain elastic even subjected to strong earthquakes. However, the possibilities of pylon plastic behavior were revealed in recent earthquake damages. The lack of due diligence in the nonlinear seismic behavior of the pylon has caused a blurry understanding about the seismic performance of such widely built though less strong earthquake experienced structures. In light of this point, a 1/20 scaled concrete pylon model which from a typical medium span cable-stayed bridge was designed and tested on the shaking table longitudinally. The dynamic response and seismic behavior of the pylon were measured, evaluated and compared to reveal its vulnerable parts and nonlinear seismic performance. The results show that most parts of the concrete pylon remain elastic even under very strong excitations, which means a sufficient safety margin for current pylon longitudinal design. The most vulnerable parts of the pylon appeared first at the pylon bottom region, cracks opening and closing at the pylon bottom were observed during the test, and then extended to the lower column and middle column around the lower strut.