Primary Research On Rotating Characteristics Of Skew Bridge Under Earthquake Action

In recent years, with the flourishing development of China's highway construction, a large number of skewed bridges have emerged. Because of the better adaptability to road alignment and the higher driving comfort of skewed bridges, it is widely used in the highway at home and abroad. But in previous earthquakes, it is found that skewed bridges are more vulnerable to damage. Compared with straight bridges, the most significant damage characteristic of skewed bridge is the rotating tendency of deck around the vertical axis. In Wenchuan earthquake, the deck rotation of skewed bridge is prominent. The study of seismic performance of skew bridge is still not perfect, so this paper discusses the earthquake damage mechanism of skewed bridges.The earthquake damage characteristics of skewed bridges in Wenchuan earthquake is summarized and the influence factors of the deck rotation in the earthquake are studyed in this paper. And by using software Sap2000, a single-span and a 2-span simply-supported skewed bridge FEM model for time-history analysis are established. In the analysis,the main consideration factors with regard to the influence of seismic responses of skewed bridges are the collision between the deck and the abutment,and the horizontal support stiffness. The main conclusions obtained are as follows:â‘ For a regular single-span skewed bridges, with no consideration of the collision between the deck and the abutment, if the horizontal supports are symmetrical, there will be no deck rotation under seismic excitation.But if there are collisions between the deck and the abutment,the deck rotation becomes obvious.â‘¡The different horizontal support stiffness at different support can also lead to deck rotation of skewed bridges.The larger the difference between the height of piers and the stiffness of the bearing,the larger the deck rotation can occur during an earthquake.