Investigation On Energy Dissipation And Accumulative Damage Of Welded Beam-to-Column Connection Under Earthquake Cyclic Loading

Postgraduate: LI JIE, the Degree of Master of Engineering was awarded in March 1999 at Tianjin UniversityDue to its lightweight, good earthquake resistant performance, high degree of the industrialization and high speed of installation the steel structure is widely used in the industrial fields. However, in the recent earthquake of Northridge in America and Kobe in Japan, brittle fracture occurred in the beam-to-column connection, which is relevant to the factors of welding. So, it is very important to direct the research of improving the earthquake resistant behavior for steel structure. There are two different type of cyclic loading: horizontal and vertical cyclic load in this paper. The FEM analysis of three type of widely used connection (H-H, H-B, B-B) is performed in and the response of every type of connection is computed under different loading mode. The energy dissipative coefficient is presented in the paper and the energy dissipative coefficient of three type of connection is obtained. The results indicated that the earthquake resistant performance is better thanthat of the other two types connection. In the condition of not varying the basic parameters the effect of different shape factor of weld on damage and the effect of strength match for 16Mn is directed in this paper.The dynamic fracture toughness research under seismic loading of the 16Mn and Q235B structural steel is directed in this paper. The dynamic and static toughness of welds and base metal under room temperature is performed. The loading rate is 100mm/s, 50mm/s and 0.1mm/s. The COD of welds and base metal under different conditions is obtained. The test results indicated that: with the increase of loading rate the CTOD of the 16Mn steel base metal and welds is increased, however, with the increase of the loading rate, the CTOD of the Q235B steel base metal and welds is decreased. It can be concluded that the dynamic loading is disadvantage to the Q235B steel. So, it is evident that the earthquake resistant performance of Q235B is poor.