Experimental Research On Seismic Behavior Of H-beam Space Steel Truss Joint

The water-cooled technique of air-cooled condenser, used in large heat power plants, is a new water-cooled technique. The air-cooled condenser structure system is the main support systems for the air-cooled condenser. Its substructure is large reinforced concrete pipe column, and its superstructure is space steel truss. It supports heavy equipment loads and complex dynamic loads. It is a vertical steel reinforced concrete mixed structure, which has complex connection and is upper flexible and lower rigid. Today, many air-cooled condenser structure systems are still designed by developed countries. There are not any full and systemic design method and rules about the air-cooled condenser structure system in our country. It can be a help for the engineering design to deeply analyze the structure behavior and have an examination research on the typical joints and members in the air-cooled condenser structure system.In this paper, the seismic behavior of a typical joint in the air-cooled condenser structure system is researched.As is so difficult to simulate the fact suffer load circumstances of the space steel truss joint, the joint specimen is designed as a space steel truss cell. According to the pseudo static test of a typical space steel truss cell, the mostly destroy mode of the specimen are summarized, the hysteretic behavior of the specimen is analyzed, the calculate mode of the air-cooled condenser structure system and the original design methods about the joint are pointed out in this paper.The main brittleness breakages of the specimen are the welded seam rips between the level inclined brace and the chord and the connect damages, where the space between of the bolt hole is not satisfied with the design request and the force is larger. The main half ductile breakages of the specimen are the enlargement of the bolt hole in the joint. The ductile breakages of the specimen are high strength bolt slippage, the plate rip in the bolt connect place, the level inclined brace is compressed buckled, the diagonal web is compressed buckled and the joint plate is buckled.The bearing capacity of the space steel truss cell is well, and the deformation capacity and the ductility is quite well. The deformation of the joint region is small, and its rigidity and bearing capacity are quite well. The energy dissipation of the truss structure is mostly relatedwith the chord deformation.Taking into account of the importance of engineering structure and the designing principle of strong joint, when the checking computation of anti-seismic is being done on the joint, its anti-seismic adjusting factor of bearing capacity Y0re is suggested 1.0. Allowing for the complex dynamic load on this structural system, the bolt connection of joints should be adopted with high-intensity friction-type bolts and the friction surfaces can be dealt with sand blasting. And the welding connecting of them are advised to use slope butt weld that are fully welded, but when the double-sided fillet weld is used, they should be design on equal strength. The bolt connection between the member and the joint should be designed on equal strength and meet the structural demand. And the specified suggestions about the constructions and the calculate methods of the joints are pointed out in this paper.