The Theory And Test On Constant Amplitude Fatigue Behavior Of Grid Structure With Steel-Pipe-Welded Hollow Spherical Joints

The Grid structure is a set of higher statical spatial structure, as a factory prefabrication, site assembly, suitable for industrial production structure, due to its advantages of beautiful appearance, reasonable force, making simply, and wide application. In recent years it develops rapidly in China. In the suspension crane under the action of welded hollow spherical joints grid in the domestic is more and more widely application , but the global engineers begin to think about it which the fatigue problem of suspension crane . The Fatigue test is a method known to explain joint or component fatigue feature in engineer field, it has the advantages of direct and dependable. However, due to the fatigue test is a long,expensive and uncertain research, the fatigue test advances slowly at home and abroad.This article as one of the topics of National Natural Science Foundation , relying on the National Natural Science Foundation of China (50678109) for financial assistance, based on the function which constant amplitude fatigue of grid structure with steel-pipe—welded hollow spherical joints as the target, start the following works, and get some usefull result.1,To set up a effective,stable and reliable test device, through this device can better finish all the works of the fatigue test. 2,To set up and design the tool which used the test of steel-pipe—welded hollow spherical joints, and produced for fatigue test of hollow sphere, the test tools have a good quality and precision.3,To analyze the stress of steel-pipe—welded hollow spherical joints.4,Based on the fatigue test, get 15 datas which the test of steel-pipe—welded hollow spherical joints. make the full and systemic analysis, get the S-N curve of joints.5,To analyze the fatigue feature of fracture and the uncertain function which effect the fatigue test datas.6,To make the method which design the fatigue strength.This research results for setting the method of grid structure design and construction method provides some usefull results.