In welded steel structures, the fatigue failure sometimes occurs at the weld joints. The present maintenance is done by the watching of workpeople and the detection of the minute damage is very difficult. This study has investigated the way of detecting fatigue damages in some welded structural components. The examined structural components are beam-pillar joint test components and bead welding specimens. As a result, it has been confirmed that fatigue damages, which occur from the weld toe, can be detected with the monitoring of strain change near the weld toe.
This study aims at examining the fatigue strength of fatigue cracked out-of-plane gusset welded joints repaired by the stop-hole or the bolting-stop-hole method. For this purpose, following examinations have been performed. They are fatigue tests on as-welded joints and the joints repaired by the stop-hole or the bolting-stop-hole method, stress measuring tests and stress analyses using three-dimensional finite element method in consideration of plate thickness, hole diameter and crack length. On the basis of the results, the evaluation formula for the fatigue strength has been proposed, and validity of the formula is verified by comparing the predicted results with the experimental ones.
There are many researches about the structual behavior of electric resistance welded tube, but few researches about that of spiral steel pipe, which is mainly used for steel pipe pile. The deformation capacity of the member is improved by preventing local buckling of wall elements because welded part of spiral steel pipe is spiral and the seam welded part is thicker than wall elements of steel pipe. In this study, local buckling behavior of spiral steel pipe is clarified by stub column test of these kinds of pipes. We investigate the local buckling strength and deformation capacity of spiral steel pipe by previous experimental formula for electric resistance welded tube inthis paper.
Structural behaviors of concrete-filled square tubular steel column to steel H-beam connection with T-shaped inner reinforcement, which were intended to simplify the steel fabricating of connection and concrete-filling into the steel column, were studied by cruciform tensile test and beam-and-column subassemblage test subjected to earthquake loading. Stable and ductile hysteresis characteristics were obtained in the subassemblage test. The ultimate and Full plastic strengths of the connections were estimated approximately by applying the yield line theory considering the simple stress transfer mechanism of the connection.
The new truss system is introduced that comprises pipes, joint bolts and steel nodes. The unique feature of this system is that the mechanism for tightening the joint bolts is housed inside a sleeve, Six pipe-to-node connection specimens with different pipe diameters and node materials are axially and biaxially cyclically loaded. A unit truss specimen is loaded and an elastic analysis is carried out. The test and analytical results indicate that the initial stiffness, taking into account both pipe stiffness and joint bolt stiffness, are in good accordance. Additionally, the bending rigidity of the pipe-to-node connection is clarified by a bending test.
The present work proposes a knock down factor which can be used in esti mating elasto-plastic buckling loads as well as in proportioning members of reticulated domes based on consideration of shall-like buckling. In the first part, a discussion is made on how the knock down factor is derived based on an analysis of shell-like buckling of reticulated domes using past, various elasto-plastic buckling results covering vast geometries and boundary conditions . In the second part, several domes designed based on the analysis are verified to satisfy the required ultimate loads required in design stage.