Recently, bonding patch plate is used for rehabilitation of steel structures deteriorated with corrosion or fatigue cracks. The patch plate tends to decreases the stress intensity factor at crack tip and delay the crack propagation. However, debonding of patch plates could occur around the end of patch plates and at fatigue crack edges. To evaluate debonding of patch plates bonded to the cracked steel plate, axial loading tests for butted steel joint with bonded patch plates were conducted. Furthermore, the shear and normal stresses in adhesive layer were analyzed. The debonding strength of the joint was evaluated from a view of principal stress in adhesive layer.
In this paper, various design codes for lateral bracings are compared about beam strength, plastic deformation capacity, out-of-plane deformation and stiffening force. Maximum beam strength showed full plastic moment and the strength was maintained until beam end rotation angle 0.045 rad. Plastic deformation capacity R showed three or more. Out-of-plane deformation was almost within 150mm. However, stiffening force was large in long beam. In design code, required stiffening force is 2 to 3% of compression force of flange, but maximum stiffening force was 9%.
The knock-off type steel side block, proposed by the authors, provides a displacement restraint against a small earthquake but has some technical problems to be solved for a wider application of it. In this study, an improved design equation on breaking load of the side block is proposed by referring to its failure mechanism. Also dynamic behavior of isolation bearings having the side block are grasped through shaking table test and seismic responses of viaduct with the bearings having the side blocks in the transverse direction of the bridge axis are investigated through seismic response analyses.
Tsunami flotsam attacked many steel buildings in the 2011 off the Pacific coast of Tohoku Earthquake. Steel buildings construct popularly by using tubular columns. One of the difficulties to evaluate the strength of steel tubular member against the collision of Tsunami flotsam is local deformation caused by the collision, which degrades the overall strength. Furthermore, contact surface shape of collision object, for example, sharp or flat introduces variation of local deformation and the corresponding strength reduction. The filling concrete into tubular members (CFT) would be alternative to overcome the disadvantages. Therefore, we performed static FEM analysis by using the program MSC Marc. The collision by Tsunami flotsam categorizes as the low velocity collision, so that the static analysis may be applicable to investigate the above topics. We discuss that the overall strength degradation by local deformation and the effect of loading tip shapes for vacant steel tubular members and CFT members.
In this paper, a new type damping wall system using torsional steel tube damper is proposed. This proposed system has a feature that we can set the stiffness and yielding strength freely. And we can set any opening for doors or windows where designers want. For the proposed system has stable hysteretic energy absorption, it is important that steel tube damper shows stable hysteresis. But it is known that with large radios-thickness ratio, steel tube damper has small energy absorption ability. So, in this paper, the critical radios-thickness ratio of torsional steel tube damper for large energy absorption is confirmed by FE analysis.
Stress concentration factor of in-plane welded gusset joints with circular transitions is examined analytically. The focus is on the influence of the geometry, which is defined by parameters such as the flange width D, the transition radius r and the gusset plate length L. Parameter study results show that the effect of D and r are significant, but the effects become less and less with increasing D. Based on the results, a stress concentration factor equation is proposed for covering larger D. The proposed equation has better agreement with FEM results compared to the conventional equation, when D becomes large.
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