This paper proposes a new stud-type damper using steel shear panels. This damper is available for both newly constructed steel buildings and existing steel buildings. In this paper, a simplified model for static or dynamic response analysis is proposed. This model is composed of two elasto-plastic rotational spring and elastic member which deforms axially. The test results clearly reveal that the hysteresis loops of the specimens are stable up to 0.02 rad and that the shear panels have enough plastic deformation performance. It is also verified that the stiffness, strength and amount of shear deformation of the damper can be predicted very well by the presented mechanical model.
This paper presents a construction experiment of a stud-type damper using shear panels and a loading test of a fullscale steel frame reinforced by the damper. First, ways of connecting the damper to existing beams or concrete slab are proposed. Secondly, the construction experiment and the loading test were conducted. Test results are summarized as follows ; (1) the damper was placed on the steel frame without any difficulty, (2) the hysteresis loops of the specimen were stable up to the loading cycle of 0.02 rad and the specimen formed collapse mechanism as expected, (3) connections between the damper and beams did not collapse through the loading test. Finally, it is verified that the stiffness and yield strength of the damper can be predicted very well by the presented mechanical model.
New beam-to-column connection is proposed for large elasticity to prevent damage under large eartquake and for reuse in the future. This connection can be made by employing super-high-strength steel (SHSS) with yield points of 800N/mm2 and super-high-tension bolt (SHTB) with split tee joiner. To verify its structural behavior, tensile and cruciform type beam-to-column connection specimens were tested and analyzed with an FEM. Tests and analytical results confirmed that the connection method is feasible as new reusable structures keeping elastic under large earthquake. However, the increase of strength for split tee and beam-to-column connection panel is still needed for further improvement.
Fatigue tests have been carried out on specimens with welded attachments under plate bending, such as lifting lug and stud dowels. Fatigue crack growth behavior of each type of specimen has been observed by dye and beach marking techniques. The test results show that fatigue crack initiates at weld toe and propagates to about 80% of plate thickness before failure. The fatigue test data under plate bending test are compared with the previous test results. The fatigue strength for bending is also evaluated by using one-millimeter stress method.
As for the maintenance of steel bridges, evaluation for deterioration and damage caused by corrosion is important. The authors suggested that fatigue strength of corroded steel plate could be arranged by maximum stress range considering stress concentration due to corrosion surface geometry. However, factors controlling stress concentration and expression for stress concentration could not be obtained. This study aims at proposing fatigue strength evaluation method for corroded steel plates though close observation on corroded steel plate surface, fatigue tests and elastic three dimensional finite element stress analyses.
We propose a method using high-strength steel stud columns for seismic retrofit of existing high-rise steel buildings to prevent excessive residual deformations. The essential requirement of the present method is that the post-yield story stiffness including the P-Δ effect be positive. The present method requires strengthening members much less than conventional retrofit methods. We demonstrate in numerical examples that the use of 800 to 1000MPa class high-strength steel allows the stud columns to be elastic even when interstory drift ratio is 0.02. It is also shown that the present method is effective to prevent the occurrence of excessive residual deformations under long-period ground motions caused by a subduction earthquake.