A 5-story building was demolished owing to the large number of fractures suffered in its beam-column-connections during the Hanshin-Awaji Earthquake. Investigation results of this seismic damage will provide very important teaching material for evaluating existing connection forms. Seismically damaged beam flanges are examined, and analyzed to determine their fracture modes and their tensile, absorbed energy and hardness properties. The heat effects on steel adjacent to repair welding are also examined. This paper describes observations of the initial crack growth leading to brittle failure. It also investigates the material properties of the base metal and compares them with those of the degenerated area and those weld heat-affected zones.

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The 1995 Hyogoken-Nanbu Earthquake attacked Kobe on January 17, 1995 and brought us the huge destruction. At the IKUTA shrine, a lot of buildings were damaged and the Hall of Worship fell down completely. In the ruins, the superior priest of the shrine requested us to restore the buildings as soon as possible to encourage citizens of Kobe. Then reconstruction of the shrine started on January 22, 1995. The progressive technology to give the buildings sufficient seismic resistant capability is intended. For the columns of the new Hall of Worship, CFT(Concrete Filled steel Tube) is used, and the concrete which compressive strength is 160 NJmm², is filled into the tube. The reconstruction procedure of the new Hall will be reported herein.

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The allowable stress criteria is more frequently governing the design than the ultimate limit state criteria in most of steel frames. In this paper, steel frames with rectangular hollow section columns and wide flange beams are designed based on the following rules. Beams are proportioned so that maximum stresses just reach allowable stresses. Columns are proportioned to fulfill the story drift limitation and to keep maximum stresses within allowable stresses. The ultimate strength of these frames is then discussed. The results obtained from this study are summarized as follows: (1) Members in upper stories are relatively stronger than those in lower stories. (2) Frames tend to be of weak beam type structures. (3) When a sway mechanism fomns in a story, the collapse load corresponds to a D_S -value of 0.32 or greater,

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The cylindrical tubular steel members are widely used as the column members in the steel structures. There are lots of studies on the buckling strength of steel tubular column and the design formulas are proposed. But there are few studies onthe perforated members or the tubular column with variable thickness. It is possible to occur the deterioration of strength owing to the decreasing of cross-section, the stress concentration around hole and the interactive behavior of both. In this report, the buckling strength of the perforated cylindrical tubular column is tested and the influence of the hole on the deterioration of buckling strength is studied.

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In AIJ (Architectural Institute of Japan) design formula for slender composite columns, modified method of the superposed strength of a column section is adopted by considering the effect of additional bending moment (Pδ moment) . In this paper, with respect to the ultimate strength of concrete filled steel tubular columns, end moment (cMu)-axial force(cNu) interaction relations are calculated by assuming a sine curve deflected shape of a concrete beam-column. The value of concrete compressive strength ranges from 240kg/cm² to 960kg/cm². On the basis of the analytical results, the interaction relations are proposed as an algebraic equation. Moreover, example for calculating the end moment-axial force relations is demonstrated.

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To investgate the failure charactristics of beam-to-column welded joints and the plastic deformation capacity of steel beam caused by scallops, a monotonic loading and cyclic loading one were carried out for full scale models which were cantilever beams. The present paper describes an outline of these tests and discussions on the ovserved test results. While the previous tests for reduced steel beams showed that the type of the scallop had an effect on the deformation capacity of the steel beam ^[6]-[11], the present test for full scale beams did not disclose that the plastic deformability would be governed by the type of scallop.

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In order to acquire the knowledge required in an expert system for preliminary design of cable-stayed bridge, a database regarding to 137 cable-stayed bridges which are now under service and erection has been constructed. Then, an attempt has been made to develop its expert system, into which the information and knowledge obtained from the constructed database and the existing resear ches related to the cable-stayed bridges are incorporated. If only total length and width of the bridge are input into this system, then the appropriate types of cable system, pylon and main girder are suggested. And the rough total steel weight, axial force of pylon, non-linear bending moment of main girder, critical wind speed for flutter, etc. are indicated. A schematic perspective of the suggested cable- stayed bridge can be also shown on a display if the user requests it.

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