Various cope holes are employed in Japanese highway bridges. The shape and size of the cope hole, however, depend on the authority if the hole is applied to the same. In this paper, reasonable shape and size of the cope hole according to a structual details has been discussed in taking account of bridge fabrication process, its efficiency and fatigue strength. Especially, diaphragm details are discussed though stress analysis using finite element method. Finally, how to select cope hole details is proposed.

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The AIJ "Recommendations for the Design and Fabrication of Tubular Structures in Steel" specifies that the effective length lk of a compression chord for the out-of-plane buckling of a steel tubular truss could be shorter than the distance between the lateral supports, since the compression chord is laterally stiffened by the tension chord and the web members. In terms of increasing the buckling strength of the truss, it might be economical to enlarge the cross section of the compression chord only. However, the effective length of the chord should be somewhat longer than lk, so that the tension chord, which section must become relatively small, would lose a bit of the stiffening effect for the compression chord. The paper will present the method to evaluate the effective length of the compression chord for that.

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An experimental study of the behavior of concrete filled steel tube columns and results of an elasto-plastic analysis are presented. Eighteen columns with square sections were tested under concentric or eccentric loading. Effects of key parameters such as buckling length-section width ratio, LkJD, and eccentricity of the applied axial load were studied. The test results correlate well with both the results of the elastoplastic analysis and Recommendations for Design and Construction of CFT Structures.

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Regarding the circular-section steel bridge pier (steel pipe column) designed by the seismic coefficient method, a quasi-static cyclic loading test and a pseudo-dynamic test using reduced-scale test specimens of the same details were conducted . And using the pseudo-dynamic test results as the comparison, the effectiveness of the seismic resistance capacity evaluation method was investigated, based on the information obtained from a cyclic loading test . The investigation results show that the dynamic analysis results using the restoring force model (two-parameter model) obtained from the hysteresis loop of the cyclic loading test agree well with the results of the pseudo-dynamic test . On the other hand, it was confirmed that the seismic resistance capacity based on property of energy conservation using the hysteresis loop envelope curve results in underestimation

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We have taken up in this study the negative effect of the secular change where the phosphate treatment is applied in the frictional surface treatment of the hot dip galvanizined friction joints. We have carried out a relaxation test of the friction joints and slip test thereof after exposure as a method of investigation. As a result of it, it has turned out that the phosphate treatment shows the higher performance with relaxation less than the blast treatment and without any major negative effect during the slip test after exposure. therefore, we wish to make a report of it here.

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Maintenance work for steel structures is essential to sustain their long lives. Some damages to steel member, such as thickness decreasing or perforating, bring deterioration of their ultimate strengths and shortening of their lifetime. However, a damage criterion for the steel member is still indistinct. Therefore, it becomes important how to evaluate the strength of damaged members. This paper presents a buckling test and finite element analysis of cylindrical tubular members with man-made thickness decreasing or perforating, which are looked on as a damaged member, and characteristics of their ultimate strengths. Results of numerical analysis made influences of the thickness decreasing or perforating on the ultimate strength deterioration clear quantitatively.

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The hollow ball joints, which consists of a hollow ball, high strength bolts, cones, washers and tube members, have been developed to construct space roof trusses. Six specimens comprising of a hollow ball, bolts and washers were tested under various combined loads. The ball diameter and thickness are 200mm and 27mm, respectively, and the bolt diameter is 36mm. The primary objective of study is to investigate the relationships between the ball deformation, the force required to pull the bolt out of the ball, and the ultimate strength of the bolts.

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Longitudinal bending deformation and angular distortion were influenced by the welding sequence. Its magnitude was the smallest in the case when welding was continuously performed from one side to the other side. But, angular distortion was different for left and right sides. Longitudinal bending deformation was not so greatly influenced by changing of the welding speed or the heat input. However, angular distortion was largely influenced. When the heat input exceeded the certain value, angular distortion conversely became small. Residual stress?D? (component of welding line direction) became large when the welding speed became fast or the heat input became large.

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In the design of the steel bridge piers in Japan, it is requested to check their restoring lateral strength against the strong earthquakes specified by the Japanese Specifications for Highway Bridges. The restoring lateral strength of steel bridge piers is mainly governed by the strength of the weakest ones of their column members, pier bases consisting of the anchor bolts, footings and foundations. It is necessary to define the ultimate limit states and formulate the inelastic behavior of these structural components for precisely calculating the restoring lateral strength. In this paper is, therefore, defined the ultimate limit states and formulated the inelastic behavior of steel pier bases subjected to cyclic bending moment keeping axial compression constant by using a pier base model idealized as a RC structure.

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