This paper presents experimental and numerical studies on the effects of undermatched welds with very low Si and Mn welding wires using GMAW process on 490N/mm2 class steels. Undermatched welds prevent cold cracking without preheating. The results of CTOD and fatigue tests of welded joints shows that the strength of welds influenced the characteristics of fracture toughness and fatigue strength. The results indicates lower strength of welds provided higher fracture toughness and fatigue life (Nf).

View full abstract

This study focuses on the development of a new method of H-shaped beam-tosquare tube column connection. Two specific types of beam-to-column connection are proposed; one is the type of connection using vertical stiffener with shop welding and the other is external stiffener with field welding type. The structural behavior of the cross-shaped frame with these con nections is examined experimentally by eight test specimens under cyclic loading. The test configu rations, test procedure, and specimen details are given. Next, analytical strength of beam-to-column connection for the each specimen is given and experimental beam-end loads versus rotation curves are discussed. From the results, it makes clear that vertical stiffener and external stiffener type connections proposed in this paper, are reliable connection methods.

View full abstract

The structural behavior of the new moment resisting connection system, in which the stress continuity plates at beam flange levels are discarded, and the wall thickness of SHS column is increased at panel zone, was investigated against horizontal loading using the full scale test subassemblages. For comparison, the same size subassemblages with the conventional connection system (through diaphragm system) were also tested. It was found out that the load carrying capacity of the subassemblage increased substantially compared with that of conventional assemble system. This advantage was brought by the increase of shear resistance of panel zone.

View full abstract

We have investigated the slipping characteristics of the hot dip galvanized high strength bolted friction joints with a phosphate treatment, on which a cyclic loading is imposed repeatedly by earthquakes and so on. As a consequence of a series of our experiments, the phosphate treatment has indicated a characteristic more excellent than the blast processing. While the blast treatment makes slipping load increase with the help of pressure, the phosphate treatment has proved favorable without such a phenomenon as seen in the blast counter-parts.

View full abstract

A new type of beam-to column connection is presented in this paper. The section of beams and columns are both the wide flange type. These are connected by the joint elements with damping mechanism using high strength bolts. Trianglar and belt-shaped joint elements are combined to absorb the seismic energy effectively, and to maintain beams and columns in elastic range. The test results indicate that the connections have sufficient performance.

View full abstract

Experimental study was carried out to examine the effectiveness of arrangement of reinforcement in a footing beam for an exposed-type steel column base. In the study, location of horizontal anchor and amount of vertical reinforcement are selected as experimental parameters to investigate suitable arrangement of reinforcement. In the tests, a column base is loaded through a column subjected to horizontal and vertical loads at the top. Test results show that the ccolumn base reinforced by horizontal anchors, which are placed at the upper side of anchor plates, and by a few amount of vertical reinforcement does perform as well as that fully reinforced by vertical reinforcement.

View full abstract

This paper proposes a method to approximate the out-of-plane effective bucklimg length for web members of circular tubular trusses with unstiffened branch joints. Using a nonlinear buckling analysis, the effective length is determined for a number of tubular trusses with various dimensions. Based on the numerical results, the effective length is represented by a simple formula. Comparisons with the numerical results proves the very high accuracy of the proposed formula for buckling loads.

View full abstract

Various prestressing methods are considered to prevent the undesirable crack of concrete slab in steel-concrete continuous composite girder. When the studs for shear connection between concrete slab and steel girder are welded in the form of group, we can introduce the prestress effectively only into the concrete slab by using the internal prestressing tendons. However, mechanical characteristics of the composite girder with grouped studs are not clarified perfectly. In this paper, therefore, an analytical treatment and the calculated results of composite girder with grouped studs are reported and discussed.

View full abstract

In this paper, mechanical characteristics of steel bellows as energy absorbing bridge connecters are investigated. Steel bellows are connected between girders in a row or between girders and abutments in order to reduce the damage of steel girders. First, the desired performance of steel bellows is arranged. The loading tests were carried out to examine characteristics of steel bellows and their results are compared with calculated results by FEM. Design formulas concerning the yield strength and yield displacement of steel bellows are developed based on the principle of virtual work. The values obtained by the design formulas are compared with calculated values by FEM. Geometrical dimensions of the steel bellows are changed, and the influence which dimensions of steel bellows exert on initial rigidities, yield loads, yield displacements and the maximum strength are evaluated by using FEM and the design equations.

View full abstract

Multi-support excitation analysis for an existing suspension bridge (Ohnaruto Bridge) was carried out applying the actually recorded accelerations of Hyogoken-nanbu earthquake (1995) on each foundation. The analyzed results were compared with the actually recorded response of the superstructure, and the analyzed results of uniform excitation analysis. The results of multi-support excitation analysis reproduced the better approximation for the first vertical bending mode deformation than the results of uniform excitation analysis.

View full abstract

This monument was completed in March 2000. It was erected to commemorate the opening of Shimizu Port 100 years ago. A simple design was required which could become a durable and easily recognizable landmark. A form derived from reference to a Japanese legend "Hagoromo" was used. Three curved, twisted triangular prisms are arranged in a tripod configuration, joined at 12m above ground level. The overall height is 20m. Aluminium production and fabrication has been one of the principal local industries in Shimizu for many years. For this reason it was decided to make the monument in aluminium. Each prism comprises aluminium plates formed by pressing and welding into triangular planes. The use of triangles allows the resulting surfaces to follow the complex geometry of each prism. Plate thicknesses vary from 10 to 20mm. Since aluminium did not have general approval for use as a structural material in Japan, at the time a special application was required to the Building Center. In order to verify the stability of the frame and confirm the stresses in each plate a detailed finite element analysis was performed. The analysis considered complex typhoon load on each prism from various directions.

View full abstract