In recent years, it has been some discussions about reducing cost and labor in bridge fabrication. As the way of reducing this cost, automatic welding or high efficiency welding will be increasingly used Automation has recently extensively developed in many factories, however, it is only few case using high efficiency welding. For this reason. Specifications for Highway Bridge regulates limited heat input considering embrittlement and softening (maximum heat input is 70KJ/cm on SM570). The authors investigated charpy absorbed energy on the basis of many technical reports by using high heat input welding in order to examine the effect of embrittlement. In this paper, it is investigated Vickes hardness and tensile strength to examine the effect of softening. From the results of their investigations, the authors propose limited heat input considering both embrittlement and softening.
A load-carrying capacity curve of cruciform column high Mn projection panel (Mn panel) assembled by structural steels and high Mn steel was obtained. In elastic buckling, the ultimate strength of Mn panel assembled by dissimilar steels was nearly equal to that of Mn panel assembled by similar steels. However, in elastic-plastic buckling, both of the ultimate strengths were different. Whichever similar steels or dissimilar steels might be assembled, the stress-displacement behavior of each projection panel was same as that of steel itself, when the existed steel structures were repaired or reinforced, the use of the steels whose strength is higher than that of the present steel makes the ultimate strength of the existed structures higher.
New connection detail of steel girder embedded in reinforced concrete abutments using perfobond ribs is experimentally studied to verify the load carrying capacity of integral bridge connection between steel girder and RC abutment. The static loading tests of steel girder-RC abutment connection detail are carried out by changing the parameter of perfobond ribs and the length of embedded girder section. As a result, the contribution of perfobond ribs in the moment resisting connection is verified and the resisting moment capacity of this connection is discussed.
By narrowing box girder width, it is expected that overall costs will effectively be reduced. Moreover, by increasing slab thickness, it is possible to omit stringers in accordance with decreasing the box girder width. Thus, box girder's fabrication productivity and bridge durability are greatly improved. The purpose of this paper is to show the aforementioned bridge type to be versatile for future designing activities.
Dealt with in this paper a method for deciding the proper shape of initialdeformation for elasto-plastic and finite displacement analysis of rigid framed steel bridge structures through using a Nielsen-Lohse bridge model as an example. In themethod, an elasto-plastic buckling mode in the vicinity of the ultimate limit state, which can be approximately obtained without executing eigenvalue analysis, is adoptedas the proper initial deformation shape. Proposed in this paper also is a method for finding out structural members of which strength affects predominantly the loadcarrying capacity of steel bridge structures by comparing with the results of elastoplastic and finite displacement analysis of two models. One is the model idealized withelasto-plastic finite elements, and the other one is the model in which the structuralmembers under consideration are idealized with elasto-plastic finite elements and theother members are idealized with elastic finite elements. Effectiveness of the method isverified by using two numerical models of cable-stayed bridges.
The strength efficiency of the welded beam web joint between rectangular hollow section column and wide flange section beam is influenced by the out-of-plane behavior of the column flange connected. The experimental and analytical research works were carried out to investigate the design formula of the flexural strength of the welded beam web joint. The flexural strengths estimated from the equality hypothesis of plastic virtual work proposed by authors and the upper bound theorem proposed by Suita and Tanaka, both assuming the same yield line mechanism are discussed in this study. From the results of finite element analysis on the elastic-plastic flexural behaviors of the model joints, the flexural strength proposed by authors agrees well with the general yield strength of the joint, which can also be applicable to estimate the plastic strength in the wide range of plastic deformation of the beam-to-column connection.
Recently, a visco-elastic damper (VED) has been applied to multistory buildings to reduce the responses of structures under strong earthquakes. However, there is few study for the application of the VEDs to space frame structures. The purpose of this study is to show the effectiveness of the VEDs installed in a gable truss structure under severe earthquakes. Earthquake response analyses are carried out with varied parameters;(1) the position of the VEDs, (2) the size of the VEDs, (3) the magnitude of peak acceleration of earthquakes. The results based on the numerical studies have confirmed that the VEDs effectively suppress the earthquake responses of the gabled truss structures.