Welding conditions are important factors for performing good welding. In this study, the effects of thermal histories on the strength of weld metal is presumed by experiment and the heat conduc tion analysis by the finite element method. The relation between the thermal history near the fillet weld and the strength of a weld metal is obtained by experiment. And strength of weld metal is presumed from the cooling speed in heat conduction analysis. As a result, it was good correlation that cooling speed near the welding part in heat conduction analysis and ultimate strength in weld metal in the range of this experiment.
Fatigue crack propagation life prediction using linear elastic fracture mechanics is usually based on the assumption that applied stress is perpendicular to initial cracks. Therefore, its application for combined normal and shear stresses is somewhat limited. In this study, fatigue crack propagation life prediction of weld joints under the combined stresses is discussed. Based on the concept of the strain energy release rate, the modified Paris' equation expressed by equivalent stress intensity factor is proposed. Fatigue crack propagation lives of butt welded joints containing an inclined lack-of-penetration and non-load-carrying fillet welded joints with inclined ribs are calculated, and they are compared with the test results.
The results of slip tests on high strength bolted joints with high slip coefficient are described in this paper. The parameters of these tests are the surface treatments of main connected plates, the pitch and direction of cutting wave shape on splice plates, the number of specimen bolts which fastened the plates, the diameter and strength of specimen bolts and so on. And the influences of these parameters on the slip characteristics are considered.
The authors have been studied the buckling behaviour of axially compressed tubes with through-gusset connections. In order to obtain the buckling strength of the concentric system with the double shear connections, the precise analysis and the simple formula were proposed, and their accuracy was confirmed by the loading tests. But for the eccentric system with the single shear connections, only the precise analysis was established, and its accuracy was confirmed by the loading tests. In this analysis, the iterative calculation is necessary to obtain the buckling strength. This paper deals with the simple estimate of the buckling strength for the eccentric system for the sake of practical design. Through the use of simple mechanical models and the application of some simplifications, the buckling strength can be given as a root of the quadratic equation.
In the current Japanese Specifications for Highway Bridges (JSHB), the design methods for bridge members made of high strength steel are not specified. The design of such members is, therefore, carried out by using the ultimate strength curve similar to that of mild steel members, and the ultimate strength curve is not verified for the members made of high strength steel. In this study, the ultimate strength of beam-columns made of high strength steel designed by the ultimate interaction curve of JSHB is investigated through a parametric study based on elasto-plastic and finite displacement analyses considering the inherent characteristics of residual stress distribution and stress-strain relationship of high strength steel. It is concluded that the ultimate interaction curve of JSHB can be used for the design of beam-columns made of high strength steel but it is a little bit conservative.
This paper presents the results of loading tests regarding RBS moment connection with staggered hole alignment developed for use in rehabilitation and upgrading of existing non ductile moment frames. Major findings obtained from loading tests are as follows: 1) fractures initiated from the toe of a weld access hole is prevented; 2) method to evaluate the flexural strength of RBS with staggered hole alignment on the bottom flange are suggested and its varidity is confirmed.
In this researdh, the tensile experiment to focus on the behavior of the wrapping wire and the berKbng experiment to focus on the influenoe which the wraaping tension exerts on the behavior of the parallel wire cable are conducted The specimens used are three parallel wire cables constituted of PWS253 is 5.0mm in dian filler wires, and low carbon steel wire as the wrapping wire. The specimens were wrappad by wrapping tension of 0.29, 0.4, and 0.57kN respectively. The cable tension was set to obtain the sane geonelric stiffness as the main cable in the actual suspension bridges The following results are obtained from this study. The bending stiffness of the vvrapped parallel wire able is controlled by the cable tension, warpping tension, and the bending angle of the cable. Moreover, the secondary stress of the wrapped parallel wine cable is by sliding between the wires.
This paper describes the structural characteristics of an Open-Grating slab as bridge deck. The slab consists of two layers, namely upper surface slab to be used as pavement and lower structural slab. First, 3D-FEM analyses were done to find stress concentration phenomena at the vicinity of connection between main (longitudinal) member and cross (transverse) one in the lower slab. Second, multi-point static loading tests were carried out to know stress variation within those members under a wheel tracking loading. Last, fixed point-cyclic loading tests were carried out to find fatigue strength of the lower structural slab. From the numerical and test results obtained, main discussion was made on fatigue characteristics of the open-grating slab applicable to a bridge deck.
Partially encased composite steel I-girder with steel bars welded to the flanges has been proposed and studied by experiments and analyses. The partially encased girder had 2.08 times higher' bending strength and 2.98 times higher shear strength than the conventional steel I-girder. When the steel bars were not welded to the flanges, the bending strength was less than the encased girder with welded steel bars but still 1.75 times higher than the steel I-girder. When the deformed I-girder was filled with concrete, the bending strength was improved with I.89 times of the steel I-girder. The analytical methods have been proposed to assess the bending and shear strength and the calculations agreed well with the experimental results..
This paper presents an alternative loading test to verify load-carrying capacities on concrete filled tubular columns in multi-columns composite bridge piers. The elasto-plastic analysis was carried out by using the fiber model. As a result, the load-carrying capacity and fracture process of the proposed multi-columns composite pier was made clear. In addition the validity of the elasto-plastic analysis using fiber model was proved by comparison with experimental results.
Structural deformation control under earthquakes has been conducted recently by connecting steel shear walls or steel wall-type dampers with steel frames. The steel shear walls or steel wall-type dampers provided with proper rib-plates exhibit high ultimate strength and plenty of plastic deformations following shear buckling of the walls. We analyze numerically elastic-plastic behaviors of the steel shear walls and steel wall-type dampers using the FEM program. In the analyses, 400Mpa-grade and 100Mpa-grade steels are adopted, and various divisions by the rib-plates for the walls are considered. From the analytical results, we propose a design formula for obtaining the required rigidity of the rib-plates to ensure that the steel shear walls and steel wall-type dampers would have enough elastic stiffness and ultimate strength according to their materials
In this paper the spatial distributions of earthquake motions on shallow alluvial valleys with an irregularity in soil layer composition are first checked. Based on the results of analysis, the seismic responses of a large-span gable structure are calculated considering the input difference at the footings due to spatial distributions of the motions. The results of calculation show that the different acceleration inputs will excite an additional vibration associated especially with the second natural symmetric mode as well as the first natural anti-symmetric mode. Furthermore, a method for calculating the seismic responses to the structures is proposed to consider the different inputs based on the results of present paper.