In our previous study, shear-bending loading tests were carried out in order to estimate the bending-shear behavior of shear-yield-precedence short-span beams. The results demonstrated that the short-span beams have good structural behavior. This paper describes simulation analyses of representative specimens using FEM. A method for evaluating maximum shear strength is proposed and verified using test and analytical results. The method takes into account the diagonal tension field. When the width-thickness ratio and the shape ratio of the beam web are appropriately designed, the short-span beam is proved to have sufficient deformation capacity.
In recent, much damage has been detected in superannuated bridges. Especially, the fatigue problems of aged steel bridges become serious in the maintenance of the bridges. Recently, the serious and large crack of approximately 1.1m length was detected. In the web plate of interior main girder at the intersection of the main girder and the transverse girder, and at the location near the interior support in the center span of a three-span continuous girder bridge. If such a large crack occurs, the load carrying system of bridge should be changed and its capacity will be decreased. Accordingly, it is important to evaluate the load residual carrying capacity of damaged bridges with a large crack from the viewpoint of the management of the bridge system. The objective of this study is to investigate analytically change of the load carrying system of the various damaged three-span continuous girder bridges with four main girders.
In out-of-plane gusset welded joint, fatigue cracks usually initiate from the boxing weld toe in which high stress concentration exists. The fatigue strength can be improved by making smooth shape of boxing weld toe. Grinding process is a popular method for finishing weld toe. This process can remove weld imperfections and create a smooth transition between weld and base plate. But fatigue crack initiation points sometimes move to weld roots. This research is aiming at making clear the reason of root failure through fatigue tests and FEM stress analyses. On the basis of the results, the method to prevent root failure has been proposed.
Strength and slip factor of high strength bolted friction joints were obtained through loading tests. Specimens were assembled from weathering steel base members and blasted splicing members. Weathering steel plates were cut out from lower flange plate of a bridge that was exposed for 8 years in open inland field, and it has been generated protective rust on its surface. Base members were treated in some levels of rust removing. Applied treatments are blasting, disk sanding, powered wire brushing, manual wire brushing and cloth wiping. Protective rust decreases the slip factor, and thin crystalloid rust increases it, but thick rust over 100μm decreases it.
In this study, the steel fabrication cost functions for the building frames consisting of box columns and H beams are first shown. These cost functions are applied to two structural design cases A and B of three example buildings. The structures of design case A are consisting of beams of the same depth in X and Y directions and columns of the same depth in the vertical direction. The structures of design case B are designed to make total weight small. Each sum of the material cost and the fabrication cost of these structures is calculated, and the difference of total cost for these cases is discussed.
Local stress behavior around welded joint between angle-shape shear connector and bottom plate in steel-concrete composite slab was investigated by 3D FEA. From the analytical result, local bending deformation was observed when the bond between concrete and steel plate was lost. Also, it was confirmed that local stress around welded joint due to local bending deformation was strongly correlated with shear stress of shear connector. After these analytical investigations, correlation equation between stress concentration factor of welded joint and shear stress of angle shape shear connector was established in order to carry out fatigue design. Moreover, in this paper calculating methods of bending moment and shear stress for steel-concrete composite slab using angle shape shear connector were recommended.
To observe ultimate state of steel and concrete composite slab, static load experiment was carried out for test models that were cut down a part of steel and concrete composite slab. As a result, it was recognized that starting point of concrete crack is top of steel rib. On this paper, it is proposed that nonlinear FEM analysis applied to steel and concrete composite slab needs to include material and boundary nonlinear characteristics. By results of comparing this experiment with proposed analysis way, the analysis could create concrete frist crack confirmed in this experiment. And, application limit of the analysis is turned out.
A new type of shear friction damper was proposed as an energy-absorption device. The new device can applies two levels of shear resistance just by controlling the bolts tension force in two sides of the damper. The side where the lower bolts tension is applied can absorb the seismic energy by a moderate earthquake, the other side where the higher bolts tension is applied can absorb the seismic energy by strong earthquake respectively. In order to investigate and clarify the characteristics of the new damper, a total of three dynamic loading tests were conducted. Experimental results have indicated that the damper can absorb seismic energy effectively in both levels of shear resistance, and an analysis model of the damper was also proposed.
This paper presents the applicability of CFRP adhesion for the repair of corroded steel members. In this paper, the peeling behavior of CFRP was investigated experimentally in tensile and flexural tests of steel member with CFRP adhered. As a result, the influence of the design parameters such as, “number of CFRP layers”, “bonded length” and “surface treatment” on the peeling strength was clarified. Based on these experimental results, the design method how to determine the required volume and bonding length of CFRP, and how to check the peeling of CFRP from steel and so on are given.