This paper proposes a method to evaluate the weld properties of steel structures without machining test specimens from the welds. Portable types of equipments were employed to examine the chemical composition, hardness and microstructure at the surface of the welds, assuming that minor surface polishing on the welds does not deteriorate the weld properties. The test results demonstrated that these methods can speculate the weld and base metal chemical compositions, welded joint strength and welding conditions applied. These proposed methods are thus effective for the field assurance of the weld properties of building constructions.
A practical method to examine the mechanical properties of a welded joint of actual building constructions is proposed. The Metallurgical characteristics of the joint (e.g., hardness), which are available by the seminondistructive methods proposed in the preceding paper, are used to evaluate the strength and the 0°C charpy absorbed energy. The method is also found to be successful in distinguishing hi-directional continuous welding condition from one whose interpass temperature is controlled less than 450°C.
This paper is intended as an investigation of the useful method of HAZ toughness evaluation and describes the results of toughness estimation for various structural steels for buildings, including JIS G 3136 SN steel. According to the experiment of fracture in the vicinity of beam-to-column connection, it often initiates near the root welding pass or finishing welding pass. Therefore, the new HAZ toughness evaluation method was proposed using one-bead welding to duplicate the coarse grain region, by taking notice of the grain-coarsened region in HAZ of the last welding pass. The HAZ toughness of SN steels and various high quality steels was estimated using one-bead method, and each exhibited the absorbed energy of more than 27J. Finally, it was examined to formulate the relationship between the HAZ toughness and the chemical compositions.
Distortional buckling may occur for cold-formed lipped C-section member subject to compression. In this paper, we carried out compression tests of cold-formed lipped C-section members with length where distortional buckling occurs in elastic buckling analysis and their buckling behavior is investigated. As the test results, local buckling of each component plate or flexural torsional buckling first occurred. For the lipped section which is fabricated according to the specification, lip/ flange junction deformed like distortional mode after web local buckling. In this tests, distortional buckling mode has little effect on the strength and the deformation behavior.
This study seeks to make clear the fundamental vibration behavior of rigidly jointed single layer latticed cylindrical roof structures having the constitutive members determined to be of an optimized cross-sectional area by using the reduced stiffness buckling concept. The present single layer latticed roofs are adopted as an equilateral triangle network pattern and pinned support system. A dynamic transient response analysis for damped up-and-down or horizontal motions is performed. The response behavior is shown to be much related to free vibration modes. The effects of the safety factor, the dead loading weight, the span and the cut-outs on the dynamic behaviors are discussed by using the result of a finite element analysis.
Presented in this paper are push-out test results on the ultimate strength of stud connectors buried in concrete which are restrained by flanges and a web of H shape steel members (Series-T) or by box shape steel members (Series-C). At first, four types of parameters, - (i) the degree of restraint, (ii) numbers and arrangements of studs, (iii) the strength of concrete, and (iv) existence of reinforced steel bars - are selected. The influence of these parameters on the ultimate strength is studied. At second, the estimation methods of the ultimate strength of stud connectors restrained by steel members are investigated. As a result, equations to calculate the ultimate strength of test results in Series-T, and C are proposed.
This paper deals with the shrinkage behavior in steel-concrete double composite continuous box girder bridge, which has two concrete slabs at upper and lower surfaces of the steel box girder in the region of the intermediate supports only. First of all, the relationship between stress and strain in concrete for analyzing the shrinkage behavior and the solution for shrinkage are presented. Next, a three spans continuous double composite box girder bridge is selected as the analytical model and its numerical analysis is carried out. Also, the test results used comparative large scale model are reported. Finally, the comparison between analytical and test results is presented and discussed herein.
Fatigue strength in three types of steel highway bridges including a two-plate-girder bridge and two kinds of four-plate-girder bridges were investigated by means of an equivalent fatigue design load approach . It became clear that the two-plate-girder bridge has the highest fatigue strength. In addition, the effect of transverse distribution of traffic flow on fatigue damage was examined.
In recent years, there has been disucussions about reducing cost and labor in bridge fabrication. There are some ways of reducing cost, automation is one of the ways . It recently has been further developed for bridge fabrication. In the case of girders of box-section, only the panels composing them are fabricated in assembly lines with robots. The automatic welding has, however, not been fully utilized for formation of box section, because it is difficult to manipulate the welding machines inside, their interior structures are complicated . Instead, manual welding has generally been used for this purpose, but welders are obliged to work under very adverse circumstances in this case. The authors proposed a method of using robots for welding in the interior of box-girders by which diaphragm and cross rib details are improved. In this paper, i mproving diaphragm details are discussed though stress analysis using finite element method