When moment resisting steel frames (MRFs) are subjected to seismic load, high shears arise at joint panels. The effect of panel zone yielding resulting from these high shears may become significant for the seismic behavior of MRFs. In this paper, the elastic plastic behavior of joint panels in H shaped column to H beam connections are investigated conducting a series of loading tests varying its web thickness. Finally, a practical formula for predicting the restoring force characteristic of joint panels, which include H-H connections, SHS (square hollow section) -H connections and also CHS (circular hollow section ) -H conncetions, was proposed.
When moment resisting steel frames (MRFs) are subjected to seismic load, high shears arise at joint panels. The effect of panel zone yielding resulting from these high shears may become significant for the seismic behaviour of MRFs. In this paper, the elastic plastic behaviour of joint panels in rectangular hollow section (RHS) column to H beam connections are investigated by conducting a series of loading tests varying corner radius of joint panel (Test I) and manufacturing process of RHS column (Test II). From these test results and finite element analysis, a designformula for predicting plastic strength of joint panels in hollow section column to beam connections was proposed.
Large design loads are required for field splice of girder bridges with a thick and high-strength steel flange. A friction joint by high-strength bolts cannot be designed against such a case, because the capacity in usual size and arrangement of bolts is insufficient. This paper presents on the slip tests of high-strength bolted joints with filler plates inserted in the splice and base plates. Two kinds of filler plate used are low yield point steel and tungsten steel by thermal spray coating, which have different hardness. Test results of the relaxation in bolt tension force, the slip behavior of joints, the reduction of bolt force by loading and the slip resistance are discussed.
The full plastic and ultimate strength of connection were analyzed by assuming yield and ultimate mechanism respectively. The yield mechanism assumed can be classified as follows, yield mechanisms by moment yield lines in H flange(Y HF) and split-T flange(Y-TF), yield mechanism by the combination of moment yield line in split-T flange and bolt yielding(Y-TB), and yield mechanism by bolt yielding(Y-BB). The ultimate mechanism assumed can also be classified as follows, ultimate mechanisms by maximum moment lines in H flange(U-HB(a) and (b)) and split-T flange(U-TB) in connection with local ultimate state of connected bolts respectively, and ultimate mechanism by tensile strength of bolts(U-BB). The related experimental strengths of connections were analyzed by the presented strength equations showing appropriate coincidence, and the applicability of each yield and ultimate mechanism to the connection details is studied by numerical analysis of model connections.
Grinding the weld toe is the most popular method for improving the fatigue strength of fillet welded joints. Tool for grinding can be divided into two types; they are burr type grinder and disc type grinder. The disc type grinder is apt to make notches on the weld, and difficult to be applied to finish the weld toe due to its shape. However, disc type grinder is sometimes adopted in the actual treatments because it is easy to handle. This study is aiming at malting clear the influence of the grinding method on the fatigue strength of out-of-plane gusset welded joints through the fatigue tests and stress analyses.
A new type of moment frame is introduced in this paper The section of beams and columns are both the wide flange type. These are connected byknee braces with damping mechanism using high strength bolts. Knee brace dampers are specified to absorb the seismic energy effectively and to maintain beams and columns in elastic range. Seismic design method of the frame are presented and the dynamic responses of the frames against earthquakes are compared to the conventional rigid frame with rectangular hollow section columns.
This research is concerned with plastic deformation demand of energy absorption members in strong column type steel moment frames with eccentricity. And it proposes equivalent single mass and tri-degree of freedom systems based on energy conservation law. This paper confines to elastic response and discusses the validity of the systems according to comparison with earthquake response of the systems and that of space frame models using fishbone-shaped frames.
This paper presents results of a parametric analysis carried out on the mechanical characteristics and load carrying capacity of Nielsen-Lohse bridges subjected to lateral loads (wind loads). First of all, trial design is conducted for various practical bridge models subjected to lateral loads according to the Japanese Specifications for Highway Bridges (JSHB) in order to investigate the mechanical characteristics and load carrying capacity of these models. Second, the exact load carrying capacity of these models under lateral loads is numerically calculated through elasto-plastic and finite displacement analyses using a FEM program named EPASS. Finally, a rational and economical design method for the arch ribs of Nielsen-Lohse bridges is proposed based on the parametric analysis.
Nagisa-Bridge that was completed in last year is PC Cable-stayed and steel suspended combination bridge (DISCHINGER type suspension bridge). Combination Bridge is excellent in wind resistance and improvement of severe deflection, because stay cable system raises vertical stiffness of the whole bridge. This paper clear that Combination Bridge improved vertical stiffness of suspension bridge drastically in the geographical features which cable stayed bridge part of side span was fixed like Nagisa-Bridge. And the result of the vibration examination of Nagisa-Bridge and the analysis corresponded well.
The elasto-plastic dynamic buckling behavior of rigidly jointed single layer lattice domes under vertical and horizontal step wave has been analytically investigated in this paper. A step wave is a simple one whose response spectrum curve is horizontal line. Therefore, the buckling behavior of domes under dy namic loads can be easily grasped. From the numerical results, we have examined the time histories of responses, the dynamic buckling loads, the input energy and the strain energy and so on. Based on the above examinations, the effects of the half subtended angle of dome, input direction of step wave on the dynamic buckling behavior will be discussed.
Recently, the quality of steel has been remarkably improved, and high performance steel for bridge has also been developed. However, when it comes to how much, it has not been clarified. In this paper, first, we investigated the number of 1412 steel on the basis of the mill sheet in order to clarify their quality. Investigated items were tensile strength, yield strength, charpyabsorbed-energy, PcM(cracking parameter of material) and Ceq(carbon equivalent), and these steel mechanical properties were shown. Then, we also showed the degree of improvement in the quality, comparing with the data 30 years ago.