Autoclaved lightweight aerated concrete (ALC) panels are utilized as exterior walls due to their lightweight and good insulation properties, especially in Japan. In the ALC panels, the mounting hardware plays a crucial role in connecting the ALC panels with the foundation or structural components and providing resistance to wind and earthquake loads. Thus, the strength of connections is a critical factor in determining the overall stability and safety of the ALC panels. However, there is a lack of studies on the connections. Considering this research gap, an experimental study was conducted to investigate the mechanical behavior of connection in ALC panels.
This paper proposes a method for finding the optimum damper placement which connect two buildings to reduce the seismic response of building structures. The proposed algorithm is simple iterative procedure to add small amount of damper into most effective story incrementally. The effectiveness of connecting damper is evaluated from maximum response in time range or the maximum value of transfer function. The validity of the proposed method is examined through numerical examples using multi-mass shear model considering maximum response in time and frequency range. Furthermore, the comparisons of solutions using multi-mass shear model and reduced one storied model have been conducted.
Several semi-active control laws were proposed to reduce the maximum response of the benchmark test model of the base-isolation system, and their effectiveness was verified through E-Defense experiments.
1. Control performance and response reduction effects of testing control laws could be appropriately evaluated considering the equivalent damping factor for each semi-active controlled response.
2. Proposed semi-active control laws could be classified as two typical types depending on their force-velocity characteristics.
3. Proposed semi-active control laws could reduce the maximum displacement responses without increasing the absolute acceleration of the superstructure, while the control performance depended on the seismic motion characteristics.
Building window glass is brittle and susceptible to damage due to impact loads; therefore, studying the fracture behavior of window glass under impact is significant in protecting human safety. This study focuses on experimental and FEM simulation of window glass fracture by the low-speed heavy weight’s impact. The fracture behavior of the window glass was observed in the experimental tests. Using the FEM model, reasonable material parameter values to reproduce the fracture behavior of window glass are investigated through sensitivity analysis. The simulation results are compared with the experimental results, and the validity of the numerical model is confirmed.
In this paper, a new method is proposed that replaces the ground motion with multiple impulses in a rational method by considering the repetition characteristics of the ground motion, and a method to set the input level of impulse ground motion in consideration of robustness. In addition, for an example problem of optimizing the placement of inter-story dampers in a multi-mass point system model, it is shown that the use of impulse ground motions provides a design solution that is more robust against variations in the phase characteristics of ground motions than optimization that uses only specific ground motions.
The vertical bearing capacity of piles by embedment method is considered to be affected by the strength and stiffness of the grouted pile base, but there are few reports on this subject. Therefore, various experiments were conducted to understand the effects of differences in the quality of the grouted pile base on the bearing capacity. As a result, it was found that sand and gravel does not significantly affect the bearing capacity even if they are mixed in the grouted pile base, but clay and block of clay decreases if they are mixed more than a certain amount.
This paper focuses on roof structures consisting of radially arranged cables with a radial arrangement of cables between the inner tension ring and the outer compression ring. Although many examples of the adoption of this structure have been reported outside Japan, no actual examples have yet been reported in Japan. Therefore, the authors are conducting this study with the aim of preparing structural design documents with a view to adopt this structure in Japan. In this paper, a method for calculating the equivalent static wind load for evaluating this structure by static analysis is proposed and its applicability is discussed.
Although AIJ recommendation for design of latticed shell roof structures has suggested a procedure to calculate buckling capacity of cylindrical latticed shells, calculation methods of the buckling capacity for the shells subjected to non-uniform load remain to be one of the indefinite issues. This paper investigates the effects of both load eccentricity and geometrical initial imperfection on buckling loads of cylindrical latticed shells with a special focus on the variation of the knock down factor due to the load eccentricity, and the results provide improvement for the estimation procedure suggested in the current AIJ recommendation.
This paper proposes a prestress-jointed wooden semi-rigid frame with wood/steel hybrid braces. First, an overview of the frame is given. Next, mechanical models of the braces, the column-beam joints, and the columns and braces joints are presented. Finally, static push-over analysis and earthquake response analysis are performed on one frame of the study building using the analytical model of the frame with the mechanical model in place. Equivalent damping constants, maximum response values, and energy absorption about four types of wooden semi-rigid frame structures are compared, and their seismic resistance is evaluated.
To investigate bending characteristic of the plastic hinge of steel bar-timber composite column under lower to higher levels of axial force, compression test and cyclic bending test of column were conducted, and it was revealed that compressive stiffness, and compressive strength of the hinge were greatly increased by steel bars, and moment-rotation angle relationship of the hinge from low to high axial force and its correlation curve between axial force and bending strength were clarified. Furthermore, the correlation curve and the cyclic moment-angle relationship could be estimated accurately by the plasticity theory and the calculation method for reinforced concrete.
This paper describes the simplification of reinforcement in RC soft-first-story column-beam joints with mechanically anchored column longitudinal rebar. The main objective was to reduce the complexity of reinforcement in the joint by anchoring column and beam main bars in a straight manner. Two types of reinforcement arrangements were proposed to particularly prevent anchorage failure of the beam top reinforcement and verified their effectiveness through static loading tests. The test results showed that both specimens behaved in ductile manners without brittle failure of the mechanically anchored column and beam longitudinal rebar.
In this study, damage control for precast concrete beams post-tensioned by unbonded tendons at widened beam ends were investigated through loading tests and numerical analysis. The use of steel-fiber reinforced concrete reduced the damage during post-tensioning. The use of indented PC steel strands suppressed damage at drift angles of more than 3%. Based on the experimental results, the limit state was judged, and it was found that most of the limit states were determined by the concrete. The numerical analysis model using the fiber model could trace the hysteretic loop and the drift angle at limit state with good accuracy.
This paper presents prediction methods of maximum strength around strong axis of local buckling H-Shaped beams connected by flush end plates. This paper studies the neutral axis position of the beam section around the connection and consider that the neutral axis position moves towards the compression region due to out-of-plane plastic deformation of the flush end plate. The influence of the movement of the neutral axis position for maximum local buckling strength is estimated by the energy method and accuracy of the estimation is checked by the experiment of the full-scale specimen and the nonlinear FEM analysis.
A new type of one-sided fastening system using weld nuts with flange is proposed and experimentally investigated to examine its practical feasibility especially in terms of pretension control. The weld nut is designed to show a special performance such that the incorporated flange undergoes elastic deformation, then plastic flow and finally contact on the seating plate during the tightening process. These sequential behaviors are confirmed experimentally, which indicates that the pretension greater than the plastic flow load can be introduced into the bolt. In addition, an analytical method to calculate the flow load is presented and ascertained.