Wood used for exteriors, if left uncoated, experiences discoloration in the initial stage, and goes on to develop small checks on its surface. As exterior exposure progresses, the surface of the wood partially deteriorates due to weathering of the earlywood and latewood at the exposed surface and increased checking caused by differential shrinkage, resulting in an uneven wood surface. In this study, the process of surface erosion and chipping of wood and the inhibitory effect of various coatings were experimentally verified by outdoor exposure.
In this study, the required performance of the outer wall composite repair method using a transparent resin-based finish coating material for the tile-directed finished outer wall was examined based on tests. The required performance examined is shown below.
1. Adhesion between concrete frame and anchor pins
2. Adhesion of anchor pins to transparent resin-based finish coatings including tiles
3. Integration of direct-laid tiles and transparent resin-based finish coatings
4. Elongation of transparent resin-based finish coatings against out-of-plane deformation
5. Bonding of direct-laid tiles and transparent resin-based finish coatings when subjected to repeated hot and cold cycles (durability)
Generally, wind resistant designs of building components and cladding are developed using a static wind load based on the peak wind force coefficient. However, fluctuating wind forces repeatedly act on the components and cladding owing to the complex flow field formed around a building, and they may possibly lead to fatigue damage of the building. In this study, wind tunnel experiments were conducted on buildings with vertical fins to clarify the relationship between the wind forces and fatigue damage of the vertical fins; then, the fatigue damage was evaluated based on this relationship using the rain flow method.
In this study, the collision experiments to retaining wall with the base-isolated building model whose superstructure was designed to yield upon collision and the simulation analysis were conducted. The analysis captured the trend of the experimental acceleration response well, and the strains were comparable to the experimental results. In addition, the collision analyses were conducted on a full-scale base-isolated building with the parameters of superstructure strength and damping performance. As the superstructure strength was increased, the deformation of superstructure was smaller, but the acceleration was larger. On the other hand, as the damping performance was increased, both responses were smaller.
The purpose of this paper is to propose a two-step optimization method to design tuned inertial mass dampers for elastic-plastic MDOF structures using the time-frequency dual domain performance evaluation. Although the frequency-domain-based approach allows us to obtain the optimal design independent of the characteristics of disturbances, it cannot consider the elastic-plastic response of structures. On the other hand, the time-domain design is highly dependent on the characteristics of design earthquake ground motions. The proposed two-step method resolves these issues by use of dual-domain information. Finally, the response analysis for recorded ground motions demonstrates the effectiveness of the proposed design method.
It is known that when lead rubber bearings (LRB) are subjected to cyclic and large deformation under long period earthquake input, the temperature of lead plug rises up, resulting in deterioration of yield stress of LRB. The change in the response of the seismic isolation layer caused by the deterioration of yield stress is an important issue. This paper describes the earthquake response analysis method considering on heat-mechanics interaction behavior of LRB. Based on the study of response results and examination, the characteristics of the earthquake input are discussed. After that, a simple response evaluation method is proposed.
This paper proposes optimal design formulas and the optimal design method that can be applied to a multi-DOF system model of composite vibration control using MC-K type and M-CK type tuned dynamic mass system. We show the frequency dependence of the tuned dynamic mass system and clarify the mechanism for the damping imposition on uncontrolled modes. In addition, we construct the estimation method for the damping imposition on uncontrolled modes. Furthermore, we verify the effectiveness of modes control by vibration testing of a multi-DOF system model using the MC-K type and the M-CK type.
The increase of combination number according to the increase of variables is a serious problem in using section optimization for steel structures. Response Surface Method (RSM) which uses approximate functions made by sampling data was proofed as one of effective optimization methods. This paper shows features of the proposed method that combined with genetic algorithm by applying it to allowable stress design of a middle rise steel structure and changing the setting of RSM which are a response surface algorithm and a space filler algorithm. In addition, the feature of the optimized structures is analyzed by nonlinear dynamic response analysis.
The finite element technology assuming nodal coordinate is one of a useful method for form-finding of tensile structures, which does not require coordinates transformation and is described by a simple formulation. Furthermore, bending-active structures is known as a form-finding problem for hybrid tensile structures. It is possible to realize lightweight structures with self-equilibrium by the prestressing tension of the membrane and cables or the temporary external force during construction. In this paper, we drive the formulation of beam elements with the finite element technique assuming coordinate values, and apply the method to hybrid bending-active structures.
The purpose of this series of studies is to propose an assurance design method of connection in wooden wall structure calculated on allowable stress design and to verify its validity. In this paper, tensile, bending and combined load tests for the connection were conducted focusing on transition of uplifting condition, tensile load acting on each fastener and so on. From the test result, the point of deformation that column uplifting vanishes and each fastener’s tensile load could be appropriately predicted by the proposed calculation method. Furthermore, an already-known verification formula for combined stress was applied into the test results.
This study explores a seismic retrofit method for existing RC columns using a cast-in-site partial thick hybrid wing-wall (THW) technique. The THW technique plays two important roles: (1) to enable easy and cost-effective construction and (2) to considerably increase lateral strength and ductility. The aim of this study is to experimentally determine the shear resistance (truss and arch mechanism) and shear strength of the columns retrofitted using the THW technique. Based on the analytical assessment of the THW technique, design equations of ultimate shear strength and steel plate thickness are proposed.
Yield displacement is an important parameter in appropriately evaluating a seismic capacity of a building. To understand the detailed mechanics of flexural column deformation up to yielding of flexural rebar, deformation characteristics are measured with high resolution in a static loading test of five column specimens. Measured horizontal displacements are, then, separated into three displacement components, i.e., flexural displacement, shear displacement, and anchorage displacement, to find they are well simulated by classical flexural theory based on Bernoulli-Euler assumption, elastic shear theory considering uncracked horizontal section, and elastic deformation theory of stub considering flexural stress transferred from the column, respectively.
The long columns in atrium may often buckle by the non-sway mode due to the surrounding bracing frame. The objective of this study is to examine the effects of various factors on the effective length factor of the long column. Effective length factors are obtained by buckling slope deflection method, taking story height ratio, flexural stiffness ratio and axial load ratio as the parameters. The effects of these parameters are discussed from the view point of the effective length factor obtained from the G factor method and the restrain effects of the upper columns.
This study discusses connection strength of braces with various cross-sectional shapes. The monotonic tensile tests were carried out to investigate effects of connection detail on the connection strength. As a result, the ultimate strength basically increases in proportion to the number of bolts at the connection, regardless of the cross-sectional shape of the brace. Also, the ultimate strength of connection with more than 5 bolts does not increase compared to that of connection with 5 bolts. Finally, the equations of the ultimate strength for each cross-sectional shape are proposed.
The main purpose of this study is to develop fire resistant design based onreliability theory for a protected steel member at fully-developed compartment fire. The probability density function of the collapse temperature was approximated by using a shifted lognormal distribution. Novel fire resistance design using both steel member temperature and collapse temperature factors was proposed. Designers and engineers can design the mean value of the maximum steel member temperature, or that of the collapse temperature corresponding to the target reliability index.