This paper refers to the Nondestructive inspection method for compressive strength of cement mortar by using Pulsed electromagnetic force. We measure the Acoustic velocity of cement mortar by using Pulsed electromagnetic force and compared the Acoustic velocity of cement mortar with the compressive strength.
So the Acoustic velocity of cement mortar is faster when the compressive strength is higher. And the Acoustic velocity of cement mortar is faster when the water cement ratio is lower or the sand cement ratio is higher. As the result, the Acoustic velocity of cement mortar by using Pulsed electromagnetic force correlates with the compressive strength.

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In this study, influence of composite materials and mix proportions on the fresh properties and the mechanical ones of Hybrid Fiber Reinforced Cementitious Composites ( HFRCC ) was experimentally investigated. Then, the influence was analyzed by applying the excess paste thickness theory proposed by Kennedy in 1940 and formulated as functions of dominant factors. Results of the experiment and the analysis revealed the following matters:
1. The relative yield value and the relative plastic viscosity of HFRCC (yield value and plastic viscosity of HFRCC normalized by those of paste) decreased as the fiber volume content increased, and influenced by the geometry of contained steel fiber. Though it could not be quantified only by the excess paste thickness, the influence of sand-binder ratio, admixtures, volume content of each fiber and the geometry of the steel fiber on fresh properties and mechanical ones of HFRCC could be quantified by introducing modified excess paste thickness. However, it was not possible to apply it to express the influence of different water binder ratio.
2. The value of ductility index obtained by three point bending test increased as the fiber volume content and the aspect ratio of the steel fiber increased. By introducing modified excess paste thickness, the influence of sand binder ratio, water binder ratio, fiber volume content and aspect ratio of the steel fiber on the value of ductility index of HFRCC could be quantified. However, it was not possible to apply it to express the influence of different admixtures.

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This research aims at rationalization of the selecting technique of a crack repair method of construction with the movement occurred in RC structure. The definition of“existence of crack width behavior”of the flow chart in the public organization's specifications for crack repair method selection is so ambiguous. In this research, behavior of the crack produced in the outer wall of an actual building was measured, and new knowledge was able to be acquired about the opening-and-closing pattern and crack width behavior of cracks which were produced in the outer wall of building. Although it was generated in the building of only one building, and the cracks and consideration in this paper are based on this measurement results, it was thought that the results of this paper has the flexibility about the crack investigation for selection of a repair method of construction.

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Seismic base isolation is a very effective way of controlling the seismic responses of building structures. However, compared with conventional seismic systems, the robustness of the base-isolated buildings is generally considered lower and thus the selection of input ground motions becomes a more crucial issue in assessing the seismic safety of base-isolated buildings. Extensive incremental dynamic analysis (IDA) is carried out to evaluate the ultimate state of base isolated buildings in terms of the fragility curves. The ground motion record set in FEMA P695 is adopted for analysis. The influences of the stiffness of isolation layer, the height of rubber bearings, clearance and hysteretic behavior of the retaining walls as well as the strength of the superstructures are examined. Based on the analysis results, the following can be concluded:(1)increasing the clearance of retaining walls is the most effective manner to enhance the seismic safety of base isolated buildings; (2)the seismic safety margin of base-isolated buildings might be significantly increased with stronger superstructures only if the retaining wall is appropriately proportioned so that the yielding of retaining wall is prior to that of the superstructure.

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A new aseismatic reinforcement method for existing over-track station buildings has devised. In this method, we can reduce seismic response of the building to improve relative aseismatic performance using extension structures expanded in work for accessibility improvement carried out simultaneously. It can cut reinforcement work volume as well as reduce costs and construction time. In the model case,we evaluated aseismatic performance of the building of the applicable project by response analysis. The evaluation results demonstrated that coupling with an added vibration system that has dampers demonstrates remarkable response reduction effects.

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During the 1995 Hyogo-ken Nanbu earthquake, strong motions were recorded at two neighboring sites, Takatori (TKT) and Shin-Nagata (SNT), located in the western part of the damage belt in Kobe City. The latter, observed at the basement of a high-rise building, was less than half the amplitude recorded at TKT. This difference has gone unresolved in terms of the relationship between ground motion level and actual damage situation. This study investigate input earthquake motion to the high-rise SRC building at SNT during the 1995 Hyogo-ken Nanbu earthquake using three approaches: (1) a 3-D finite difference method to elucidate the spatial variation considering both the seismic fault and the 3-D basin-edge structure, (2) amplification characteristics using recorded motions after the 1995 Hyogo-ken Nanbu earthquake at SNT, and (3) the foundation input motion analysis, taking into account the strong nonlinearity of the surrounding surface soil.

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Changes in story stiffness and natural frequency of a high-rise building on the E-defense full-scale shaking test are experimentally evaluated from small excitations to the end of the ultimate shakes, which are expected to employ as damage index for structural health monitoring. Two kinds of changes are observed similarly from both shake test and ambient vibration, which occurred in the first seismic experiences by small excitations and after the severe damage when complete ruptures on main girders appeared in ultimate shakes. The latter severe changes in story stiffness are well-simulated by using a finite element analysis for seismic design.

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This paper proposes a time-history analysis model of high-hardness rubber that was recently developed for seismic vibration control of structures. The model combines elasto-plastic, visco-elastic, and nonlinear viscous constitutive rules. The rubber mechanical properties depend on frequency, temperature, and strain amplitude. The dependencies are effectively modeled through findings of their equivalencies. The nonlinearities under the idealized harmonic loading as well as random loading are carefully considered in the model. The model shows excellent accuracy over a wide range of temperature, frequency, and shear strains of a variety of histories.

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This study proposes to apply a structural reanalysis technique to an enumeration method for global optimization of discrete truss structures. The optimization problem is to find the sectional areas which minimize the truss structural volume from a list of standard sections under the stress and deflection constraints. At first, to reduce the computational effort, a structural reanalysis equation is derived, in which large number of unknown degrees of freedom are reduced. Next, a numerical generation method of relaxed linear constraints is also presented to reduce the number of structural analyses and re-analyses. The procedure of the enhanced enumeration method with above-mentioned two techniques is presented. The proposed method is applied to three trusses and compared with the structural analyses of all combinations.

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We, in this article, propose a manual calculation method of the embedment stiffness of partial compression parallel to the grain. The calculation method was derived from the mechanical model based on the mechanics. The embedment displacement was thought as the series system, surface of the timber at the bearing parts, and timber deformation. The timber deformation was modeled using the mechanics, assuming the stress diffusion angle was 18 degree. The validity of the proposed calculation method was confirmed by the experimental results whose parameters were the size effect, the length of timber, and the edge distance of timber. Using the average stiffness of the each condition, the calculation stiffness and experimental results were good coincident. And the size effect factor of the embedment strength of partial compression parallel to the grain was derived from the experimental results.

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The restoring force characteristics of embedment of wood are fundamental and very important to evaluate the seismic performances of traditional timber structures. In order to evaluate them effectively, elasto-plastic embedded displacements due to equally loaded rigid plate are formulated by applying Pasternak model to wood members with a finite length, taking the strain hardening and the orthotropic properties into account. In the formulation, the stiffness function is introduced to express the embedment stiffness simply in both elastic and plastic states. Then the formulations are discussed with embedment test results.

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Allowable shear strength for repair-control was specified in AIJ Standard for Structural Calculation of Reinforced Concrete Structures revised in 2010. However, this allowable strength was defined by limited data and past research indicated that in some specimens no shear crack was initiated at allowable strength.
The authors conduct anti-symmetric bending tests of R/C beams using SD295 to 785 N/mm² transverse reinforcement. It is confirmed that specimens with small transverse reinforcement ratio have frequently no shear crack at allowable strength. Finally, modified allowable shear strength accounting for transverse reinforcement ratio is proposed and verified to satisfy residual shear crack width limitation.

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Seismic response of the passive controlled structure using buckling-restrained braces (BRB) can be ensured when the BRB connection have sufficient strength. Therefore, it is necessary to prevent the occurrence of slippage or yielding at the connections. In this paper, parametric seismic response analysis was conducted to clarify main factors concerning strength of connections that will affect seismic response of structures. In the analysis, strength variations of BRB and bolted connection are considered. Finally, in order to ensure performance of passive controlled structures and decrease damage of frames, the methodology to determine the demand of strength for connections is revealed.

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In seismic design, moment resisting frame is designed to form the overall sway mechanism under severe earthquake. However, it is possible to form the weak column mechanism with the rise of strength of beams and panel zone due to strain hardening. The causes to collapse the weak column type frame are strong bi-axial seismic force, P-Δ effect and deterioration of restoring force. In this study, a series of response analyses of weak column type multi story steel frames under bi-axial ground motion are carried out. At first, using the elasto-perfectly-plastic hysteresis model, influence of the bi-axial ground motion and P-Δ effect on collapse behavior of frames are evaluated. Moreover, using the realistic hysteresis model including deteriorating range, collapse behavior and ultimate earthquake resistance of frames governed by deterioration of columns are evaluated.

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To clarify the bolt bearing effect to the ultimate strength of the high-strength bolt connections, two series of testing, bolted connection applied with tension force or bending moment, were conducted in this study. From the test results, design formula, considering the bearing deformation explicitly, was proposed to evaluate the ultimate tension strength of the high-strength bolt connection; the improved accuracy compared with current design formula was also shown. Extending the proposed design formula to the bolted connection applied with bending moment, improved accuracy to predict the maximum bending strength was also shown; however, it was also reminded some refinement still needed to improve the accuracy.

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This study deals with the structural behavior of concrete-filled oval tubular (CFT) steel columns. The design formulae are proposed approximately on the yield bending moment and full plastic moment of the oval CFT cross section. They are available in the arbitrary loading direction by introducing simple power series of trigonometric function instead of the difficult elliptic integral of the 2nd kind. Experimentally, specimens were tested under reverse-symmetry cyclic loading to investigate the effects of the loading direction of the oval, axial force ratio, and deformation capacity of the CFT columns. The test results verify that these effects depend on the curvatures around the compressive edge of the oval tube sections. Based on the experimentally obtained equivalent diameter - to - thickness ratio (D/t) of elliptic tube, simple evaluation formulae are proposed on the confinement effect and deformation capacity of the oval CFT columns.

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Typical steel moment-frame structures in the United States comprise a few seismic frames and many gravity frames, which include “continuous columns” that are pin-connected to beams. These continuous columns, which are often ignored in seismic design, can improve the seismic performance of the structure. This study investigates the effects of continuous columns on the structural stability and seismic response of building frames. Stability coefficients representing the separate and combined effects of geometric and material nonlinearities are used with a simplified modeling technique, which separates the shear-type and flexural-type lateral-force-resisting systems in moment frames. Relationships between continuous column stiffness ratio and the stability coefficients, inter-story drift, and the drift concentration factor are presented. It is shown that for realistic structures, the columns in the seismic frames are generally sufficient to prevent unstable response and large drift concentrations, and the inclusion of gravity continuous column stiffness tends to decrease both the drift concentration and inter-story drift.

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