In Hokkaido, clearing snow from roofs results in a large number of accidents involving people, every time there is a heavy snowfall. The numbers have not decreased since the heavy snowfall of Heisei 18 (2006), suggesting that the promotion of countermeasures initiated against accidents at the time has been ineffective. In this study, the authors investigated conditions of snow removal around Iwamizawa City where heavy snowfall occurred in 2012. In addition, we tried to plot fragility curves for accidents involving people in Hokkaido, and analyzed the effectiveness of measures against snow damage. In the investigation, it was found that some individuals had climbed onto roofs in order to clear snow overflowing from flat roofs designed to prevent snow from sliding off. Furthermore, the heavier the snowfall, the higher the incidence of dangerous attempts at snow clearance. Following the investigation, the performance of 14 regions in Hokkaido in tackling snow damage was analyzed based on fragility curves for accidents involving people. As a result, it became clear that increases in the number of accidents each year were heavily influenced by not only the frequency of snow clearance and depth of snow but also the percentage of elderly in the population.

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The present paper discusses the characteristics of wind forces acting on the external wall binders of a high-rise building based on the results of a wind tunnel experiment from the viewpoint of fatigue damage. Special attention is paid to the binders connecting the external curtain walls and the structural frames. A wind force direction conversion factor for the relation between wind force and member stress is introduced into the fatigue evaluation together with the normalization of stresses. Furthermore, a discussion is also made of the influence of mean stress on the fatigue damage, which depends on the wind direction and speed.

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On the sedimentary basin, the characteristics of ground motion varies with incident angle and azimuth angle of the seismic wave due to the complicated soil structure. Especially, the predominant period of the seismic ground motion, which is very important in the design of high-rise buildings, often varies with the direction of the hypocenter. In this study, we focus the effect of sedimentary basin structure on dynamic characteristics of seismic ground motion, using the three dimensional finite difference method and the reciprocity theorem of Green's function. We study especially focusing effect and trapping effect of seismic waves. We also discuss the fluctuation of predominant period for the seismic design of high-rise buildings.

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We construct a new method for reasonable evaluation of seismic bedrock spectra using borehole records observed at KiK-net sites. In detail, the method first reduces the observed spectra at borehole stations to seismic bedrock spectra, and then derives corner frequency and Q-value characterizing the source and path effects from the reduced spectra. We validated the applicability of the proposed method using records obtained in Kinki area. The results show that derived Q-value and stress drops calculated from derived corner frequencies are more stable and accurate than the conventional methods.

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The paper presents a method to evaluate optimal viscous damping ratios and cumulative ductility factors of a structure with bilinear hysteretic dampers and dynamic mass dampers, subjected to an arbitrary earthquake ground motion. It is the principle of the proposed method that the total energy of the structure with arbitrarily specified ductility factors is constructed by summing the modal energies when the modal deformations are agreed to the modal ductility factors computed through the corresponding eigenvalue analysis. The numerical examples show the procedure has high accuracy in estimating cumulative ductility factors as well as the maximum response values.

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Rocking behavior can affect the performance curve of structure derived by structural monitoring with accelerometers. The performance curve may show nonlinear behavior if rocking behavior shows nonlinearity due to lift-up. In order to investigate a method to eliminate rocking effect from derived performance curve, a series of shaking table test with three-story steel frame with rocking device was conducted. The test results showed that rocking behavior can be measured by accelerometers and the effect can be eliminated from the measured performance curve.

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Although large numbers of attempts have been made to evaluate buckling strength of cylindrical lattice shell roofs under equally-distributed vertical loads, stability under seismic loads has not been studied enough yet. In this paper, evaluation method on buckling strength of cylindrical lattice shell roofs based on continuum shell analogy under equivalent static seismic loads proposed in the previous studies is investigated. First, the buckling behavior under distributed loads proportional to the static seismic loads is researched taking shape parameters into account. Next, the buckling strength for vertical loads and the buckling strength for static seismic loads is evaluated using continuum shell analogy, and converted to elasto-plastic buckling strength using knockdown factors and Dunkerley formulation. The effectiveness of the proposed evaluation is discussed against the results of time-history response analyses.

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In the 2011 Tohoku Earthquake, a large number of school gymnasia suffered damage and were unable to be used as shelters. One of the most typical damage observed in steel roof gymnasia supported by RC frame were failures at the anchored connections of steel roof bearings on RC frames. In the previous paper, we have discussed on the response of cantilevered RC walls supporting steel roofs using analytical model of a damaged gymnasium in the 2011 Tohoku earthquake, and the obtained analytical results were evaluated on the observed damage. In this paper, the action of cantilevered RC walls supporting steel roofs is investigated using parametric analysis model of various school gymnasia. Based on the analytical results, a simple response evaluation method for the cantilevered frames and reaction forces at roof bearings are proposed.

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In this paper, the results of experiments on the shear strength of the dovetail joints which were machined have been reported. Relationship of shear strength properties and shape has been studied by three tests. In addition, on the basis of the failure type, it was also considered embedment strength .In conclusion, the shear strength of dovetail joints, among the shear strength of Ogi and the shear strength of Megi and the embedment strength, be determined by the lowest strength was revealed.

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We have developed a new shear-key using a steel disk and an anchor bolt in order to use in joints of seismic retrofitting. It was already obvious that the shear-key had higher shear strength and stiffness than post-installed anchors. Outside-frame method is one of seismic retrofitting methods. In this method, joints are subjected to not only shear stress but tensile stress through expanded slabs. In this study, we investigated the potential uses of this shear-key to expanded slab. Test specimens had the proposed shear-keys to resist shear stress and adhesive post-installed anchors to resist tensile stress. As a result of the test, the shear-keys also afforded higher shear strength and stiffness under these conditions. Moreover, we constructed the design method for applying the shear-key to expanded slab, and it was obvious that horizontal capacity of expanded slab with the shear-keys could be reasonably estimated by the proposed shear strength formula.

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The performance of passively-controlled building depends not only on damper but also on frame members and connections. Frame members are subjected to bending moment and shear force caused by the story drift and relatively large axial force caused by the damper force. The axial force can cause earlier yielding and possibly local buckling in the elements, but very limited studies are available on this problem. In addition, because the detailing method of the connection elements such as a gusset plate and stiffeners has not been established, there are a variety of designs including many that are irrational and inadequate. This paper intends to develop a design and analysis method to alleviate such problems. Full-scale test method is developed as an efficient approach and tests are conducted on 10 subassemblies consisting of beam, column, and gusset plate, and the results are analyzed and discussed.

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From the economical point of view, H-shaped beams which have end stiffeners have been designed in steel frame structures. The purpose of this paper is to reveal the elastic buckling strength of stiffened plates under bending and shear stress. Theoretical analyses using energy method are conducted. As prerequisite for the buckling analysis, web plate element is supposed in consideration characteristic of stiffener. From the analysis, the effect of the stiffeners to the elastic buckling characteristics is inspected and the approximation for optimum rigidity is derived for each boundary condition. In addition, the effective shape of stiffener elements is also investigated with theoretical analyses.

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Mechanical properties, residual stresses and dimensional accuracies of large-size structural steel tubes of circular hollow section designated as STK400 and STKN490B were investigated. The sample number was 18 as delivered, and half cuts of them were normalized. As-delivered tubes exhibited higher yield strength, tensile strength and yield ratio, but less uniform elongation than their correspondent normalized ones. Charpy absorbed energy of as-delivered was smaller in circumferential direction than in longitudinal direction, the tendency of which was not altered in the normalized. Residual stresses in ERW tubes in their longitudinal direction were extremely large in comparison with UO-forming tubes and Bending-roll tubes. Dimensional deviations from nominal sizes were small enough to satisfy the JIS tolerances, but not always met European Standards.

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The fire resistance of high-strength (120N/mm²) slender RC columns is evaluated by conducting experiments and also by finite-element analysis. Experimental parameters are the ratio of column height to cross-section diameter and the axial loading of the specimens, while the results obtained are fire resistance time and failure mode. A proposed finite-element method of evaluating critical buckling strength based on tangent-modulus theory is then applied to the columns. In a parametric study using this method, the results indicate that the amount of transient strain and main reinforcement strength have little influence on buckling strength.

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Projectiles would be released by an accident such as damage of turbine blades, and impinge on structures. Flying objects such as airplanes are also possible to be impact projectiles. These accidents occasionally cause fire, if there are fire load such as oil, fuel and any other combustible materials. This research focuses on the structural fire behavior of load bearing reinforced concrete walls exposed to fire after high velocity impact of a hard projectile. Impact and fire experiments on small scale reinforced concrete walls were carried out. The results show the influence of local damage and the advantage of short fiber reinforced concrete against fire.

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