The use of clay walls on bamboo lathing less burdens on the environment, but it is necessary to confirm their properties in order to use this wall construction method more widely in safety. In this paper, fracture behaviors were observed, including full section sized specimen and element specimen which were loaded force. As a result of full section sized experiments, four types of behaviors as load-bearing elements could be found. As a result of element experiments, when all four types of elements bearing the load compare with one element, the initial stiffness improved, but the toughness decreased because of the delamination at the interface of layers were markedly happen.

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This paper presents results of full-scale loading test of rocking type precast concrete curtain walls subjected to large in-plane story drift over 0.2 rad. From test results, the method to estimate the rotation of a panel and the deformation of joints are proposed. The failure of curtain walls occurred at the bearing support of a panel and the collision between panels led the failure of the panel at the corner and some pieces of broken concrete has fallen. The method to predict the collision of panels are also proposed and the validity of the method is verified by test results.

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This paper proposes tsunami fragility curves for low- and medium- rise RC building considering collapse modes, such as overturning and sliding, based on the examination of the database of damaged buildings during the 2011 off the Pacific coast of Tohoku Earthquake. Log normal distribution is assumed for fragility curves, and the median and logarithmic standard deviation are estimated. One of difficulties for mode-based fragility estimation is that it is impossible to identify the most contributing collapse mode beforehand. The maximum likelihood method using multi-nominal likelihood function (Nakamura & Ugata, 2009) is extended, so that no assumption is needed about the relationship between each collapse mode. Proposed fragility curves include statistical uncertainty considering limited number of damaged buildings in the database.

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This paper shows fundamental properties of the damper authors have been developed with the aim of vibration control of building structures. The damper developed by authors uses both the mass effect by rotary inertia and the variable damping effect by magnetorheological fluid. In this paper, authors make a 100kN type test model of the damper developed, and experiment to bring out its performances with vibration tests by sine wave input, etc. In sine wave tests, the negative spring property by inertia mass and significant energy absorption by MR fluid are confirmed. Authors also confirm the validity of theories and analytical method on knowledge from performance test. And authors intend to carry out practical realization of rotary inertia mass damper using MR fluid.

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Earthquake motions have directivity occasionally on near site of fault rupture. That causes severe damage to structure. The effect of this directivity of earthquake motions on structural damages is estimated by two models. One model named Bi-directional coupling model is created on the basis of an analogy to the plastic theory. So, using thies models, it is possible to estimate Bi-directional plastic response of structure to earthquake motions. Another model named Bi-directional decoupling model is simple composition of Bi-directional response of 1-directional model. The defference between plastic strain energy measured by these two models, and the method to estimate the response of Bi-directional coupling model using Bi-directional decoupling model considering directivity effect of earthquake motions are shown on this paper.

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The functions to estimate overturning ratios of furniture in residential buildings are developed using indoor damage data during the 1995 Hyogo-ken Nambu Earthquake and results of analytical studies for overturning of rigid bodies. The functions are verified to match the indoor damage of tall buildings in Tokyo during the 2011 Off the Pacific Coast of Tohoku Earthquake. By using these functions, indoor damage in tall residential buildings in Tokyo is estimated during Nankai Trough earthquake and a large inland earthquake. The situation of indoor damage might be different depend on characteristic of seismic motions and buildings.

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Performance of three pile foundations then under construction thus without superstructures during the 2011 Tohoku Pacific earthquake was examined on the basis of field investigation including inclinometer and camera survey as well as of numerical analysis. It is shown that: (1) a single and a 2x2 group pile foundations were vitally damaged at a depth of about 10 m, the bottom of the liquefied layer, and displaced horizontally by about 10-60cm, whereas the other large group pile foundation did not suffer any damage; (2) the largest bending curvature in the two damaged pile foundations occurred at a depth of about 10 m, suggesting that the pile damage was probably caused by cyclic ground displacement of the liquefied sand; and (3) the difference in pile moment capacity as well as pile head connection might have differentiated the performance of the three pile foundations during the earthquake.

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At 2011 Tohoku Earthquake, many school gymnasia suffered damages owing to not only Tsunami but the consequent shake. One of the most typical damages observed in steel roof gymnasia supported by RC frame are failures at the anchored connections of Steel roof bearings to RC frames. Such failures were observed in not only aged structure but recently designed gymnasia, which mean that further guideline is strongly required. However, evaluation of reaction forces at these connections is not easy because of complicated response characteristics between steel roofs and cantilevered concrete walls. In this paper, the action of cantilevered RC walls supporting steel roofs is researched using analytical model of actual damaged gymnasium in 2011 earthquake. The obtained analytical results are evaluated on the observed damages, and response characteristics of cantilevered RC walls are discussed, followed by proposal of easy design methods for these connections.

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Details of connections are developed for steel-timber hybrid structural members, which are economical and take advantage of the beneficial properties of each material, such as the strength of steel and ease of construction of wood. In a hybrid member, a steel plate is sandwiched with timber on both sides. The steel and timber are connected with high-strength bolts, which penetrate through doubly placed steel pipes. The outer pipe, which is slightly (1mm) longer than the inner pipe, is designed to buckle under compression when the bolt is tightened. The outer pipe expands radially as it deforms inelastically and fills the gap in the timber hole, thereby enhancing the initial bearing stiffness of the connection. The inner pipe prevents the outer pipe from shortening more than 1mm. The bearing performance of the connections was investigated experimentally and analytically.

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In this paper, evaluation method of "collapse limit displacement" of RC buildings based on seismic response spectrum was proposed. The method is more practical approach to evaluate collapse limit displacement than previous method based on dynamic analysis. Collapse limit displacement estimated by the method was compared with dynamic analysis of simulated and observed ground motion in past. The results showed good agreement with dynamic analysis. However, cases that natural period of model equal to 0.2sec showed large dispersion. In addition, it was clarified that capacity degradation curve affects to collapse limit displacement.

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According to some reports of seismic evaluations of existing reinforced concrete buildings, the presence of RC buildings with low strength concrete has been confirmed. To evaluate residual seismic performance of those RC buildings accurately, it is necessary to clarify the ultimate strength and the restoring force characteristics of low strength concrete members. In this study, half-scale three column specimens with low strength concrete and plain bars were tested until they came up to ultimate collapse. Based on resistance mechanism of RC columns without bond, it was proposed to formulate the flexural strength, the shear strength and the restoring force characteristics up to ultimate collapse of low strength concrete columns. The restoring force characteristics of low strength concrete columns calculated by the proposed method showed a good agreement with experimental results.

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In this paper, residual seismic capacity ratio of overall frame, which means the reduction degree of seismic safety margin until the safety limitation of frame, is proposed for the weak-beam RC frame based on energy absorption capacity (exact calculation method). The feature sections, which assume the damage ranks such as slight, minor, moderate, severe and collapse, are then defined based on the engineering demand parameter. The relationship between residual seismic capacity ratio of overall frame and feature sections is also discussed to determine the threshold value of residual seismic capacity ratio of overall frame. The simplified calculation method for residual seismic capacity ratio of overall frame is furthermore proposed employing for the damage information, such as maximum residual crack width of members, obtained at on-site. The simplified calculation method for residual seismic capacity ratio of overall frame is finally applied to the previous test results of two weak-beam RC frames, and its feasibility is discussed. As a result, the damage ranks of 2SH-64 specimen are found similar to each other estimated based on the exact and simplified calculation method. The damage ranks of 1SF specimen are however overestimated by the simplified calculation method.

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Tests on reinforced concrete exterior beam-column joint sub-assemblages with low column-to-beam strength ratio in the range commonly constructed in practice are reported. Story shear capacity of some specimens were 30% lower of the story shear predicted by the flexural strength of the beam or the column at the maximum, although the joints have enough margins for nominal joint shear capacity by 10% to 50%. The decrease of story shear is larger in the case of the column-to-beam strength ratio is equal or near to unit. Column-to-beam strength ratio required to secure lateral strength predicted by the flexural strength of sections is small in the case of that the amount of transverse reinforcement in the joint is large, the column depth is large relatively to the beam depth or bent bar anchorage is used instead of mechanical anchor with headed bars.

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This paper extends a kinematic model named nine DOF model proposed by one of the authors which could predicts the moment capacity and moment at balanced failure of reinforced concrete beam-column joints to apply the model to exterior beam-column joints. Four failure mechanisms of exterior joints caused by moments on the joints are assumed and formulas for calculating moment capacities of exterior joints are derived based on the model and assumed failure mechanism. In the calculation, the yielding of longitudinal bars of beam and columns and lateral reinforcing bars in joints is assumed. The results from the proposed formula compared to experimental results gave accurate prediction.

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High strength bolted friction type joints may have misalignment in the contact plane because of permissible deviation of steel plate thickness and so forth. In the first and the second paper, we proposed analytical method to evaluate the slip load of such joints tightened by turn-of-nut method. The validity of the proposed analytical method was verified, by the fact of the calculated slip load based on the analytical value of the contact force was shown good agreement with the experimental results. This paper shows the slip load applying the proposed analytical method to such joints tightened by torque control method. These slip loads are shown in case of the misalignment on the one side of the main-plates as well as in case of the misalignment on the both sides of the main-plates.

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This paper is a study of the buckling length of columns for the case of subjecting the axial forces corresponding to the overturning moment to the frames whose nodes horizontal displacement is not constrained. In this case, it is shown that taking a column length to the buckling length becomes safe side evaluation, unless the rotational resistance of both sides of columns is low. Moreover, about the buckling length in that case, it is shown that axial deformation of columns may influence to it, and more exact consideration can be performed by considering axial deformation of columns.

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This paper discusses the ultimate strength for the cone type fracture of base concrete from the anchorage of anchor-bolt of exposed-type column base. Nine full-scale specimens of three series were tested to examine the fracture modes and ultimate anchorage strength of exposed-type column base. Based on the test results, the estimation formula of the ultimate anchorage strength for the cone type fracture is proposed considering the contribution of punching shear strength of base concrete, bonding strength of reinforcing bars around anchor-bolts, flexural strength of main reinforcing bars of footing beam and so on. The calculated strengths from the estimation formula agree relatively well with the experimental cone-type fracture strengths.

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The lateral-buckling behaviour of steel beams are affected significantly by the boundary conditions at both ends of the beam. So the strength of the laterally supported beams should be evaluated with considering the condition of the adjacent span crossing the stiffner. The purpose of this paper is to propose the strength index which can evaluate the maximum strength and the residual strength of laterally supported H-shaped steel beams under cyclic loading considering elastic-plastic behaviour.

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Realistic 3D-shake table tests using E-Defense were conducted for full-scale 5-story building specimens with/without dampers to evaluate seismic performance, using ground motions of scales ranging from minor to catastrophic levels. The building was tested repeatedly, inserting and replacing each of 4 damper types. This paper focuses on the second test conducted with bilinear oil dampers. It discusses damper and building specimen, testing and table control methods, validations of test results, various characteristics and control effects of the oil dampers.

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Existing experimental research in bearing force-displacement relationships of vertical joints in wall-type precast reinforced concreted (WPC) residential buildings was widely reviewed. The vertical joints connect adjacent precast concrete walls in floor plans filled with cast-in-place concrete. Restoring force characteristics of the vertical joint springs in seismic static pushover analysis models were determined for a standard type of existing WPC residential buildings. In the pushover simulations of the buildings in the short-side direction, vertical springs reached their maximum strength at the lateral drift ratio R =0.19% and it caused the maximum lateral strength with 0.64 of the base shear coefficient C_Q1, which is defined as a ratio of the lateral force with respect to the building weight. C_Q1 remained greater than 0.4 until R =1.0%, although multiple vertical joint springs lost 70% of their bearing strength. This implies potential of seismic performance evaluation approach for existing WPC residential buildings taking into account damage of the vertical joints.

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Concrete Encased Steel (CES) system consisting of fiber reinforced concrete (FRC) and steel is a new composite structural system proposed by the authors, and is being conducted continuous and comprehensive studies to make it practical. In existing studies, the influence of the axial force ratio, the H-shaped steel ratio, the shear span ratio, the concrete fiber contents ratio (the ratio of fiber volume to concrete volume) and the flange width of H-shaped steel on the deformation capacity were investigated. Also the deformation capacity was examined by using the above five parameters. Then equations to evaluate the deformation capacity were proposed. It is clarified that the proposed equations show good agreement with the test results. In this paper, hysteresis models for CES columns to use the earthquake response analysis are proposed with considering the deformation capacity. The accuracy of the model is verified by comparing with the test results.

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CES structures composed of steel and fiber reinforced concrete have been continuously studied by the authors. Since CES structural system is a new composite structural system, it is expected to design by the Calculation of Response and Limit Strength with nonlinear static analysis or the nonlinear time history response analysis. In this study, A nonlinear static analysis for CES shear walls with different anchorage condition for the CES frame and wall panel was conducted to verify the validity of the analytical modeling. The analytical results for the shear force versus drift angle relationships and the deformation components showed good agreement with the experimental results. It was also indicated through the analysis that the different anchorage method of longitudinal wall reinforcing bars affects little on the hysteresis characteristics of CES shear walls.

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The aim of this study is to develop a model that determines the optimal investment ratios between two buildings for seismic strengthening based on a mean-variance criterion. We introduce a “strengthening investment chart,” i.e., a diagram that shows the mean and standard deviation of the total amount of seismic damage to these buildings for every investment ratio. Assuming that the relationship between the increments in the structural seismic index and the amount of strengthening investment is linear, several conditions are deduced such that a Pareto optimal solution exists on the mean-variance diagram. To determine the optimal investment ratios, a two-step decision-making method is proposed according to which each building is checked for conformance to an aseismic capability requirement before the optimal investment ratios are evaluated on the basis of the strengthening investment chart. Moreover, the usefulness of this investment chart in the determination of the ratios is verified through a numerical example.

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The following two fatal errors in the above-referenced paper are discussed.
1) The size effect is not taken into consideration in Equations (16)-(18).
2) The analysis model does not correspond to the Mohr-Coulomb failure criterion and satisfies no equilibrium with external forces.

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The authors thank Prof. Masahide Murakami for his discussion, and the answers are as follows ;
1) Cohesion, angle of internal friction and shear band caused by localized strain are not influenced by the size of specimen. So the scale effect between mud wall and element specimen is considered.
2) In general, shear capacity of soil is expressed by cohesion and angle of internal friction based on Mohr-Coulomb failure criterion in soil mechanics. We have proposed the method to estimate the cohesion and the angle of internal friction of wall clay from the element tests easily. So it is important to use this method for the estimation of the relationship between lateral loading and deformation of mud wall.

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