The free shrinkage deformation occurring in concrete members is generally restrained by members around one with different stiffness and shrinkage rate, and a restraining ratio which expresses degree of restraining has a major influence on state of shrinkage cracking. Therefore, in order to predict the shrinkage cracking, it is important to get the restraining ratio of concrete members in addition to free shrinkage strain of concrete.
 With this background, in order to prepare eventually a design material for controlling shrinkage cracking with the organized distribution of restraining ratio, an experimental and analytical study to find out the regularity of distribution of restraining ratio in concrete walls was previously performed by authors. Additionally, it was noted that the restraining ratio in a wall with drying shrinkage should be reasonably considered by dividing it into the following two areas.
 (1) Non edge area: the area whose restraining direction is horizontal and distribution of vertical direction of restraining ratio is linear because bending deformation is dominant and Bernoulli-Euler's hypothesis holds. The distribution of restraining ratio in this area can be calculated by replacing a concrete wall with a uniaxial model.
 (2) Edge area: the area whose restraining direction is turbulent and distribution of vertical direction of restraining ratio is non-linear because shear deformation is dominant and Bernoulli-Euler's hypothesis does not hold. This signifies that the distribution of restraining ratio in concrete walls can be potentially predicted by the following policy: (1) First, the distribution of restraining ratio in a concrete wall is calculated by the uniaxial model, (2) Next, the position of areas to which the value calculated at above (1) can be not applied (i.e. edge area) and the value of restraining ratio in those areas is obtained from the design material prepared previously, considering various conditions of concrete walls.
 In this study, the map of distribution of restraining ratio in concrete walls, which is the design material in line with above policy, was created. In particular, the distribution of restraining ratio in concrete walls with various conditions was calculated by FEM analysis. Moreover, the areas to which the value calculated by the uniaxial model can be not applied (peculiar areas) were shown by organizing that result, and restraining ratio and restraining direction in those areas were shown.
 The distribution of restraining ratio shown in the map has the following characteristics.
 (1) The peculiar areas occur at the upper and lower parts of both ends of a wall.
 (2) The position and largeness of peculiar area at lower part of both ends of a wall hardly changes depending on stiffness balance between members. Additionally, the area extends vertically as the shape of a wall is horizontally long. Furthermore, though the area is decoupled by columns and beams with increased number of layer and span, the position of that entire area hardly changes.
 (3) The average restraining ratio at the peculiar area at lower part of both ends of a wall is obtained by adding a constant value (approximately 0.4) to the restraining ratio calculated by the uniaxial model, and the average restraining direction at the area is 30° to 35° in any wall.

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 Exterior tile cladding can suffer debonding or adhesive failures as it ages. Failures that lead to cladding tiles falling from the building are highly dangerous for people passing beneath, and consequently it is vital to be able to identify debonding defects at an early stage to prevent tiles falling. This study was performed to develop high-precision apparatus for the efficient debonding detection of debonding. This paper presents the results of investigations into detection methods using impact acoustics.

 Initially, eight exterior-tile wall specimens were prepared with artificially debonded areas. The type of tiles, bonding materials, debonding interface and debonding depth were different for each sample. Percussion tests were carried out by three professional testers, and diagnostic tests were also performed using two types of existing debonding detecting apparatuses. The professional testers had an error rate of up to 40% in differentiating between bonded and debonded areas, while the error rate using the detecting apparatuses was up to 20 percent. These results reveal the effectiveness of using debonding detecting apparatus, but also the need for clear criteria for the apparatus, as well as the need to improve accuracy of the apparatus for objective and accurate diagnosis of debonding,

 Next, a prototype apparatus which has a highly efficient impact mechanism with a solenoid actuator and a microphone was manufactured. The apparatus was then used to examine suitable analysis methods, using impact acoustics, for detecting debonding and effective method for predicting depth of the debonding. As a result, relative maximum amplitude derived from impact sound waveform detected debonding areas correctly. In addition, the interval between the first and the second peaks of the recorded impact sound waveform showed the possibility of predicting debonding depth properly.

 Further research will be continued in order to establish more effective and accurate parameters and their criteria.

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 This paper presents a method to directly evaluate floor response spectra (FRS) from a specified ground response spectrum (GRS) without time history analysis. In general, floor response spectra are utilized to evaluate seismic design force of secondary systems such as non-structural components and equipment in buildings. The secondary system having small mass is mounted on the building idealized as a single degree of freedom linear oscillator. In this study, target fundamental natural period of the buildings are limited between 0.2 and 2 seconds, because dynamic amplification factors are known to be relatively stable for specified damping factors in this range. The damping factors range from 0.02 and 0.3 in order to cover wide variety of the buildings. In the contrast, the damping factors of the secondary systems are assumed to be less than 0.1.
 Firstly, a solution by double convolution integral of impulse response functions is firstly discussed. By integration, a closed form representing the seismic response in the secondary system is decomposed into four parts in time domain. These are composed of the displacement and the velocity of the building and a secondary system virtually mounted on the ground. In the perfect tuning case, where the building and the secondary system have the same natural period, difference between these responses corresponds to the seismic response of the secondary system. In order to obtain the maximum response, a spectrum difference rule (SPD rule) is employed. Consequently, spectral acceleration corresponding both to the building and the second system is combined with a correlation factor of the complete quadratic combination (CQC) rule developed by Der Kiureghian. This rule is extended to a non-tuning case in the similar manner. This approach is confirmed to improve the accuracy of the dynamic amplification factor compared to foregoing studies through time history analysis. Variation of the smooth FRS based on the SPD rule is accurately traced in accordance with changes of both of the two damping factors.
 Secondary, convenient evaluation method of the dynamic amplification factor in the tuning case is discussed. As a result of semi-empirically formulation, it is cleared that the amplification factor divided by a certain factor is critically governed by the average of the two damping factors of the building and the secondary systems. This factor is identified as a reduction factor for response spectra due to damping. As a result, an explicit formula of the amplification factor for specified damping even without GRS is proposed. The values by this formula correspond to perfectly the same values obtained by time history analysis using simulated ground motions with uniform random phase angles. This result holds for various kinds of combination of two damping factors. In the contrast, the estimated values give roughly mean values compared to the results when observed ground motions are used.
 Finally, numerical examples are demonstrated for representative observed ground motions. It is confirmed that the FRS directly evaluated by the proposed method extremely resemble one obtained by time history analysis in shape.

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 When a steel structure experiences a strong earthquake, damage such as yielding, fracture and recontact, and bolt slip in beams and columns as well as anchor bolt extension and uplift at the column base may occur. These phenomena appear as non-linearity or discontinuity in the load-displacement relationship. Detection of these changes can result in significant and valuable information regarding the evaluation of damage and residual performance.
 The aim of this research is to establish a method which is capable of detecting non-linearity and estimating damage of buildings subjected to strong earthquake ground motions from the absolute acceleration response time history. In a previous paper, we have presented criteria to detect non-linearity in the restoring force using the second time derivative of the absolute acceleration, which is often referred to as snap. In order to investigate the capability of snap in detecting changes in the stiffness of the system, earthquake response analysis of SDOF systems was conducted. The analysis results show that discontinuous jumps, which coincide with the yielding times, can be observed in the snap time histories. It is possible to detect the yielding point by comparing a predefined threshold value with the snap time history calculated from the second order central difference approximation to the second time derivative of the absolute acceleration response time history. Moreover, the effect of noise contained in the absolute acceleration response time history on snap was estimated and a noise reduction technique has been proposed. In order to reduce the unnecessary parasitic noise, it is necessary to conduct down-sampling to a time step. But the value of the time step is arbitrarily decided and it is not validated how much effect that the value of time step has on detection accuracy of non-linearity.
 In this paper, the preferable time interval to conduct down-sampling is theoretically proposed. The minimum time interval is determined by the ratio of the noise contained in the accelerogram to the response acceleration at yielding. If the noise is larger, the time interval should be larger to reduce the effect of the noise. While, the maximum time interval is determined by the natural period of the system. The system having shorter natural period requires smaller time interval. From this discussion, it can be concluded that the noise needs to be smaller than about 7% of the response acceleration at yielding.
 Then, the effectiveness of the proposed time interval for down sampling is validated by response analysis, SDOF systems, with elastic-perfectly plastic type restoring force characteristic, a natural period 0.5, 1.0, and 2.0 seconds, and one of three types of input earthquake are used. It is shown that the median value of the proposed time interval range would provide reasonable detection accuracy for many cases, although the accuracy may be affected by the natural period of the system and the frequency characteristics of the ground motions.
 Moreover, a relationship between the snap and the relative velocity at the yield point is also discussed. Mathematically, the snap and the relative velocity has a linear relationship and it may be useful to estimate the plastic deformation after the yielding. From this viewpoint, the accuracy of the relationship is verified by the response analysis result. In the analysis result, the presumed relationship is observed in a qualitative manner, however, the variation coefficient is quite large. This observation implies that it may be difficult to estimate the relative velocity at the yield point only from the snap.

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 This paper proposes an evaluation method to estimate the maximum response of high-rise reinforced concrete structures, considering the P-δ effect. This effect depends on the order of occurrence of the earthquake motions of varying strengths. Examining two events in which the earthquake motions extend to plastic deformation, the maximum response deformation can be evaluated by the accumulated values of each event. We regard two seismic responses as a consecutive seismic response and evaluate it with an estimate equation for the response increase rate. When a future seismic response does not extend into the plastically deformed region after having experienced plastic deformation previously, the future response deformation shows a different response due to residual deformation of a past earthquake. We arrange the equation to estimate the future response deformation with the quantity of standard deformation and residual deformation.

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 It's expected that near future's earthquake disasters are by huge pulse-type ground motions of an inland earthquake or long-period type ground motions of a subduction zone earthquake. Some concerns about seismic-isolated buildings can be also pointed out as follows:
 1) Extra-large deformation of isolators exceeding the design criteria due to those types of earthquakes,
 2) Degradation of seismic-isolated effects for reduction of acceleration response reduction due to the continuation of the long-time vibration.
 To overcome those problems, authors focus on introducing semi-active control systems on isolation layer. In this study, real time hybrid tests are performed on the mid-story isolated structures with semi-active device using the rotary inertia mass damper encapsulating magneto-rheological fluid (MR rotary inertia mass damper). In this test, isolation layer and superstructure are actually created as the test specimen, and lower part of structure is simulated by lumped mass system model in a computer. By using actual equipment of damper which has not been exactly clarified its behavior, modeling errors seem to be avoided, and the accuracy of the results on the hybrid test can be secured. This paper reports about constructing the system for real time hybrid test, and verifying its validity, moreover verifying the reproducibility of shaking table to confirm the reliability of this test.
 At first, mechanical specification of the experimental system and devices are evaluated. Steady vibration tests by sinusoidal waves are carried out on MR rotary inertia mass damper, and then its mechanical properties are modeled for numerical evaluations. The modeled formula is confirmed to agree to the experimental value, and is considered reasonable. A control time lag is observed when semi-active control is performed. This time lag is considered on the first-order delay system, and is also evaluated from experimental data. By considering this time lag effects on the numerical simulations, the precise experimental results can be gained. Lots of cases of the real time hybrid experiments for various types of earthquake input motions are operated. Those results are also compared with the numerical results by the fully modeled analyses, and the validity of the testing system, the modeling of this damper and the identification of the specimen are confirmed. Moreover, performance and the reproducibility of the real time simulators, which is actualized as the displacement of the shaking table, are evaluated.
 As results, high reproducibility of displacement of the shaking table by real time calculation could be observed and controlling errors could be manipulated to be negligible. At the same time, generated accelerations on the shaking table are observed performing accurately. However there is a little error in the reproduced acceleration for some cases. As a concluding remark, it is confirmed that reliable experimental system to operate real time hybrid test is constructed through this research.

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 Research and development of structural health monitoring (SHM) of a building is vigorously proceeded in the resent academic research, which can help early recovering of urban facilities after a serious disaster such as a strong earthquake or wind, or reliable checking of structural integrity of facilities against the deterioration. Of SHM, vibration based-damage detection (VBDD) is considered promising to make a structural diagnosis of a building, where modal properties or stiffness are compared before and after the severe event. Story stiffness identification is one of the powerful tools in the VBDD, which can detect damage locations and the amounts in a damaged building. In a steel moment frame building, however, the seismic failures can be often appeared locally to be concentrated to the parts of the beam-ends, since vibration energy is dissipated in the plastic hinges at beam ends in seismic design: therefore one must firstly evaluate whether beam-ends are damaged or not. The traditional story stiffness identification scheme might not be useful in the SHM of steel building, since changes in the story stiffness due to the beam-ends damage should appear simultaneously on the upper and lower stories.
 In the paper, a vibration-based system identification procedure of a lumped mass-spring-stick typed fish-bone model is proposed, in order to detect damage locations and their amounts in a steel frame building suffered damages at beam-ends. The fish-bone model has a rotational stiffness on every story, therefore, by using distributions of rotational stiffness, one can easily detect a severe story damaged with beam-end ruptures. A system identification scheme of a fish-bone model using Extended Kalman filter (EKF) is proposed, where rotational stiffness estimates at each story are identified as unknown parameter under the assumption that no columns are damaged: i.e., bending and shear stiffness in columns can be given as a priori. The effectiveness of the proposed method is verified by numerical simulation using the three-dimensional (3-D) frame model, and by real-life records on shaking table tests conducted in the E-defense of the world-largest shake table. By evaluating the transition of the rotational stiffness on the steel frame specimen, detectability of beam-end damage is also discussed. The main results in the paper are summarized as follows:
 1) The identification scheme to the fish-bone model is theoretically derived with applying to the EKF by using the partial differential inverse matrix formula. Firstly, the equations of motion and the identification scheme are derived with consideration only the bending deformation of the beams and columns. Secondly, the identification was extended to consider both bending and shear deformations of beams and columns in the fish-bone model. The derived identification scheme is verified in numerical simulation of the 3-D frame. As a result, the rotational stiffness of the beam can be well-identified even when the members behave in three-dimensional deformations such as bending, shear and axial deformations.
 2) Beam stiffness of the shaking table test specimen is evaluated by the proposed identification scheme, where observation record of the closely real-life specimen and closely real-life damage were tested in the E-defense. Each identified parameter of rotational stiffness is converged to a constant value in those experimental demonstrations. It is clarified that rotational stiffness of the beam can be well-identified for applying the real-life records.
 3) As a result on several identifications of the rotational stiffness in several quake-experienced states, it can be evaluated that the estimates of the rotational stiffness of the beam decreased with the progress of a series of the shaking table tests. The distributions of the rotational stiffness are shown promising to detect beam-ends ruptures on a steel moment resisting frame structure.

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 In a structural design of spatial structure composed with truss beams, each truss beam is often replaced by a continuous beam. Although such replacement is restricted to the elastic problem, it is useful in the allowable stress design process. However, structural designers need to examine nonlinear behaviors like a collapse behavior of a target structure to ensure true safety of the structure. To simulate such behaviors accurately, the numerical model is often applied in which all members in at least a few truss beams are divided by elements. This numerical model with huge degrees of freedom can be calculated by making use of modern high-tech computers. But considering its high cost and unsuitability in an actual design process, we have suggested a new beam element called “truss beam element”, which enables us to simulate the buckling behavior of chord members in truss beams. In our previous papers, the boundary condition of the chord member was assumed to be simple support. However, this assumption is not always hold in simulations of actual spatial structures, since truss beams are rigidly connected to each other in structures. Therefore, the truss beam element should be extended to the truss beam problem of chord members connected rigidly.
 In this paper, extracting only a chord member in a truss beam, we derive the formulation for the chord member which is subject to uniform intermediate longitudinal forces and moments at both ends. We also extend the section of the chord member which was restricted to rectangular shape to an arbitrary one.
 Based on the thermodynamics, the formulation is derived by using the collapse mechanism for the extracted chord member which is subject to the load mentioned above. As a result, elastic constitutive equations are found for an average longitudinal force, a slope of longitudinal force and moments act on three plastic hinges at both ends and a middle point. Simultaneously, the equilibrium of moment at the middle plastic hinge and the dissipation term at plastic hinges are found. According to the principle of the maximum plastic dissipation, the plastic flow rule for the collapse mechanism is obtained by taking account of the yield surface for plastic hinges. These equations can be reduced to the pinned joint situation when the moments at the both ends are zero, which means the present method for the chord member includes the previous one.
 The accuracy of the present method is examined numerically through the comparison between the results by the present method and those by the discrete method. We executed four cases of numerical examples with tube cross-section; case (i) {slenderness ratio(λ)=40, longitudinal force number(S)=2, slope of longitudinal force(N_i/N_j)=0.8}, case (ii) {λ=80, S=2, N_i/N_j=0.8}, case (iii) {λ=40, S=2, N_i/N_j=-0.6}, and case (iv) {λ=40, S=4, N_i/N_j=0.4}. The relationships between the longitudinal force and displacement at the left end obtained by the present method agree with the ones by the discrete method, except for the process of partially yielding in cross section. In addition, the relationships between the moment and the longitudinal force at each hinge are also in accord. Hence, the present method suggested here can evaluate the local nonlinear behavior in chord member as only element.
 In our future work, this method will be extended to the truss beam element.

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 We proposed a simplified evaluation method for normalized force which means the ratio of each pile in the pile group to single pile on the ultimate ground reaction force. We use beam-spring model for the purpose of back calculation of the ultimate ground reaction force at each pile based on three-dimensional elasto-plastic analysis.
 As a result, we found that the following trends from i) to iv).
 i) The distribution of normalized force for sandy soil and clay soil are different. For sandy soil, the normalized force in the front row pile to the loading direction is largest and decrease sharply in the second row pile. From the third row pile to the back row pile, the normalized force shows the linearly decreasing characteristic. For clay soil, the normalized force decrease once toward the center row pile from the front row pile, it shows a tendency to be constant substantially toward the back row.
 ii) Both sandy soil and clay soil, if pile's interval is wide enough, the ultimate ground reaction force is as same as that of single pile. On the other hand, if pile's interval is narrow, the ultimate ground reaction force is less than that of single pile and it means that the normalized force is less than 1.0.
 iii) We proposed a simplified evaluation method for normalized force considering above trends of i) and ii). For sandy soil, the normalized forces in the front row pile, the second row pile and the back row pile are formulated. The normalized forces between the second row pile and the back row pile are assumed to be determined by linear interpolation.
 iv) For clay soil, the normalized forces in the front row pile and the center row pile are formulated. The normalized forces are assumed to be determined by linear interpolation between the front row pile and the center row pile, and to be constant from the center row pile to the back row pile.

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 1. Introduction
 In Japan, high performance damping buildings and houses are required to improve seismic safety and to minimize damage, because of many occurrences of severe earthquakes. On the other hand, Japanese wooden houses do not have enough shear walls to keep large and many openings and semi-rigid timber portal frame has been developed and has increased. However, semi-rigid timber frame structure is relatively soft. This paper presents seismic performance of semi-rigid timber frame structure with damper through full-size shaking table tests. We compared response deformations during moderate and severe ground motions among only frame, frame with oil damper and frame with shear wall to verify damping effect of oil damper.
 2. Overview of damping wall with oil damper
 Damping wall system consist of a oil damper set horizontally through a ∧ shape steel member installed between two columns and below a beam of wood (hereinafter, referred to as "∧-type damping wall"). ∧-type damping wall is a system where damper deformation becomes almost the same as the story deformation. ∧-type damping wall has a high damping force compared to other damping walls that exist in the field of wooden houses nowadays in Japan. Relief force of the oil damper is 12 kN and the relief velocity is 70 mm/sec.
 3. Overview of shaking table tests
 Planar shape of box-shaped one-story specimen is 5460mm (direction of vibration) × 3640mm (Orthogonal direction of vibration), and its height is 2835mm. Ground motion is input in one direction. There are three types of structures set in series in the direction of vibration, the outer two structures are semi-rigid timber frames and the structure at the center is ∧-type damping wall or seismic wall of plywood. The detail for each structure is described as follows. (1)Semi-rigid timber frame with oil damper. (2)Semi-rigid timber frame with seismic wall of plywood. (3)Semi-rigid timber frame only. The total weight of specimen is 87.0kN.
 Moment resisting joint of semi-rigid timber frame is using lagscrewbolt, metal connector and nut. Procedure of construction is embedding the lagscrewbolt into the column and beam, and setting up a metal connector, and binds with nut. Size of column is 120mm × 300mm and wood specimen is engineering wood of European red pine (E105-F300). Size of beam is 120mm × 360mm and wood specimen is engineering wood of European red pine (E105-F300). For column base anchor bolt (M14, SNR490B) with growth capacity was used. Semi-rigid timber frame is considered to have a Co=0.51 seismic performance for elastic frame analysis. Seismic walls are placed in the center of structure row and are bonded both sides of plywood (t=12, N50 nail, @150). Seismic performance of this wall is almost equivalent to ∧-type damping wall. ∧-type damping wall and Seismic wall are considered to have a Co=0.11 seismic performance.
 Input seismic wave are three observation waves and one artificial wave. Observation waves are "ELCENTRO 1940 NS", "TAFT 1952 EW" "JMA Kobe 1995 NS". Artificial wave is "BSL wave" whose acceleration response spectrum is provided in the Building Standard Law. Seismic waves were scaled to two levels that represents medium and extreme earthquakes.
 4. Results and Conclusions of shaking table tests
 Maximum response deformation of " Semi-rigid timber frame only " for Taft wave(25kine) is 1 / 106rad, for BSL wave(80%) is 1 / 45rad. This is large response deformation by specific seismic wave. "Semi-rigid timber frame with oil damper" reduces the response deformation for all evaluated seismic waves and can avoid damage to the structure.

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 There are many traditional wooden houses forming historical townscapes in Japan. Microtremor measurements can be useful to evaluate seismic performance of these houses easily because microtremor measurements is conducted in a short time without any destruction. Although several researches estimate seismic capacity grade or yield base shear coefficient of houses based on the natural frequency which is obtained from microtremor measurements, these researches do not evaluate the maximum response deformation angle of houses against earthquake ground motions.
 In our previous study, we have proposed the amplitude dependency of vibration characteristics such as natural frequency and damping ratio based on shaking table tests of wooden frame specimens. Applying this amplitude dependency of vibration characteristics into response spectrum method, the maximum response deformation angle of wooden frame specimens against an input wave has been estimated approximately. In this paper, we develop the amplitude dependency of natural frequency which can be applicable for existing traditional wooden houses and establish the maximum response deformation angle evaluation method using microtremor measurements and the amplitude dependency of natural frequency.
 In this study, response spectrum method is used to evaluate the maximum response deformation angle. First, a traditional wooden house is modeled into the two degree of freedom model. The two degree of freedom model is converted into the equivalent single degree of freedom model. The maximum response deformation angle is evaluated from the intersection of a predicted acceleration response spectrum and the equivalent response spectrum. The equivalent response spectrum is calculated from the natural frequency and the amplitude dependency of natural frequency which is proposed in this paper.
 The amplitude dependency of natural frequency is expressed as the ratio of the equivalent natural frequency of traditional wooden houses to the natural frequency. Equation of the amplitude dependency of natural frequency is established based on the results of seismic observation of three wooden houses in Kyoto, shaking table tests of two-storied traditional wooden frame specimens and static lateral loading tests of full wall specimens. The equation of the amplitude dependency of natural frequency consists of three elements: a) the natural frequency, b) the ratio of the equivalent natural frequency at 1/1000rad to the natural frequency and c) the ratio of the equivalent natural frequency at more than 1/1000rad to the equivalent natural frequency at 1/1000rad.
 To confirm the accuracy of the proposed maximum response deformation angle evaluation method, the maximum response deformation angle on the first story of the full scale specimens of shaking table tests is evaluated. As an application example, simulation analysis using this proposed evaluation method is conducted against several acceleration response spectra changing the natural frequency of houses. The major findings from the simulation analysis are summarized as follows.
 1) The maximum response deformation angle on the first story decreases as the natural frequency of houses increases in case of design spectra in Japan. Therefore, it is effective to increase walls and strengthen houses against design spectra in Japan.
 2) In case of pulse-like ground motions, the maximum response deformation angle on the first story do not change so much by the natural frequency. Therefore, it is important to increase deformation capacity of houses against pulse-like ground motions.

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 Static loading tests to reinforced concrete (R/C) three-dimensional (3D) corner column-beam subassemblage specimens were carried out by Katae and Kitayama (2014) to investigate the effect of column compressive axial load on failure mechanics of joint-hinging proposed by Shiohara. The Shiohara's proposal pointed out that failure mode of a R/C beam-column-joint frame depends greatly on a column-to-beam capacity ratio and joint-hinging failure tends to develop when a column-to-beam capacity ratio is close to unity. Note that a column-to-beam capacity ratio can be varied by changing not only the magnitude of column axial load but also the amount of column longitudinal reinforcement.
 Therefore three 3D corner column-beam subassemblage specimens (two without slabs and one with a slab having a thickness of 70 mm) were tested under bi-lateral loading and constant column axial load where a column-to-beam capacity ratio of 1.5 and 2.6 was set by placing column longitudinal reinforcement of 8-D16 and 8-D19 respectively. All 3D subassemblage specimens failed in joint-hinging with an increase in story drift.
 It is revealed by Katae and Kitayama (2014) that the ultimate flexural capacity of corner column-beam joints under bi-lateral loading can be estimated based on the new mechanism of joint-hinging by assuming that the orbit on the rectangular coordinates plane defined by joint-hinging capacities in both directions orthogonal to each other traces an ellipse curve under bi-lateral loading. Three-dimensional (3D) failure surfaces and stress flow conditions in a corner column-beam joint under bi-lateral loading, however, are not clarified yet. Then a 3D joint-hinging failure model was constructed for a corner joint based on test results referring to a plane joint-hinging failure model proposed by Kusuhara and Shiohara. A quick evaluation method for the ultimate joint-hinging capacity was proposed based on the 3D failure model in a corner column-beam joint under bi-lateral loading.

 General conclusions are drawn from the study as follows.

 (1) When a column-to-beam capacity ratio increased from 1.5 to 2.6, the ultimate joint-hinging capacity computed as a resultant force of two orthogonal story shear forces under bi-lateral loading increased to 1.19 times by large amount of column longitudinal reinforcement. This indicates that the ultimate joint-hinging capacity was enhanced by the increase in a column-to-beam capacity ratio due to increasing the amount of column longitudinal reinforcement.

 (2) When a column-to-beam capacity ratio was changed from 1.5 to 2.6 by the increase in the column compressive axial load in past tests or the amount of column longitudinal reinforcement in this tests, the column compressive axial load had a greater influence on enhancement of the ultimate joint-hinging capacity under bi-lateral loading than the amount of column longitudinal reinforcement.

 (3) A slab contributed to enhancing the ultimate joint-hinging capacity by 1.07 times that without a slab for 3D corner column-beam subassemblages with a column-to-beam capacity ratio of 1.5, failing in joint-hinging. Torsional moment at the end of a transverse beam caused by tensile force of slab reinforcing bars in the longitudinal direction, whose rotating direction is counter to that of upper and lower columns, is carried to a beam-column joint and restrains rotation of the upper and lower columns. This is the reason for enhancement of the ultimate joint-hinging capacity due to a slab.

 (4) Proposed method based on 3D failure model herein can adequately evaluate the ultimate joint-hinging capacity of a corner column-beam joint under bi-lateral loading since there is a discrepancy within 10 % between predicted ultimate capacity and test result.

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 1. Introduction
 Exterior/partition flat walls in concrete buildings were severely damaged by the 2011 earthquake off the Pacific coast of Tohoku. Concrete buildings lose their function due to failure of non-structural walls nevertheless structural components are not damaged significantly. Earthquake-damaged buildings are generally judged to be restored/demolished according to the guideline for post-earthquake damage evaluation⁵⁾ in Japan. After the 2011 Tohoku earthquake, however, several specific problems have been clarified when applying it to ductile concrete buildings with damage to flat walls as follows: 1) structural performance of flat walls is not clear, 2) damage to flat walls causes loss of serviceability even though they are regarded as non-structural components, and 3) structural damage grade seems to be overestimated when damage to flat walls is considered for the damage evaluation. Therefore, this paper summarizes such specific problems focusing on an example of earthquake-damaged ductile concrete buildings with typical damage to flat walls, and discusses the effects of the flat walls on the seismic behavior/performance of this type of building.
 2. Specific problems in post-earthquake damage evaluation
 This study focuses on an 11-story steel reinforced concrete residential building in Sendai which was damaged by the 2011 Tohoku earthquake (Figs. 1-2, Photo 1). Exterior/partition flat walls were constructed in the longitudinal direction and suffered severe damage (Photo 2, Figs. 3-5). On the other hand, minor damage was observed to structural components. Damage grade of the building was classified into “heavy”/“moderate” evaluated considering with/without the damage to the flat walls according to the Japanese guideline (Table 1). It indicates one of the specific problems caused by the damage to the flat walls. Therefore, this study investigates the effects of the flat walls on the earthquake response/seismic performance of the investigated building through numerical simulations.
 3. Analytical modeling for numerical simulations
 Two-dimensional frame analyses were conducted to clarify the effects of the flat walls on the earthquake response and seismic performance of the investigated building in the longitudinal direction. The building was replaced by two analytical models (CaseA/CaseB) considering without/with the flat walls (Figs. 6-10). In the case of CaseB, the flat walls were represented by the Isoparametric Element model which was previously verified in Reference 12) (Fig. 12).
 4. Building damage simulations
 Earthquake responses of both models were evaluated using the NS components of ground motion records which were observed about 2.7 km far from the building during the 2011 Tohoku earthquake (Figs. 1 and 13). Consequently, CaseB considering the flat walls simulated well the real damage to the components of the buildings (Figs. 16-18), which means that the flat walls affected the building responses by the earthquake. This was caused by softening in the lower stories with stiffness/strength deterioration of the lower-stories flat walls, which also resulted from a pushover analysis for CaseB. In contrast, CaseA neglecting the flat walls could not simulate such drift/damage concentrations in the lower stories.
 5. Conclusions
 This paper summarizes and discusses specific problems for post-earthquake damage evaluation caused by damage to flat walls in ductile concrete buildings. One of the problems was unknown effects of the flat walls on the seismic behavior/performance of this type of building. Therefore, the flat wall effects were investigated and exemplified through numerical simulations of a typical earthquake-damaged residential building suffering significant damage to the flat walls in the 2011 Great East Japan earthquake.

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 When a reinforced concrete flexural member is designed against shear loads according to the AIJ standard for reinforced concrete structures, bond performance between reinforcing bars and concrete should be verified. The bond splitting strength in the AIJ standard is based on pull-out test results of longitudinal deformed bars embedded in concrete. The bond strength is evaluated as shear stress on the surface of the bars. On pull-out test of deformed bars, bond strength of the deformed bar in second layer is apparently lower than that of the bar in first layer because of influence of bond stress in the first layer. In the AIJ standard, the bond strength in the second layer is simply reduced multiplying by 0.6. However, on bending-shear test results of R/C beams, when the deformed bar in second layer cut off, the bar performs higher strength. That is because bond stress distribution in the first and second layers is different from the case that all the double layered bars are arranged continuously through the span of beam. On the other hand, although more than three layers of longitudinal bars are arranged in foundation beams these days, the provision in the AIJ standard doesn't show methods for the bars more than three layers. It is necessary to consider the bond stress in all the tension bars totally in order to evaluate the side-splitting bond strength.

 In this paper, evaluation method of the side-splitting bond strength is reviewed in order to examine bond performance of the R/C beams with multi-layered longitudinal bars including cut off bars.
 The previous pull-out test results and bending-shear test results were reviewed in order to avoid side-splitting bond failure of the beams arranged more than three layers and including cut off bars. As a result of the revision, a new method for evaluating tensile force of all the longitudinal bars at the side-splitting bond failure is proposed. In this method, the direct shear failure of the concrete at the reinforcement layer is considered rather than the bond stress of each bar. The tensile force at the bond failure is expanded and simplified from the bond strength provided in the Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Inelastic displacement Concept published by AIJ in 1999. However, the bond stress on the bar surface should be verified for local bond failure of the cut-off bar, corner-splitting failure, and V-notch splitting failure. If bond strength of cut-off bar in the second layer is estimated higher than the present provision, although it is the result observed in the loading test of the beam, a problem may occur. The problem can be avoided when the proposed method is adopted.
 In order to examine the new method, the tensile force at the bond failure was applied to shear strength formula provided in the 1999 AIJ Guidelines. It is rational to avoid the side-splitting bond failure by examine the shear capacity of the beams. The 1999 AIJ guidelines provide T_x, which is the bond strength, in the shear strength formula. In this paper, the proposed method was applied to T_x. The modified shear strength formula is verified by comparing with the previous test results. The test results of the R/C beam specimens of single, double and more than three layers arrangement, and the specimens including cut off bar, were selected. As the results of comparison, the modified method shows good agreements with the test results with almost the same accuracy as the method in the 1999 AIJ guidelines.

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 A high degree of seismic safety is required in nuclear power plants. To evaluate accurately the seismic behavior of a nuclear reactor building, it is effective to use an analysis model that takes in-plane shear characteristics of the floor slab into consideration. However, few experimental studies of the in-plane elasto-plastic shear characteristics of the floor slab that is constantly subjected to out-of-plane dead and live loads have been reported. Therefore, fundamental data needed to decide on restoring force characteristics and shear strength to be used for an analysis model is insufficient. In this study, the static loading tests were carried out to identify the elasto-plastic behavior of a reinforced concrete floor slab subjected simultaneously to uniformly distributed out-of-plane load and in-plane shear force.
 Prior to test planning, as a first step, a fact-finding survey was conducted to collect data on representative nuclear power plants in Japan including the dimensions (length, width, thickness) of typical floor slabs, dead loads, live loads and the amount of reinforcement. The configuration of test specimens and test parameters were determined on the basis of the results thus obtained. A total of seven test specimens were prepared, and the amount of reinforcement and out-of-plane distributed load level of the floor slab were used as parameters. The configuration of the test specimens is basically the same as that of specimens for a typical sheer wall test. In the tests, first, distributed loads were applied to the specimen as out-of-plane forces and were kept constant, and, next, in-plane shear forces were applied.
 The results of the tests revealed that cracking patterns and the in-plane failure mode depends on parameter differences. The test results also clarified the effects of each parameter on the load－deformation relationship and in-plane shear strength. Using the experimental results thus obtained, the strain behavior of reinforcing bars, deformation components, a method of setting restoring force characteristics in analysis model were studied in detail. Also, a method of evaluating in-plane shear strength taking account of the influence of out-of-plane forces was proposed. From the results of this study, the following conclusions can be drawn:
 (1) Within the range of out-of-plane force acting on a floor slab of a typical nuclear power plant, the influence of out-of-plane force is small, and the failure mode due to in-plane shear is similar to shear failure of a wall.
 (2) In practicing the evaluation of the earthquake resistance of a nuclear power plant, the in-plane shear behavior of a floor slab can be evaluated by using the restoring force characteristics model for a shear wall shown in JEAC4601-2008.
 (3) In cases where out-of-plane force exceeds the limit considered in the standard design process, as out-of-plane force increases, the influence of punching shear failure due to out-of-plane force tends to increase and in-plane shear strength tends to decrease.
 (4) By referring to previous studies, a method of evaluating the in-plane shear strength of a plate member in the case where it is subjected to uniformly distributed out-of-plane loading has been proposed. The proposed method makes it possible to accurately evaluate the in-plane shear strength of a floor slab subjected to a large out-of-plane force exceeding the limit assumed in the design.

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 Unbonded prestressed concrete structures have been attracting attention in terms of their excellent low damage performances. They are able to sustain seismic force with small residual deformation. Unbonded prestressed concrete members may crack for large scale earthquakes but cracks tend to close due to the prestressing force. In order to fully take advantage of low damage characteristics of unbonded prestressed precast concrete structures, it is important to develop a numerical model to simulate their structural performance with high accuracy. This study focuses on developing a simple fiber based model and simulating damage of post-tensioned precast concrete members for function continuity and quick recovery.
 In experimental part, damage evaluation was conducted using six unbonded prestressed concrete beams. In this study, four limit states (Serviceability limit state, Reparability limit state I, Reparability limit state II and Safety limit state) of unbonded prestressed concrete beam are defined based on the 2015 AIJ prestressed concrete guideline¹³⁾. Drift angle of specimens at each limit states was determined by considering strain and stress state of concrete, tendon and mild steel reinforcement, residual crack width and residual drift angle. As a result, the drift angle of the specimens at each limit states were determined.
 In numerical part, damage evaluation was conducted using a proposed fiber-based model. For damage evaluation, it is important to simulate hysteresis curves for unbonded prestressed concrete members with different material properties. The hysteresis characteristics of unbonded prestressed concrete members have been studied for many years. Many of them are used for design purposes but unable to predict hysteresis curves and damage states. In addition, very few models are able to simulate unloading part of hysteresis loops with good accuracy. Since the unloading part is a key factor to determine residual displacement, it is quite important to evaluate residual crack width and deformations.
 This study proposes a fiber-based model to simulate unbonded prestressed concrete beams. In this study, beam end displacement was assumed as the sum of four components. The components are rocking displacement, flexural displacement, shear displacement and slip displacement between beam and stub. The rocking displacement of beam is calculated using the fiber-based model, the flexural and shear displacement of beam was assumed as elastic, and the slip displacement is ignored in this simulations since it is small in the experiment. The model consists of fibers for cover concrete, core concrete, mild steel reinforcement, and unbonded prestressing tendons. Length of fiber elements were varied to consider effects of unbonded prestressing tendons. Menegotto-Pinto model was used for tendons; bi-linear model was used for mild steel reinforcement; and modified Kent-Park model was used for cover and core concrete. The proposed model was validated using four post-tensioned concrete beams.
 After all, the proposed model simulated hysteresis loops of tested specimens with good accuracy. Furthermore, drift angle of the specimens at each limit states was calculated using analytical data in the same way as experimental part.

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 When the building is subject to a seismic load, columns will subject bending moment and axial force simultaneously. Therefore, it is important to design the column under these combined loading in the ultimate limit state to guarantee the safety. Recommendation for Limit State Design of Steel Structure (LSD) specifies the requirements for columns to guarantee sufficient strength and ductility. In Japan, widely used shape for columns are square steel tubular column. However, the requirements stipulated in LSD are based on the test results that were conducted by H-shaped steel columns in 1980s. Test results that can confirm the appropriateness of LSD requirements for square steel tubular column are limited. It is necessary to gather more data of maximum strength, deformation capacity, and elasto-plastic behavior of square steel tubular columns by testing. Moreover, column that is subjected to compressive axial force is important to take into account second-order effects.
 In this study, testing where axial force and bending moment are applied to the columns simultaneously are conducted. Maximum bending moment, deformation capacity, and second-order effect that will be caused by Pδ moment were evaluated from the test results. Comparison between LSD requirements and test results were also shown.
 From the test results, followings are found.
 1) Square steel tubular column which satisfies width-to-thickness ratio classification P-I-1 and column classification C-1 of LSD had full plastic limit strength which is stipulated in LSD.
 2) Three types of collapse mechanism are confirmed.
 i) Local buckling occurred at the end of the column determined the ultimate state.
 ii) Pδ moment determined the moment capacity at the loading point, and local buckling occurred around the most deflected portion determined the ultimate state.
 iii) Pδ moment determined the moment capacity at the loading point, increment of the deflection around the middle portion of the column determined the ultimate state. Local buckling was not observed during the testing.
 Collapse mechanism that will be categorized to iii) can be observed to the columns that are located further from the LSD limitation.
 3) Plastic deformation capacity obtained from testing showed larger values than that stipulated in LSD, even if the column does not satisfy the LSD requirements.
 4) When the plastic deformation capacity R of the column is determined by Pδ moment, the plastic deformation capacity R and the value of n_y·λ_c0² are in a linear relationship. Some of the columns which had larger width-to-thickness ratio observed local buckling; therefore, plastic deformation capacity of the column will be determined either Pδ moment or local buckling. Therefore, it is also important to evaluate quantitatively the plastic deformation capacity which is determined by local buckling.
 5) When the collapse mechanism of the column is determined by Pδ moment, the maximum deflection appeared around the middle of the column which is not expected in structural design. From the point of view of deflection, LSD provides a reasonable limitation to guarantee the expected mechanism where the plastic deformation will concentrate at the end of the column.

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 1. Introduction
 Concrete-encased steel (CES) structural system consisting of fiber-reinforced concrete (FRC) and encased steels is a new composite structural system. Continuous and comprehensive studies are currently being conducted to make this system practical. In existing studies, the ultimate strength of CES columns were calculated using the strength superposition method based on test results. However, for CES columns in which FRC is used, the contribution of the confinement effect to the structural performance remains unclear. This study discusses the evaluation of the strength and confinement effect of FRC based on test results.

 2. Investigation of the crack strength of FRC and CES members
 Material tests on FRC were conducted. Results clarified that the crack strength of cover FRC was the same as that of normal concrete. The crack strength of CES members can be calculated using the existing evaluation formula of RC members.

 3. Investigation of the bending strength of FRC
 Eccentric compression tests on FRC short columns were conducted. Selected test parameters were eccentric distance (axial load ratio) and loading directions (uniaxial or biaxial). Using the AIJ-SRC formula, the ultimate flexural strengths of all specimens were found to be at least 1.0 times that of design ultimate strengths. The application scope of this formula is for encased reinforced concrete and not for encased FRC in this study. Thus, the current AIJ-SRC formula can be conservatively used for FRC. The accuracy of fiber analysis was verified by comparing with test results.

 4. Investigation of the local buckling reinforcement by FRC
 Seven columns were tested under axial compression loading to investigate the effects of width-to-thickness ratio and synergistic interaction between cover FRC and encased steel. Selected test parameters were composite or non-composite columns (steel, FRC, and CES) and width-to-thickness ratio of encased steel. Increase in steel strength by buckling due to confinement can be expected for cover FRC. Based on test results, AIJ design formulas for SRC structures can be applied to evaluate the ultimate strengths of CES columns with large width-to-thickness ratios.

 5. Conclusion
 The evaluation method of the structural performance of the CES structure was investigated. Main findings are summarized as follows.
 1) Crack strength and bending strength of FRC applied to the CES structure are equivalent to those of normal concrete. However, the toughness of FRC improves according to the effect of fiber.
 2) From the result of 1), the crack strength of CES members can be determined using the evaluation formula of RC members.
 3) The stress block by AIJ-SRC standard can be estimated the strength of FRC under the axial force and bending moment. Furthermore, according to fiber analysis, the accuracy of strength evaluation improves.
 4) FRC influences the local buckling reinforcement of encased steel. Therefore, FRC is believed to restrict the width-to-thickness ratio of the encased steel of CES members. 1. Introduction

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 It was confirmed that when the ground at the back of the L-type retaining wall was improved using cement, the value of horizontal earth pressure became almost zero after the improved part of the ground hardened a few days later (2009). It was also revealed that when overburden load was place on the back of the retaining wall, no horizontal pressure was created since the retaining wall and the improved part of the ground were integrated into a whole. Furthermore, it was confirmed that the larger was the ground improvement range (θ), the larger were the stability moment at the time of overburden loading and the friction resistance at the underside of the batholith, making retaining wall displacement smaller.
 From the aforementioned studies, ample knowledge about the ground improvement effect at the back of the retaining wall was gained. On the other hand, however, it is practically impossible to discuss the ground improvement effect in detail because earth pressure acting on the ground improvement boundary surface was not measured and because there was only one type of overburden loading position.
 Due to the aforementioned reasons, in this study, various experiments are to be conducted by creating a device which made it possible to measure earth pressure acting on the ground improvement boundary surface and using the ground improvement shape and the loading position as the parameters, and the relationship between the ground improvement shape ad the ground improvement effect is to be examined.
 The key results obtained from this study are as stated below
 (1) On Incremental Earth Pressure Distribution
 When surface load is imposed on improved soil (a = 0cm, 10cm), the earth pressure has an incremental distribution where the earth pressure is higher at and around the central part and decreases in the directions of the earth’s surface and the batholith, respectively. In the case of the test object [θ= 15°], too, the value for the earth pressure reaches a maximum level at a point approximately 2H/3 away from the earth's surface and then decreases in the directions of the earth's surface and the batholith, respectively. In the case of the test object [θ= 30°], on the other hand, the value for the earth pressure reaches a maximum level at points above the central part and decreases in the directions of the earth's surface and the batholith, respectively.
 When there is no surface load imposed on the improved soil, the values for the incremental earth pressure ([θ= 0°; a = 20 cm], [θ=15°; a = 30 cm], [θ= 30°; a = 40 cm]) have distributions similar to each other, increasing in the direction of depth. The value at each point is far smaller than when a = 0 and a = 10 cm.
 (2) On Ground Contact Pressure Distribution
 Due to the relationship between the surface load (q = 10kN/m²) and the ground contact pressure, the test object [θ= 15°] has a relatively uniform ground contact pressure distribution for every loading position. It has also been shown that the test object [θ= 30°] has the most unbalanced ground contact pressure distribution.
 (3) On the Relationship between Overburden Loading and Displacement
 The displacement that results from overburden loading for the test object [θ= 30°] is the smallest, it becoming larger for the test object [θ=15°] and for the test object [θ=0°], in that order.

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