From the results obtained in this study, it is concluded that the quantity of bubbles that PC-n, which is polycarboxylate having poly (n) ethylene glycol groups as side chains, introduces in concrete can be reduced when the side chains' length ‘ n’ is designed to be longer than 25 mol. But basically it is suggested that PC-n would have the air entraining performance in itself; By using the specific AE agent and anti-foaming agent, the stable bubbles can replace the unstable ones PC-10 introduced in concrete. As a result the excellently durable concrete can be manufactured that maintains the relative dynamic Young's modulus beyond 90% till about 1,200 cycles.

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In this paper, it is shown that a crack prediction analysis for drying shrinkage of wet finishing plastering materials on the external wall. In this analysis, the drying shrinkage strain in the mortar is determined by proposal measurement procedure for the age. The internal stress in the finishing mortar is analyzed by finite element method based on the plane stress problem for the drying shrinkage strain derived from experimental measurement. We illustrate the method which predicts the crack generation point and time in finishing mortar. This present method is formulated by two-dimensional finite element method to apply the crack prediction for the opening on wall corners. The effectiveness of present method is verified by comparing the numerical results with the experimental tests. We investigate analytically the typical characteristics of the drying shrinkage of the external wall using wet finishing plastering material by numerical studies.

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In this paper, we analyzed the damage of reinforced concrete buildings due to the 1923 great Kanto Earthquake in the City of Tokyo based on the major two damage investigation reports. One is made by the Shimizu-gumi construction company, which is newly analyzed in this paper, and the other is well known report by the Imperial Earthquake Investigation Committee. As a result, the damage of RC buildings was clearly related with their building type and use, number of floors and distributed area. Detailed investigation on some damaged buildings revealed the situation of reinforced concrete buildings at that time, as well as the properties of damage investigation by a construction company. Microtremor observation and soil boring log collection were newly done at 53 sites of damaged buildings. Surface soil conditions obtained from H/V spectra of microtremor and drilling data were examined and shown to be related with reinforced concrete building damage. The difference of seriously damaged area of reinforced concrete buildings and wooden houses was observed which will be important aspect of seismic hazard distribution in the Tokyo city area.

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The properties of internal pressures induced by wind in buildings are very important for evaluating the wind loads of exterior materials and partition walls in those buildings. This paper describes the properties of internal pressure induced by wind in nominally sealed but leaky low-rise buildings with partition walls. The internal pressures induced by wind in the twin-room building models are numerically simulated by using the external pressures and leakage model of leakage paths of external walls and partition walls. Also, the internal pressures of twin-room building models are measured in a wind tunnel experiment with the models having apertures in their external walls and partition walls. It is shown that the maximum value and minimum value of the mean internal pressure coefficients induced by wind in the twin-room buildings depend on the ratio of leakage in the external walls and the partition walls.

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During the 2007 Noto-hanto Earthquake, the town of Anamizu experienced severe damage, though the town is located about 20 km away from the epicenter. More than 70 of wooden houses were completely collapsed in the area of 500 m square and the damage was remarkably concentrated in the zone of 100 m square. We measured micro-tremor at more than fifty locations and found that the area with collapsed houses has predominant frequency between 1.1 Hz and 3.0 Hz and the concentrated damage zone has about 2.0 Hz. Two layered irregular subsurface model was constructed by simulating H/V spectrum peak frequencies with frequency dependence of the particle motion of Rayleigh wave fundamental mode. The concentrated damage zone seems to lay on thick soft layer of 12 m to 15 m surrounded by shallower bedrock with thinner surface layers; the zone seems to locate at the mouth of a bay of about 200 m wide. The two dimensional FEM model with Ricker wave incidence reveals the constructive interference of reverberation and the Rayleigh waves. The ground motion during the main shock was evaluated by the 2-D FEM equivalent linear analysis with simulated incident waves and soil non-linearity of surface layers, which reveals about 10 % increase of response spectrum around 1 Hz.

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Short active faults observed on the ground surface have been supposed to indicate longer subsurface faults in the seismogenic layer. However, no concrete procedures have been proposed so far for modeling the subsurface faults for predicting strong ground motions. Hence, we surveyed several important research papers, and proposed a procedure for modeling the subsurface faults. Here, the seismic moment M₀ of 7.5×10²⁵ dyne•cm was assumed as the minimum size of the source for the case that any short active faults were observed on the surface. The modeling procedure was based on the asperity model, that was adopted by the Headquaters of Earthquake Research Promotion (2005) in Japan. Five main fault parameters of the area of the entire fault S, the averaged stress drop Δσ, the area of the asperities S_asp, the stress drop on the asperities Δσ_asp, and the short-period level A were determined by the two theoretical relationships and the three empirical relationships among the six main fault parameters including the seismic moment M₀.

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The site amplification factors in Niigata plain, Japan, are empirically estimated by the spectral inversion analysis from S-wave parts of strong motion data. The resultant characteristics of the site amplification are relative large in the frequency range of about 1.5-5 Hz, and decay significantly with the frequency increasing over about 5 Hz. In order to explain these features, we propose to consider random fluctuation in the modeling of deep S-wave velocity structure for site factor estimation. As a result, the site amplification in the frequency range higher than about 5Hz are filtered out by the effects of the velocity fluctuation similar to those observed in Niigata plain. We further demonstrate that the addition of the damping factor in subsurface modeling also has the same high-cut filtering effect on the site amplification factor estimation. We also discuss the relationship between the additional damping factor and the strength of random fluctuation.

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Response-controlled and linked structural system is suggested to over-track buildings as a system with the applicability. About the example that applied response-controlled and linked structural system to an over-track building, possession performance as the building was identified by earthquake response analysis. At the same time by analysis of the maximum earthquake prescribed in design standard for railway structure, the performance was inspected as the railway structure. By an examination in a station building, vibration characteristic of an over-track building was evaluated and inspected the effectiveness of the adopted system.

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Observations of earthquake ground motion due to aftershocks of the 2007 Chuuetsu-oki earthquake were conducted in Kashiwazaki city, Niigata prefecture, by installing 10 seismometers with different geological conditions for aiming at understanding local site amplification in the area. The site amplification shows large peaks around one second at the site in the central parts of the city. We also conducted microtremor array explorations at the observation sites. The shallow Vs-profiles were estimated from inversions of Rayleigh wave phase velocities obtained from array analysis of vertical microtremors. The amplifications of S-waves for the inverted profiles are similar to those from the aftershock ground motions. The average S-wave velocity for the top 30 meters of the S-wave profiles is calculated at each site. The average velocities at the sites with damage of wooden houses are less than 130 m/s.

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The number of seismically isolated buildings has been increasing after Hanshin-Awaji earthquake in Japan. One of the structural designs of recent seismic isolation is specialized by isolation of super high rise buildings. Many of these buildings employ sliding isolation bearings to further elongate its natural period of isolation layer compared to that of superstructure. Seismic isolation enhances the safety of building during earthquake. But the fatigue caused by deformation during strong wind must be checked, since building in Japan suffers from strong typhoons during its lifetime, especially if they are high rise buildings. The authors have conducted fatigue tests of sliding bearings especially for its rubber pad. Also, the authors have evaluated the wind levels and the duration for each wind level which the building experiences during its lifetime. By conducting wind response analyses, considering the fatigue test results and the wind excitations which the building experience during its lifetime, the evaluation method of fatigue is proposed and expected fatigue level using proposed method is presented.

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This paper presents an enhanced genetic algorithm with a randomized line search technique to improve the convergence and accuracy ratio. The presented technique is the simple one-dimensional search in which design variable axes are selected randomly as the search direction. The presented algorithms are applied to the discrete sectional optimization problems to achieve the minimum structural weight and the minimum structural cost of the 3-story and 5-story steel structural plane frames. The numerical results obtained by the presented algorithm are compared with those obtained by the conventional genetic algorithm to check the effectiveness.

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The purpose of this paper is to propose a rational design approach to the seismic retrofitting of an existing building connected with an adjacent newly-built outer frame by viscous dampers. The mass and stiffness of the existing building together with the mass of the outer frame are given. Then the stiffness of the outer frame and the damping coefficient of the connecting dampers are found so that the requirements on the maximum interstory drift of the existing building are satisfied. By introducing a response reduction contour map in terms of the stiffness ratio κ and the connecting-damper damping ratio h^R of the rigidly supported model, an approximate but effective design procedure is proposed. It is concluded that the proposed approach is an effective method for designing the outer frame and the connecting dampers.

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This paper discusses accuracy of a global damping model for approximate analysis of the structural system with viscoelastic damper. The model utilizes equivalent period and damping ratio of the system specifically determined at the resonant state, and, unlike the original system, it possesses neither frequency-dependency nor localized damping mechanism. By using different ground motion records, accurate time-history analyses are conducted using numerous multi-mass systems with the dampers, and the results compared to those using their global damping models. With some modifications depending on the damper type, the global damping model is found to produce reasonably accurate results, thereby warranting its extended use for a conventional response spectrum analysis or simplified time history analysis.

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Charpy impact test has been established as a convenient evaluation method for the toughness of steel materials. Since the Hyogo-ken Nanbu earthquake, even in the field of building structures, technical standards to prevent the brittle fracture of steel members have been introduced and the required value of the Charpy energy absorption has been standardized. However, the result of Charpy impact tests differ widely depending on the material properties. Therefore, it becomes important to clarify the correspondence between the difference of the result of Charpy tests and the ductility of real structures. In this investigation, using two materials which have different properties in terms of Charpy test, the full scale test on the structural behavior was carried out. Under the controlled temperature, the difference of the full scale test was minutely examined by comparing the difference of the Charpy energy transition curve of materials.

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The scheme of computational morphogenesis for the shell structures with free curved surface is proposed, where shape, distribution of thickness and topology can be simultaneously optimized. In the proposed scheme, distribution of thickness is discretized based on those values at each node, and Non Uniform Rational B-Spline (NURBS) is utilized by which the number of unknowns can be controlled while the high degree of freedom for expression of the shape of the curved surface and distribution of thickness are maintained. Moreover, the contour lines with respect to shell thickness over the shell surface are utilized by which topology of shell structures can be not only scraped but also grown up. By using this method, shell structure optimized with respect to not only shape and shell thickness but also topology can be obtained. The problem in question has been mathematically formulated as strain energy minimization problem of which coordinate of NURBS control point with respect to the shape of the curved surface and distribution of thickness are adopted as the design variables and numerical examples are presented where the effectiveness of the proposed scheme is investigated.

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The main objective of this study is to analyze a two-story wood structure consisting of shear wall with oil-damper and structural plywood wall using time history response analysis. It is important to evaluate the nonlinearity of support members for connecting damper and structural frame in wood structure. To evaluate the characteristic of support members, shear load tests were conducted. The feature for time history analysis is a point taken after the model of series coupling of nonlinear spring and nonlinear dashpot. First, Shear wall with oil-damper was conducted and it was confirmed that numerical model corresponded to the test result. Then time history analysis was conducted and test result and numerical model agreed well. Finally, seismic design value “Equivalent evaluation of shear wall strength” used in evaluating shear wall with dampers for seismic retrofit in wood structure was also confirmed using Incremental Dynamic Analysis.

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This study aimed to develop prefabrication techniques for building reinforced concrete structures using Mt. Pinatubo ejecta as concrete aggregates and propose houses that are strong against earthquakes. This paper first gives an overview of the structure and a test design of prefabricated houses. Then, an investigation of their seismic performances is described, which involved static loading tests of full-scale frame models of the structures. A model for elasto-plastic analysis that could reproduce the behaviors of the frames was also constructed and used to calculate their responses and limit strengths, with which the seismic performances were checked.

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A high-rise building system with reinforced concrete shear walls makes flexible planning possible, since the shear wall can bear most of seismic force and relieve the load of columns. Lateral and axial loading tests on the reinforced concrete shear wall with 120N/mm² compressive strength concrete had been conducted. The test results reveal that its structural performance is greatly affected by axial compression behavior of the local compression zone in the shear wall.
3D frame analysis is a valuable method to estimate the earthquake response of high-rise buildings. In this paper, 3D analytical models of the shear walls with ultra-high-strength concrete have been investigated, which can represent its compressive failure.

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This paper describes results of shaking table tests on precast prestressed concrete frames. The frame with bonded beams specimen and the frame with unbonded beam specimen were tested to observe and investigate their structural capacities including their ultimate state. Input wave were artificial one under 75Kine and actual measurement on Kobe earthquake at JR Takatori in final. The results of tests indicate that precast prestressed concrete frames had the high ductility and returnable capacities. The bond beam specimen was stronger than the unbonded one. The lateral displacement of all frames was mainly occurred at the connected potions between members. Pushover analysis can roughly simulate the test results. The model of skeleton curves was assumed as tri-linear calculated using the fiber model analysis.

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There are two cases of behavior of multistory frames after the vertical collapse of one story which occurs due to an event such as an explosion or an earthquake. One is where the collapse proceeds to a certain extent and then ceases and the other is where the collapse continuously progresses until all stories have completely collapsed. The collapse in the latter case is called progressive collapse which is an unstable phenomenon resulting from the gravity load frames. This study clarified the frame conditions which enable stories to resist progressive collapse through comparing the gravity potential energy released by the story collapse with the energy which columns absorb before they completely collapse due to the compressive load.

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This paper proposes design procedures that yielding of beams occurs before RHS-column to beam connections stiffened by exterior diaphragms yield. Cyclic loading tests of beam-column subassemblages for interior columns were conducted in order to verify the validity of the proposed design method, and elasto-plastic behaviors of beam-column subassemblages for exterior column or concrete filled tube column were investigated. The test results reveal that the design method is valid. Stiffness of beams with exterior diaphragms can be properly predicted by assuming that beams are connected rigidly to columns. Deformation capacities of specimens whose beams are connected to exterior diaphragms with high-strength bolts are substantially larger than that of the specimen that beam flanges and exterior diaphragms are welded.

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When the non-structural members such as folded-roof plate are directly jointed to the structural members, the non-structural members may be used as the eccentric bracings. This paper clarifies the effect of lateral and rotational restraint for continuously eccentric braces on buckling stress for H-shaped compression members. The elasto-plastic buckling stress is evaluated with the buckling curve for design codes using the modified equivalent slenderness ratio. Then the elastic buckling load with energy method is applied to the slenderness ratio. Finally, the relationship between the rigidity and strength of bracings is expressed as the approximation.

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This paper presents a new energy dissipation device for earthquake protection of structures. In the proposed device, the dissipation of seismic energy into structure is achieved through yielding of U-shaped steel dampers. The system is based on a quasi-linear motion mechanism and consequently bracing members are subjected to only tensile force. This can eliminate the brace-buckling problem. The stiffness and strength evaluations are performed for the steel frame with the proposed devices. Cyclic loading tests of the portal moment frames with the proposed device are conducted. Results and discussions are presented with emphasis on key features which affect energy dissipation capability. The lateral load and story drift angle relationships show that the proposed device provides stable and reasonably large energy dissipation capability. The effect of pre-tension applied to the bracing members is also examined through the brace axial strain and lateral load relationship.

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The effects of high temperature on the mechanical properties of 100N/mm² high strength concrete have been studied experimentally at various temperatures ranging from room temperature to 700°C. Test results indicated that transient strain accounts for a big rate to total strain, and the effect of transient strain of high strength concrete is bigger than that of moderate strength concrete. We tried to formulate transient strain on the basis of Anderberg's model and obtained transient strain coefficient k₂=5.56. Displacement constraint condition tests at elevated temperature were carried out and the constitutive model of high strength concrete was verified by thermal stress analysis. The results indicated that taking into account transient strain improved the analytical estimation of the variation in thermal stress of high strength concrete exposed to fire.

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Fire resistance of High strength reinforced concrete columns with specified design strength of 80N/mm² to 200N/mm² were conducted by loaded fire resistance tests. High strength concrete column without fiber showed explosive spalling and fire resisting period of columns were less than 2 hours. Incorporating polypropylene fiber to concrete of 150N/mm² or less was showned to be effective for preventing spalling of concrete and prolonging fire resisting period. For more than 180N/mm² columns, 0.33vol% of polypropylene fiber were not sufficient for preventing explosive spalling and incorporating both polypropylene and steel fiber enables to maintain 3 hours of fire resistive period.

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