Further shake table tests were conducted to examine the seismic performance of unit houses (prefabricated metal houses). A specimen comprising 4 unit-house units connected vertically and horizontally was subjected repeatedly in the long-side direction to the JMA Kobe record. The nonstructural, external wall panels increased the strength of the specimen twofold. The energy dissipated by repeated slipping of the slip-critical bolted connections equaled 88% of the total energy dissipated by the structural frame.

This research focuses on deterioration behaviors of the unloading stiffness obtained from loading tests of beam-to-column joints of composite beams and steel beams, and discusses the applicability of numerical analyses. The Ibarra-Medina-Krawinkler model expresses degradations of the stiffness and load capacity based on the hysteresis energy. By giving appropriate parameters, a stiffness deterioration behavior at the positive bending of the experiment was efficiently represented. The difference in hysteresis energy due to the presence or absence of stiffness deterioration reached about 20 % when the value positive bending stiffness dropped to about 80 %.

The March 11th, 2011 Tohoku earthquake and subsequent tsunami caused great damage over a large region of North-Eastern portion of Japan. The magnitude of the event was not predicted and thus found Japan unprepared, especially for the effects of the tsunami. This article is a summary of observation of damage and disruption based primarily on the information available within 3 months after the disaster. Also presented are the lessons that the authors believe have been learned and should be shared within the international community of earthquake disaster mitigation researchers and practitioners. The major issues discussed are the ground motion, tsunami, building damage, and post-event response. Recent research efforts in response to the disaster are also touched upon briefly. © Springer Science+Business Media Dordrecht 2014.

Two full-scale steel moment-resisting frames were constructed and tested at E-Defense to examine the performance of high-rise buildings subjected to long-period ground motions. Frame 1 adopted typical design and detailing from the 1970's employing both field- welded and shop-welded details for the moment frame connections. Frame 2 was identical to Frame 1 except that all connections were field-welded and upgraded using three strengthening methods. A number of connections in Frame 1 fractured during a simulated long- period motion. No damage was observed in Frame 2 until the same motion was repeated multiple times. The performance of field- welded connections in existing high-rise buildings and the effectiveness of upgrade methods are discussed.

The seismic capacity of beam-to-column connections in steel high-rise frames is a matter of concern, particularly when they are subjected to long-period ground motions. A previous full-scale shaking table test conducted at the E-Defense National Research Institute for Earth Science and Disaster Prevention in Japan disclosed cracks and fractures in such beam-to-column connections. This paper examines the effects of three types of beam-to-column connection retrofit: supplemental welds, wing plates, and a haunch. Quasi-static member tests and a series of shaking table tests applied to a full-scale specimen are conducted to quantify the respective performances of the retrofit schemes. The performance of a total of 28 connections tested by the member and shaking table tests is evaluated together with that of an additional 12 unretrofitted connections tested in the previous test. When the supplemental welds are applied only to the shear tab to the web, the connection fractures at the same instant as the connection without retrofit. The corresponding cumulative plastic rotation is not improved. When the supplement welds are further applied to the web-to-column connection, strain concentration at the bottom flange, primarily promoted by the presence of the RC floor slab, is significantly reduced, and the cumulative plastic rotation capacity is increased to eight times that of the connection without retrofit. For the wing plate connection and haunch connection, the critical section is moved from the beam end to the beam cross-section corresponding to the tip of the wing plates or haunch, resulting in an improvement of ductility by eight times that of the unretrofitted connection. Copyright (C) 2011 John Wiley & Sons, Ltd.

The performance of high-rise steel moment frame buildings constructed in the 1970’s is examined by using the E-Defense shake-table facility. Typical design and detailing in the 1970’s are incorporated in a four-story, steel moment frame specimen. The specimen is subjected to a series of response deformations representing a high-rise building. Long-period ground motions impose a substantial number of inelastic deformations, which eventually cause fracture in the beam-to-column connections.

The performance of high-rise steel moment frame buildings constructed in the 1970's is examined by using the E-Defense shake-table facility. Typical design and detailing in the 1970's are incorporated in a four-story, steel moment frame specimen. The specimen is subjected to a series of response deformations representing a high-rise building. Long-period ground motions impose a substantial number of inelastic deformations, which eventually cause fracture in the beam-to-column connections.

A series of E-Defense shaking table tests are conducted on a large-scale test specimen that represents a high-rise steel building. Two types of connections featuring the connection details commonly used in 1970s, in the early days of high-rise construction in Japan, are adopted: the field-welded connection consisting of welded unreinforced flanges and a bolted web type, and the shop-welded connection in which the flanges and web are all-welded to the column flange in the shop. To examine the seismic capacity of a total of 24 beam-to-column connections of the specimen, particularly when it is subjected to long-period ground motion characterized not so much by large amplitude as by very many cycles of repeated loading, the test specimen is shaken repeatedly until the connections fractured. The test results indicate that a few of the field-welded connections fractured from the bottom flange weld boundary in a relatively small cumulative rotation primarily due to the difficulties in ensuring the welding and inspection performance in the actual field welding. The shop-welded connections are able to sustain many cycles of plastic rotation, with an averaged cumulative plastic rotation of 0.86 rad. Two shop-welded connections exhibit ductile fractures but only after experiencing many cycles. The presence of RC floor slabs promotes the strain concentration at the toe of the weld access hole in the bottom flange by at least twice compared with the case without the slab, which had resulted in a decrease in the cumulative plastic rotation by about 50%. Copyright (C) 2010 John Wiley & Sons, Ltd.

The seismic capacity of beam-to-column connections in steel high-rise frames is a matter of concern, particularly when they are subjected to long-period ground motions. A previous full-scale shaking table test conducted at E-Defense disclosed cracks and fractures in such beam-to-column connections. This paper examines the effects of three types of beam-to-column connection retrofit: supplemental welds, wing plates, and a haunch. The performance of a total of twenty-eight connections tested by the shaking table tests is evaluated. When the supplement welds are further applied to the web-to-column connection, the cumulative plastic rotation capacity is increased to eight times that of the connection without retrofit. For the wing plate and haunch connections, the critical section is moved from the beam end to the beam cross-section corresponding to the tip of the wing plates or the haunch, resulting in significant improvement of ductility by eight times that of the un-retrofitted connection.

When subjected to long period ground motions, high-rise buildings would sustain large cumulative inelastic deformations. Beam-to-column connections with RC floor slab are tested to examine the existing performance and effect of seismic retrofit of existing high-rise buildings. Four field welded beam-to-column connections are prepared in reference to the details of high-rise buildings built in 1960s-1970s. Three types of retrofit are adopted for the beam ends, namely welding along the shear plate, attachment of wing plate haunches, and attachment of a vertical haunch. For the unretrofitted connection, presence of a floor slab is attributed to the fracture in the bottom flange. The three retrofitted connections showed three different failure modes. A plastic theory is applied to interpret the resisting mechanisms, indicating reasonable correlation with the corresponding test results.

Quantitative information on the seismic performance of nonstructural components is scarce. Among various nonstructural components, damage to interior drywall partitions affects significantly to the economic loss. Three full-scale drywall partitions, i.e., a standard plane partition, a partition with a door, and a partition with an orthogonal wall, are tested to observe the initiation and evolution of damage in cyclic loading conditions up to a drift angle of 0.1 rad. The plane drywall partition remains undamaged up to 0.01rad, while the partition with a door or the partition with an orthogonal wall sustained damage at a smaller drift angle because of local constraint. The partitions exhibit some lateral resistance, which is provided primarily by the bearing between the gypsum board and surrounding columns. The progress of damage is presented in terms of the ratio of the repair to initial cost. The ratio reaches about 1.0 and 2.0 for a drift angle of 0.04 rad and 0.06 rad, respectively.

As the first part of non-structural component test series, interior drywall partitions are selected for an experimental program. This test series will cover non-structural components that are significant in the economic losses in buildings subjected to seismic loading, namely interior drywall partitions, exterior cladding and window glasses, and ceilings. Four full-scale drywall partitions with light-gage steel stud framing were tested to observe damage in cyclic loading conditions. Effects of a door and an intersecting wall on the behaviour of drywall partition are studied. Damage was concentrated to perimeter regions where gypsum boards made contacts with ceiling, floor, or columns. Dynamic loading did not amplify the damage on a drywall partition over the damage observed from the quasi-static test. Damage-repair cost relationships show that the repair cost reaches almost the initial cost under 2% radian interstorey drift. Copyright (C) 2006 John Wiley & Sons, Ltd.

This paper presents an experimental study on a steel moment frame with reinforced concrete (RC) floor slab that was subjected to horizontal cyclic loading leading to very large deformations. The primary objective of this test was to examine the interaction (composite action) between the steel beam and the RC floor slab. The steel beam moment capacity increased about 1.5 times in positive bending with the presence of the RC floor slab. During small beam rotations of 0.002-0.003 rad, the beam strength increased 1.2-1.4 times in negative loading, but composite action did not affect the negative beam moment capacity for larger rotations. The effective width estimated from the slab compressive force approximately equals the column width. Fracture at the bottom flange was notable due to the presence of the slab in the composite beam. Complete separation of the beam-to-column connections was not achieved even at a beam rotation of 0.13 rad, under which the composite connections still possessed bending resistance equal to about 10% of the maximum bending capacity when sustaining positive bending.

Interaction between the external wall cladding and the seismic load resisting frame was examined in a full-scale cyclic loading test of a three-storey steel building structure. The building specimen had Autoclaved Lightweight Concrete (ALC, also designated as Autoclaved Aerated Concrete) panels installed and anchored to the structural frame as external wall cladding, using a standard Japanese method developed following the 1995 Kobe earthquake. ALC panelling is among the most widely used material for claddings in Japan. In the test, the ALC panel cladding contributed little to the stiffness and strength of the overall structure, even under a very large storey drift of 0.04 rad. No visible damage was noted in the ALC panels other than minor cracks and spalling of the bottom of the panels In the first storey. Consequently, in a Japanese steel building with properly installed ALC panel cladding, the structural frame is likely to be little affected by its cladding, and the ALC panels are capable of accommodating the maximum storey drift generally considered in structural design without sustaining discernible damage. Copyright (C) 2006 John Wiley & Sons, Ltd.

The bending moment resistance of the column bases decreased seriously during overall drift angle 1/15rad loading, because of the fracture of the anchor bolts in tension side and the crash of concrete placed under the base plates in compression side. The inflection point of first story columns moved to lower by column base moment resistance decreasing and increased the bending moment at the first story column top. In result, local buckling occurred at the first story column top and formulated the first-story collapse mechanism. The first story shear decreased significantly with the increase in story drift angle from 1/20 to 1/8rad, while the second story was unloaded.

A test on a full-scale model of a three-storey steel moment frame was conducted, with the objectives of acquiring real information about the damage and serious strength deterioration of a steel moment frame under cyclic loading, studying the interaction between the structural frame and non-structural elements, and examining the capacity of numerical analyses commonly used in seismic design to trace the real cyclic behaviour. The outline of the test structure and test program is presented, results on the overall behaviour are given, and correlation between the experimental results and the results of pre-test and post-test numerical analyses is discussed. Pushover analyses conducted prior to the test predicted the elastic stiffness and yield strength very reasonably. With proper adjustment of strain hardening after yielding and composite action, numerical analyses were able to accurately duplicate the cyclic behaviour of the test structure up to a drift angle of 1/25. The analyses could not trace the cyclic behaviour involving larger drifts in which serious strength deterioration occurred due to fracture of beams and anchor bolts and progress of column local buckling. Copyright (c) 2005 John Wiley & Sons, Ltd.

The writers conducted a full-scale loading test on a steel moment frame with RC floor slab. The primary objective of this test was to examine the interaction between the steel beam and RC floor slab (composite action). The steel beam strength for positive bending increased about 1.5 times by the presence of RC floor slab. RC floor slab did not affect the beam strength in negative bending. During small beam rotations of 0.002 to 0.003rad however, the beam strength increased 1.2 to 1.4 times even in negative loading. The effective width in reference to the concrete cylinder strength approximately equals the column width, which is much smaller than the effective width stipulated by the AIJ composite code.

This paper presents detailed results on damage sustained by beams of a full-scale three story steel moment frame subjected to large cyclic loading. Intentional connection defects (misalignment and insufficient fusion of welds) were embedded at few beam-to-column connections. Misalignment by 3mm between the diaphragm plate and beam flange caused brittle fracture at a beam rotation of 1/27 rad. Otherwise, effects of small defects on the overall behavior remained minimal. Composite action was observed for the strain distribution along the beam depth and for the increase in bending strength during the positive loading. Effects of composite action, given as the difference between the positive and negative bending moments for the same rotation, increased for larger story drifts. The degree of increase, however, was not as large as that estimated by commonly used effective-width approaches.

This paper presents a study on the calibration of numerical inelastic analyses for the capacity of estimating the elastic stiffness and yield strength of multi-story steel moment frames and of tracing inelastic cyclic behavior of such frames. To this end, a set of test results obtained from a full-scale cyclic loading test applied to a three-story, two span by one span steel moment frame were used as the reference. Pushover analyses using nominal material strength were able to estimate the frame's elastic stiffness and yield strength very reasonably, with the degree of errors not greater than 5%. Analyses for cyclic loading to a drfit angle of 1/25 rad were also very accurate (with errors not greater than 4%) if appropriate values were adopted for strain hardening of individual columns, column-bases, panel-zones, and beams and for increase of strength by floor composite action. The fish-bone (generic frame) model traced the experimental behavior nearly as accurately as the original frame model.

The writers conducted a full-scale loading test on a three-story steel building structure. To examine the interaction between the structural svstem and exterior finishes (ALC panel) was one of the primary objectives of the project. The ALC panel's connection detail adopted in his study is typical of the post-Kobe Japanese construction. The test showed little damage to the ALC panels. The panels did not affect at all the structural behavior up to the 1/25rad amplitude, and no visible cracks were observed in the panels except for minor cracks and spalling of concrete at the bottom of the panels in the first story.

鋼構造建築物の倒壊過程を実験的に解明する研究目的に沿って、国立研究開発法人防災科学技術研究所の大型耐震実験施設で、2020年11月から12月にかけて、縮尺1/2のパイロット試験体による振動台実験を実施した。同研究所の兵庫耐震工学研究センターで、2020年12月に実施された日米共同実験に参加し、次世代型鋼構造システムを開発する研究を推進した。大型耐震実験施設で、2021年12月に、縮尺1/3の4層ラーメン構造の倒壊実験を実施した。一方で、倒壊に至る鋼構造の非線形・動的挙動を追跡するコンピュータ解析技術を確立する研究目的に沿って、数値モデル化技術を種々検討してきた。一連の研究活動で得られた成果は、下記のとおりである。（１）倒壊実験によって、柱や梁が降伏し破断する過程と、損傷と破壊が架構全体に伝播する状況に関する実データを収録できた。（２）複数の実験から得た、鋼構造架構の非線形動的応答に関する実データを、既往の大規模振動台実験のデータと合わせて、数値解析技術の検証を進めてきた。特に、破断を模擬するための現状のモデル化手法では、既往の重層架構実験で観察された、部材破断後の部材力再分配を正しく再現できないことを突き止め、今後の課題を特定した。減衰モデルの選択によって、架構の応答変位や応答加速度が異なることに注目し、定量的な検討を進めた。（３）部材破断の再現方法を含めて、ブレース付鋼構造架構の解析手法に関する知見を蓄積し、現状のブレース付鋼構造架構が保有する耐震性能を検証した。

本提案では，即時応急危険度判定として，地震被災建物の非構造材の動作に関する計測値分析と，屋内外のビデオ映像に基づく外観損傷や部材変形の画像解析を統合し，構造体の安全性はもとより建物機能の健全性を判定する方法を開発することを目標としている。さらに，判定結果を速やかに周囲に伝達することで，人間避難行動を適切に誘導する判定情報伝達技術の開発までを射程とする。本年度も引き続き，鋼構造架構を準備し，間仕切壁，カーテンウォールの加振実験を実施した。部材角を評価するGyro，表示のLEDの適用性について検証した。判定基準整備の一環として，確率論的性能評価の適用性について検討を重ねた。

In order to maintain and continue normal living and economic activities in our society, preparing for the future large-scale earthquake event, it is necessary to judge the performance of the infrastructures after the earthquake as a matter of course to improve the earthquake resistance before the earthquake. For this reason, many investigations have been conducted on structural health monitoring. Here, we have researched a system that estimates the structural characteristics of a building after the earthquake by capturing the response of non-structural element installed in the building with MEMS(micro-electro-mechanical systems) sensor. In this research, we have finished the basic investigation for practical use.

The primary objective of the research was to obtain experimental data on failure of steel components and to advance the technology to numerically simulate the seismic response of steel building structures. The research was planned towards the larger goal of establishing a methodology to assess whether a steel building can safely survive, or maintain usable, after an extremely large earthquake beyond the consideration of building codes. Dynamic loading test of beam-to-column connections was conducted to examine how seismic performance may be affected by connection type and presence of composite floor slab. Numerical modeling techniques were examined to capture the gradual degradation of steel components due to start and propagation of ductile fracture. The model was used to demonstrate that good agreement can be obtained between simulated and experimental behavior of multi-story steel building systems. An additional study was conducted on damping models suited for nonlinear analysis.

A method of substructure test was developed by using a shaking table facility. Deformation time histories occurring in prototype buildings were applied to the substructure specimen equivalent to their critical portions. The force-deformation hysteresis was evaluated in the large deformation level significantly exceeding design limit, and compared with a promising numerical model, Krawinkler model. This model was developed in Stanford University, and is now recommended in the newest high-rise building design guideline of the United States. The ultimate energy capacity and other main parameters were tuned according to the test results. The numerical models, which represented substructure test results, were incorporated in the model of a full-scale frame test structure. The adopted method of static cyclic loading frame analysis indicated a new design procedure based on a reasonable performance assessment format.

For beam-to-column connection of the steel building, the gradual increase amplitude cyclic loading experiment which assumed loading speed (period 1Hz and 0.01Hz) were carried out. This experiment is fundamental researches for the performance evaluation technique construction that can evaluate the influence that the fracture property of the member end and the yield mechanism of the frame give to the ultimate state of the building. The conclusions obtained from this experiment are (1) The difference in loading speed produced differences of some behavior.(2) In the dynamic loading, beam-to-column connection fracture occur in comparison with static loading earlier, and plastic deformation capacity was inferior. For sliding in the high-strength bolt friction joint, the possibility that it hastened the crack spread started from the welding defect is thought about.

Japan and many regions in the world keep suffering from large earthquakes, and building collapse is considered to be most responsible for both the human and material losses. Advancement of building technologies for better collapse prevention is a critical societal need. This study proposes a new system in which the base of the super-structure is detached from the foundation, by which shear forces exerted onto the super-structure can be capped to a specified level. A series of dynamic loading test indicates that placing carbon graphite on the surface of foundation RC/mortar beam is found to ensure a friction coefficient of about 0.2 despite the number of sliding cycles. Theoretical equations are formulated to represent the sliding structure, and extensive time-history analyses are implemented for sliding structures subjected to pulse-type ground motions. The results verified that the maximum shear force applied to the super-structure is approximately twice the friction coefficient.

Dynamic loading test is useful for the advancement of earthquake engineering. Due to high cost among others, dynamic loading systems are commonly limited in size. Needs for dynamic loading test, however, increases in conjunction with the development of various damping devices used for mitigation of earthquake disasters. This study develops methods that increase the power, i.e., the displacement, velocity, and frequency capacities, of shaking tables, by the addition of extra segments that are connected to the shaking table. A displacement enhancing segment is developed by a combination of linear roller sliders and ballast, while a frequency enhancing segment is developed by the production of continuous collision between two spring-mass systems. To ensure accurate response on the segment, various control algorithms are developed. Effectiveness of the proposed system is examined for the behavior of medical appliances installed in a base-isolated medical facility.

Examined in this research are the mechanism of amplification for the acceleration responseof medical appliances relative to the input acceleration and their effect onto the performance of the appliances. The appliances would sustain significant jumping and according damage when the maximum accelerations exceed 4g. Exceptions are those with flexible elements in the vertical direction, in which they would experience significant motion such as jumping even for the acceleration ranging 1 to 2g. A generic 3DOF model is developed to quantify the degree of acceleration amplification from the ground to the floor of the superstructure.