中村 友紀子

<p>梁間方向が9mであるのに対し，桁行方向が最大で84mと非常に大きい辺長比を持つ建物を対象として，強震時及び常時微動の振動観測が長期間にわたって行われた．得られた記録に対して並進振動及び捩れ振動の成分に注目してフーリエ変換を用いた解析を行い，推定される卓越振動数が季節によって変動していることを確認した．さらに，コヒーレンスが低下する現象についても検討を行い，振動性状の詳細について考察を行った．また，比較的短時間の気温変化であっても卓越振動数が変化する例が見られた．</p>

家具の転倒が人体に及ぼす影響について、2期に亘る実験を通して検証を行った。第1期の実験では、種々の地震動とスィープ加振により、家具が転倒または移動する状況の把握と、人体ダミー人形への影響（頭部加速度と胸部変形量）の測定を行ったが、大きくばらつく結果を得た。そこで第2期の実験では、床応答を度外視し、転倒時のパラメータを振ってダミー人形への入力を詳細に計測し、人体への影響がどのような条件で大きくなるのかを明らかにした。

The school building suffered from a great deal of damage during the 2007 Chuetsu-Oki Earthquake. The previous study revealed that the anticipated design failure modes of most of the columns of the building were flexure although most of them actually failed in shear. In order to study the reason a parametric study was also conducted and it was concluded that the diagonal crack generated from cut off point caused shear failure in these columns. In this study static loading tests were conducted varying the length of cut off bars and the presence of spandrel walls. Main conclusions were as follows; (1)The deformation capacity of a column with cut off bars degraded tremendously on condition that the yielding hinge location was cut off point and the inclination angle of diagonal cracks generated from the cut off point was approximately 50 degree. (2)The effect of presence of spandrel walls on deformation capacities was small.

The Niigata-ken Chuetsu Earthquake in 2004 and The Niigata-ken Chuetsu-oki Earthquake caused damage to R/C School Buildings. Relation of destructive power indices of observed strong motions to seismic performance index of reinforced concrete school buildings which was evaluated according to Standard for Evaluation of Seismic Capacity of Existing reinforced Concrete Buildings and a residual seismic capacity ratio index R which corresponds to building damage were examined. PGA, Japanese Metheorological Agency seismic intensity scale, PGV, Spectrum Intensity and Average elastic velocity response in a period range of 1 to 2 seconds with a damping factor of 0.05 were used as the destructive power indices of strong motions.

The objective building is a R/C school building constructed in 1963 and it suffered during the both Chuetsu and Chuetsu Oki Earthquake. As for the damage level, the both first and second stories were slightly damaged by Chuetsu Earthquake and they were partially damaged by the Chuetsu Oki Earthquake. The data of concrete strength and the reinforcing arrangement could be investigated directly from the building. This paper reports on the damage of the building during both earthquakes firstly. Secondly to explain the property of both earthquakes more in detail, it also reports on the result of the seismic response analysis. Finally, to examine the effects of parameters that are used in the process of the evaluation of seismic performances of buildings on the evaluated results, the collapse modes of the columns are examined by varying each parameter such as material strength, reinforcing arrangement, and so on.

This paper proposes new masonry walls using ductile interlocking blocks for retrofitting existing buildings. The presented walls are capable of resisting out-of-plane loads by the interlocking mechanism between blocks. Three 3/10 scale reinforced concrete frames were prepared, and two of them were retrofitted by the walls. Quasi-static loading tests of the specimens were carried out in the in-plane and out-of-plane directions, to compare their seismic performance. Installing the block walls, the strength of retrofitted specimens increased but ductility decreased. Moreover, one of them not only supported axial loads but also exhibited a frictional lateral resistance after failure of the columns.

耐震診断の結果を指標値とし,内法高さの操作による靭性指標の操作,強度指標・初期剛性の操作というパラメトリックな方法を用いて,Is値を一定に揃えた複数の方法による耐震補強の想定を行なった。その補強方法を用いた建築物を対象として,近年観測された複数の地震波を用いて,入力倍率を変更するなど,複数の地震応答解析を行なった。解析の結果,対象とした建築物の場合及び用いた地震動においては,Is値を0.70に揃える際に靭性型の補強を用いた場合には,地震動によっては残留変形が終局強度時変形角を越えた事から,同じIs値を満たす補強としても靭性型の補強と強度型の補強では使用継続性に差が出た。

2004年新潟県中越地震によって被災したRC造学校建物のうち被災の程度がわかる耐震性能残存率Rや耐震診断による構造耐震指標Is値の判明している建物を対象として,地震動の破壊力指標との関係について考察した。地震動の各指標は,強震記録の観測地点間で線形補間することでそれぞれの学校建設地の指標とした。地震動の破壊力指標としては,気象庁計測震度・最大加速度・最大速度・スペクトル強度・i-2秒速度応答を用いた。各指標とも大きくなるほど耐震性能残存率Rが小さくなる,すなわち大きな被害を受けていること,また構造耐震指標ISが構造耐震判定指標ISOを満たさない建物と,その他の建物では被害程度に差が生じていることを示した。

Objectives of this study were to propose evaluating method of axial load carrying capacities of R/C columns after shear failure using experimental data reported in the previous paper. For this purpose two criteria were examined, i.e. Mohr-Coulomb criterion and slip criterion between shear crack surfaces considering friction. Effects of confinement given by various hoop reinforcing details were specially paid attention. Two assumptions were used, i.e. i)the cohesive stress was degraded due to damage of core concrete and ii)confining stress by hoop reinforcement was degraded due to damage of reinforcement depending on the details. Finally evaluating equations of maximum deflection angles of shear failing columns experienced before losing their axial load carrying capacities were propose according to two assumptions mentioned above.

Standard for evaluating method of seismic performances of existing R/C buildings revised in 2001 showed evaluating methods of residual axial load capacity and axial load capacity, which had dramatic effects on seismic performance indexes. In this study the feasibility of this method was discussed using experimental data. For this purpose static loading tests of R/C columns were conducted. Main variable was loading methods; i.e. monotonic eccentric axial loading, eccentric axial loading under constant lateral drift and normal reversed lateral loading under constant axial load. An evaluating method of residual axial load capacity was proposed and compared with the standard.

コンクリートブロック塀は,単体では確認申請を行わずに建築できることもあり基準に適合しないものも多く,過去の地震ではブロック塀の倒壊によって人的被害も報告されている。耐震安全性向上策開発の基礎的検討として,新潟市における実態調査行った結果,控え壁を必要としない補強方法の必要性が明らかとなった。また,ブロックを用いた面外方向加力実験を実施し,手締めによる軸拘束によって崩壊防止策への可能性を示した。

面外方向への倒壊防止を意図した形状の靭性ブロックを組積するだけの簡便なRC造建物の耐震補強方法を提案し,組積造壁増設による補強効果,破壊機構の変化を明らかにするため,静的加力実験を行った。その結果,組積造壁の増設が架構の耐力を大きく向上させること,柱のせん断破壊後も組積造壁が柱に代わって軸力を負担すること,柱のせん断破壊を境に組積造壁が摩擦抵抗機構を発現することなどを確認した。

2004 年10 月23 日に発生した新潟県中越地震では、数多くの観測点で震度6 弱以上、特に川口町川口では計測震度導入以来初めて震度7 を記録し、地震動の性質と建物被害の関係を検討するための貴重な強震記録が得られた。そこで、波形が回収された観測点の周辺を対象として建物被害を中心とした被害調査を行った。調査の結果、川口町震度計、JMA 小千谷、K-NET 小千谷周辺で大破・全壊建物が確認されたが、その他の観測点周辺では大きな被害は見られなかった。そこで、回収された波形を用いて強震動の性質と建物被害との対応性について検討した。その結果、今回の地震で発生した地震動の多くは、0.5 秒以下の極短周期が卓越し、計測震度や地動最大加速度は大きな値となるが、建物の大きな被害を引き起こす性質のものではないことがわかった。一方、川口町震度計で観測された地震動は大きな1-2 秒応答を記録しており、それが大きな被害に繋がったと考えられる。

This study reports on the summary of damage of a four-story reinforced concrete building during the 2004 Mid Niigata Prefecture Earthquake and the results of evaluated seismic performance calculated according to currently used standard in Japan. This building is located at the center of Tokamachi city (seisimic intensity 6+) and was built in 1972. Some columns located in a half of the building failed in shear severely and the remaining seismic performance was found to be 62% of the original structure. This is supposed to be caused by rotational vibration generated by eccentrically located reinforced concrete and block walls.

This paper mainly discusses seismic performances of specially designed unreinforced masonry (URM) structures. Firstly, lateral force resisting mechanisms of masonry in filled frames were introduced through test results of concrete block in filled reinforced concrete frames with and without a door opening. Based on major findings from the tests, a method to enhance seismic performances of URM structures using interlocking masonry units was proposed. Two new URM walls consisting of brittle and ductile interlocking masonry units were tested and their performances were compared with that of a conventional one. Seismic performances of URM walls could be effectively improved by interlocking masonry units.

We investigated the 2004 Niigata-Chuetsu earthquake, where we have both strong ground motion records and building damage data, examining correlation between various indices of seismic destructive power and building damage. We confirmed that the average elastic velocity response in the period range of 1 to 2s with a damping factor of 0.05 which one of the authors proposed as an optimum destructive power index of strong ground motion for predicting building damage has close correlation with actual damage to buildings also in the case of the 2004 Niigata-Chuetsu earthquake. The period range is based on the equivalent periods that are calculated for buildings with typical elastic periods considering inelastic elongation. A vulnerability function of wooden houses for same seismic intensity in the case of the 2004 Niigata-Chuetsu earthquake was smaller compared to that in the case of previous earthquake, such as the 1995 Hyogoken-Nanbu earthquake.

Objectives of this study were to examine axial load carrying capacities of R/C columns after shear failure. For this purpose static loading tests of R/C columns were conducted. Confinement of hoop reinforcement to core concrete was one of the most important effects to be discussed so different hoop reinforcement details were studied, i.e. welded hoop for good confinement type, hoop with 135 deg hook for normal confinement type and hoop with 90 deg hook for poor confinement. Using these specimens centrical axial loading test to examine the basic confining effects and lateral loading test under constant axial load to examine the axial load carrying capacity were conducted.

高靱性セメント複合材料により作製したインターロッキング型組積ユニットを用い,これらを積み上げるだけの簡便な方法により組積壁を増設し,強度の上昇だけでなく靱性に富む耐震補強方法を提案した。本研究では増設壁のみを対象に静的破壊実験を実施し,増設壁部分の諸性能について検討した。その結果,靭性組積ユニットを用いた組積壁は壁面全域のユニットが一体となって水平力に抵抗する固有の性状,更に終局域であってもほとんど耐力低下を起こさない優れた変形性能を示したことから,本構法による耐震補強の実現可能性が確認された。

強震観測点周りの建物被害を調査し, 観測された強震記録と被災度の関係について検討した。震度の大きさの割りに被害を引き起こさない, 0.5秒以下の短周期が卓越した地震動が多かったが, 川口町の記録は1-2秒が卓越した非常に破壊力のある地震動で大きな被害を引き起こした。また木造に比べ, 鉄筋コンクリート造建物の被害は全体に小さかった。

2003年宮城県北部の地震では局所的に大きな被害が発生した。本論で取り上げる学校建物は,平野と丘陵地との境界に建てられている。RC造校舎は1971年以前と以後の設計の2棟があり,共に一部の柱や壁にせん断ひび割れが生じて損傷度II～IVと判定された。耐震診断の結果は2棟で異なるものとなったが,強度指標は同程度であることが2棟の被害程度が近いものとなった理由と考えられた。また,隣接する役場では,強震記録が観測されている。この地震動を用いて応答解析を行い実際の被害レベルと比較した。

本報告では,せん断破壊するRC造柱の地震時の軸力伝達能力喪失のメカニズムに及ぼす載荷履歴の影響を実験的に検討した結果を報告する。試験体は帯筋間隔を変えた2シリーズを作成し,それぞれのシリーズで中心軸圧縮実験を各1体,一方向載荷実験,繰り返し載荷実験を作用軸力を変えて各2体ずつ,計10体の試験体の実験を行った。

We investigated the 1994 Northridge, California, earthquake, where we have both strong ground motion records and building damage date, examining correlation between various indices of seismic destructive power and building damage. We used correlation analyses, maximum likelihood method and correlation analyses considering the number of buildings ground strong ground motion observation points, We confirmed that the average elastic velocity response in the period range of 1 to 2 s with a damping factor of 0.05 which one of the authors proposed as an ontimum destructive power index of strong ground motion for predicting building damage can be used in the case of buildings in California, USA The period range is based on the equivalent periods that are calculated for buildings with typical elastic periods considering inelastic elongation.

帯筋のフックの配筋詳細が異なる2シリーズのRC造柱試験体を各5体ずつ,計10体を作成し,中心圧縮,一定変位下,曲げせん断加力を行い,せん断破壊した後の軸力負担能力の評価実験を行った。さらに,帯筋の効果を直接的に評価する方法を検討した。帯筋フックの加工法は,90度で余長8dのものと135度で余長6dのものを対象とした。

RC造偏在戸型有開口耐震壁には開口の偏在により独立柱が存在する。耐震壁が正負交番載荷を受ける場合、この独立柱には高変動軸力が生じる。本研究では既報で報告したRC造偏在戸型有開口耐震壁の独立柱をとりだして静加力実験を行った。その結果、主筋の座屈の影響により、引張力を与えた試験体の方が最小軸力が0の試験体より早期に耐力低下が生じており、80%耐力低下点として定義した靭性限界点も小さかったことが分かった。ただし、全主筋を引張降伏させるかどうかは軸力負担能力(軸力喪失点の変形)には影響しなかった。この結果は偏在有開口耐震壁の独立柱のモデル化に役立つ。

1995年兵庫県南部地震を契機に耐震改修促進法が制定され、全国各地で公共建物の耐震診断・耐震改修が行われている。新潟県においても公立学校建築物の耐震診断が行われており、耐震診断が行われたもののうち耐震判定指標に満たない場合には耐震補強計画、補強を行っている。本報告では、新潟県での学校建築物の耐震性能の分析を行った。また、新潟県の学校建物のIs値頻度分布を推定し、被害率を算定した。耐震補強を進めることによって被害率がどのように変化するのか検討を行った。

A method is presented to formulate expected values of elastic time-history responses by assuming the phase differences spectrum in the Fourier transform of earthquake waves as a normal probability curve. A fair correlation was observed between the standard deviation of the phase differences spectrum of the motion and the expected value of time-history response based on the formula. The effects of viscous damping and fundamental period of the system on the deviation of expected value of time-history responses are investigated. The expected value of time-history response can be approximated from the characteristics of the earthquake waves, which may be used for the estimation of maximum displacement responses.

The objectives of this study were to examine deformation capacities of cantilever shear walls with openings experimentally and to evaluate the design equation (truss-arch analogous model), which had been developed to estimate the shear strength of shear walls with openings, for the estimation of the deformation capacities of cantilever shear walls with openings. Six reinforced concrete cantilever shear wall specimens with openings, which were designed to fail in flexure, had been tested already under static reversal load. In this paper test results of another two wall specimens with eccentric door openings were reported. Variables were the level of axial load and the hoop reinforcement of first floor columns, which were called isolated column in this study.

Expected value of time-history response can be formulated by assuming the phase differences spectrum in Fourier transform of earthquake waves as a normal probability curve. The effect of damping on the response spectrum can be obtained based on the formula. The ratio of maximum displacement to previous peak displacement during nonlinear response can also be calculated theoretically, which may be used for estimation. Both theoretical values were compared with those calculated from the responses to earthquake motions, from which a fair correlation was observed, especially in relation to the duration of earthquake motions.

A method of estimating inelastic displacement responses of single-degree-of-freedom system with a hysteresis rule of reinforced concrete structures was presented based on energy input characteristics of earthquake motions. Effective instantaneous energy was defined as input energy during one-fourth of the equivalent fundamental period of the system. The calculated inelastic responses could fairly be estimated from the effective instantaneous energy input spectra and the energy dissipation capacity of the system. The maximum displacements estimated from accerograms are correlated to the damage ratio to reinforced concrete buildings during the 1995 Hyogoken-nanbu earthquake.

A method of estimating inelastic displacement responses of single-degree-of-freedom system with a hysteresis rule of reinforced concrete structures was presented based on energy input characteristics of earthquake motions. Effective instantaneous energy was defined as input energy during the equivalent fundamental period of the system. The calculated inelastic responses could fairly be estimated from the effective energy input rate spectra and the energy dissipation capacity of the system. The instantaneous energy spectra could roughly be related to the spectra of time-averaged input energy defined as total energy divided by the effective duration of motions. Effects of damping characteristics on the instantaneous energy spectra and velocity response spectra were investigated, which were also found to be dependable on the duration of earthquake motions.

RC構造物の耐震設計における限界状態を最大応答変形で定義するためには、地震動、構造物のパラメーターと最大応答変形の関係を一般的にあきらかにする必要がある。塑性応答変形に有効な地震動のパラメーターとしてエネルギー人力速度スペクトルを定義し最大応答値を推定する方法を示した。また、総エネルギー入力、継続時間との関係も検討した。