This paper deals with abrasion damage to roofing materials caused by sliding snow on sloped roofs in a region receiving heavy snow. We tested abrasion of coated metal sheets due to sliding snow. From the test results, it became clear that three factors, namely the ratio of clay dust in roof snow, the snow load, and the snow sliding velocity, exert great influence on the abrasion. We calculated the number of times snow slid off the roof eaves for the purpose of estimating the degree of abrasion after the lapse of a certain number of years. The calculation was based on meteorological data as well as on observations of snow sliding off test roofs. From the facts described above, we obtained an equation for estimating abrasion of roofing materials of sloped roofs.

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The aim of this investigation was to study the vapour permeability of the out- side insulation wall in cold district. First, we examined the vapour permeability of insulations, exterior materials and paints at low temperature. Second, we examine the vapour permeability of the outside insulation wall by drying the concrete wall under experimental conditions. From the result of this investigation, we understood the vapour permeability of the outside insulation wall. The drying of concrete is mainly dependent on the insulation resistance of vapour permeability and outside temperature. The amount of humidity in the exterior materials was mainly dependent on the resistance of vapour permeability of exterior materials and paints. It was considered that the damage of paints related to the condition of painting at the site.

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1.序 重要構造物への航空機落下に対する安全設計に際しては、まず構造物への落下確率が評価される。そしてこれが許容値より小さければ航空機落下は設計対象から除外される。さもなければ適切な対応がなされる。Fig.1に航空機落下に対するリスクアナリシスのフローを示す。本論ではこのフローのうち、航空機落下確率評価法の研究例をレビューし、その中で、レーストラックパターン飛行に対する落下分布関数の改良を提案する。ここに、落下分布関数は飛行不能状態になった位置から見た地表各位置の、単位面積あるいは単位長さへの落下密度を表している。本論文ではさらに、フリー飛行領域からのプラントヘの落下確率評価法を提案する。これらの落下分布関数に対し感度解析を実施する。2.各飛行パターンに対する落下確率評価式 2.1.飛行場への離着陸 John M.Vallance[1]は1964年から1968年までの5年間における米国の801件の航空機事故を調査し、その内から飛行場への離着陸に関係する30件のデータを用いて、飛行場から5マイル以内に適用するための落下分布関数(D)を(2)式のように決定した。2.2.飛行場近辺(5マイル以遠) Niyogi等[2]は飛行場に関連する飛行からプラントヘの落下確率を(3)式で評価している。この式は飛行場から5マイル以遠に適用され、飛行形態が飛行場に関して軸対称であるとの仮定に基づいている。2.3.直線航空路 Kenneth A.Solomon[3]は直線航空路からプラントヘの落下確率を(4)式で評価している。そこに含まれる落下分布関数としては(5)式を推奨している。距離減衰係数(g)として、(6)式のように航空機種毎に別の値を提案している。2.4.レーストラックパターン飛行 K.Hornyik等[4]は戦闘機のレーストラックパターン飛行からプラントヘの落下確率を(7)式で評価している。このとき落下分布関数としては単純な近似式として(8)式を用いている。これは事故発生地点を原点とする極座標表示で、半径方向、円周方向共に直線的に低減する形をしている。事故発生時の飛行高さの影響を(9)式のように最大滑空率と最大旋回率で考慮している。Hornyikは文献[5]において、落下分布関数がDとΓで規定される範囲外で0となるのは現実的ではないこと、航空機事故がプラントの極く近く(極めて遠く)で発生したときには過大評価(過小評価)にななることを指摘している。そしてさらに、より現実的な落下分布関数として、半径方向にはガンマ関数を、円周方向にはガウス関数を利用することを示唆している。1985年8月12日に日本で発生した日航ジャンボ機墜落事故はこの提案の妥当性を示している。その事故では飛行機はその方向操縦機能は喪失したが、エンジンは推力を保持し続けた。このような場合には最大滑空率で与えられる範囲を越えた遠方まで到達する可能性がある。本論ではHornyikの示唆に従い、(10)式およびFig.6で与えられる落下分布関数も考慮し、計算例において(8)式による結果と比較した。計算例 Fig.7に示されるレーストラックから評価対象線上にあるプラントヘの落下確率を求めた。Hornyik型のパラメータのうち、最大滑空率(C_d)については10と20の2ケースを考慮した。一方、最大旋回率(C_θ)については0.1度/mで一定とした。ガンマ-ガウス型のパラメー夕(υ,σ_θ)については、(11)式で与えられる2次積率がHornyik型と同じになるよう設定した。(7)式の時間に関する積分は、飛行速度が一定と仮定して線積分に変換し、レーストラックを微少有限線分要素に分割して各要素の和として求めた。計算結果をFig.8に示す。これによると、標的側(右側)は飛行高度が低く最大滑空率で与えられるDが小さいので、Hornyik型の結果は距離の増大と共に急激に値が低下するのに反し、ガンマ-ガウス型の結果は低下の度合いが比較的小さい。距離が5km付近のレーストラックの近傍ではHornyik型の結果はガンマ-ガウス型の結果より大きい。これらの傾向は前述のようにHornyik[5]が指摘した通りである。反標的側(左側)は飛行高度が高いので両関数の結果は5〜25km(C_D=20)あるいは5〜12km (C_D=10)の範囲までほぼ同等の結果となっている。それより遠方ではHornyik型の結果は最大滑空率で与えられるDの制限によりガンマ-ガウス型の結果に較べて急激に低下している。2.5.フリー飛行 ある種の飛行空域では飛行形態に関する情報が入手できないこともある。本論ではこのような空域の飛行をフリー飛行と呼ぶ。著者によりフリー飛行区域近傍に位置するプラントヘの落下確率評価法が提案された。フリー飛行区域内の飛行密度および飛行方向が均一であるとの仮定を用い、フリー飛行に対する落下分布関数として、レーストラックに対する落下分布関数を軸対称に修正して次のように設定した。Hornyik型(パラメータ : C_d)、(12)式およびFig.9 : ガンマ型(parameter : κ)、(13)式およびFig.10 : ガウス型(パラメータ : η)、(14)式およびFig.11 : これらの落下分布関数を用い、(15)式の積分をフリー飛行区域全域にわたって行うことによりプラントヘの落下確率が得られる。計算例 Fig.12に示されるフリー飛行区域からプラントヘの落下確率を求めた。 Hornyik型のパラメータのうち、最大滑空率(C_d)については変数として扱った。ガンマ型とガウス型のパラメータ(κおよびη)については、(16)式で与えられる2次積率がHornyik型と同じになるよう設定した。(15)式の体積積分はフリー飛行区域全体を微少有限要素に分割して各要素の和として求めた。計算結果をFig.13に示す。これによるとHornyik型とガウス型の結果はほぼ同一となっていて、その最大値はC_Dが3近傍で生じている。一方、ガンマ型の結果はC_Dが5近傍で最大値が生じている。この違いの原因としては、Hornyik型の落下分布関数は半径がDより外では0であり、またガウス型のものはexp(-r^2)の形で距離の増加とともに急速に減少するのに対し、ガンマ型はexp(-r)の形で比較的ゆっくり減少するためと思われる。これらの分布関数の差がHornyik型/ガウス型とガンマ型の結果に僅かの差を生じている。しかし年間落下確率という工学的な意味においてはFig.12に示される配置に関しては3種類の分布関数はほぼ同等の結果を与えている。Lothar Sutterlin[6]は評価区域内均一飛行の場合の落下確率評価例を示している。そこでは旧西ドイツ全体に対し飛行密度と事故発生確率を均等と仮定している。文献[6]によれば旧西ドイツ全体(2.5×10^<11>m^2)における戦闘機の年間平均落下数は25機なので、有効面積100m×100mのプラントヘの年間落下確率を(17)式で与えている。3.結論 各飛行形態毎にプラントヘの落下確率評価式を計算例とともにレビューした。レーストラックパターンに対する落下分布関数としてガンマ-ガウス型分布が提案され、Hornyik型による結果と計算例において比較された。フリー飛行区域からの落下確率評価法が新たに提案され計算例が検討された。もし一つのプラントに対し、独立した異なる飛行形態からの落下の可能性がある時は、各飛行形態から得られる落下確率の総和としてプラントの年間落下確率を評価しなければならない。航空機落下の事故原因は、次の三者に大別される。a)機体に原因するものb)制御系に原因するものc)パイロットに原因するもの各事故原因に対して、落下分布関数は異なる形状となるであろうが、本論では事故データの資料不足のためこれらの差異を考慮しなかった。落下確率評価結果の精度を向上させるためには、対象プラントに影響するような航空機事故に対する、より精密な統計量の把握と事故発生機構の調査が重要である。

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In the previous paper it was verified that the distance variable along the stream path was useful to describe the pressure field on the surface of a model in a natural wind. This paper indicates that the more precise analysis is possible by replacing the previous concept of the stream path variation with the curvature of stream path. The discover of the obstruction component in the variation of the curvature against the flow pattern completion clarifies the difference between a flow field in a natural wind and that in a boundary layer wind tunnel in lower Reynolds number condition.

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In this paper, we investigate vertical mechanical characteristics of Base-isolated Rubber Bearings from tensile to high-compressed stress condition (-20〜300kg/cm^2), approaching theoretical and experimental studies. Then we propose the theoretical expression of the vertical stiffness covering both tensile and compressed condition with adopting a concept of equivalent Poason's ratio (υe ). And we carried out experiments using reduced and actual Rubber Bearings those diameters were 7, 16, 25, 50 and 80 cm respectively. Experimental results show that we can express the vertical stiffness by the proposing expression, adopting (for example)υe = 0.25 under compressed condition or υe = 0.02 under tensile condition as concerning actual Rubber Bearing, which first shape factor (S1) is about 32. And further, we get the result that the Bearing's compressed buckling stress is dependent upon the size of S1, and the Bearing's buckling stress can reach 600kg/cm^2 when that is about 32.

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The energy absorption characteristics of mass damper systems in time domain were studied in this paper. The control performance of the semi-active mass damper (SAMD) system was mainly discussed, analyzing two-degree-of-freedom models. Through the results of response analyses under harmonic or random excitations, the efficiency of the semi-active mass damper system was proved. The analyses also proved that the SAMD system has an optimum control gain magnitude which maximizes the vibration control efficiency. It was demonstrated that a couple of SAMDs were effective for reducing the transverse-torsional vibration response of a building against wind excitations.

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A new algorithm is presented for design sensitivity analysis of elasto-plastic response of trusses. The algorithm is based on the incremental perturbation method which utilizes the higher order differential coefficients of response with respect to a loading or path parameter. All the governing equations are differentiated with respect to the design variable to find the sensitivity coefficients of the response variables such as displacements and stresses as well as the values of the path parameter at which yielding or unloading occurs in a member. Since the proposed algorithm incorporates the formulation of the incremental perturbation method for response analysis, and since no iterative process is needed, the design sensitivity coefficients of good accuracy can be easily calculated. Efficiency of the proposed algorithm is demonstrated in the examples of plane trusses and the results are compared with those by the Newton-Raphson type iterative algorithm.

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In this paper, we present a generalized formulation of thin-walled beam theory considering the effect of out-plane distortion due to shear in flexural-torsional problems. By using the finite element method based on this theory, the shear-lag effect of the beams with general shaped cross section can be analysed accurately. By the application to the structural optimization analysis of highrise building, the accuracy and efficiency of this method is verified.

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Recently, in order to conquer the various troubles of the structures with a point bearing pile in a zone of ground subsidence, and for rationalization of a method of foundation construction, the examples of the structures which use a friction pile or a imperfection point bearing pile are on the increase. However. it is conceivable that the differential settlement of these foundations cannot be disregarded. Accordingly, in case of useing such a foundation, it is necessary to consider how to cope with the differential settlement of structures by the exact inference of the differential settlement. I n this paper, we propose the practical analysis method for the differential settlement of the structures with a pile or a piled-raft foundation. And by the numerical example that use this present method, we investigate the behavior of the structures in case that the differential settlements of a pile or a piled-raft foundation arise.

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A critical behavior of timber single-layer lattice dome is simulated by the beam-column finite element method for large deflection analysis of space frames. The beam-column FEM modeling of the steel joint-members of lattice dome enables to predict accurately the equilibrium path with critical behaviors. Governing equations in the numerical method used here are formulated with the incremental perturbation method. Therefore, a proper step length at every incremental step is automatically provided even in the vicinity of critical points on equilibrium path. This paper shows that the numerical method adopted here can sufficiently predict the rotational buckling of joints observed in the full scale experiment. This numerical method is demonstrated to be very effective for simulation of critical behavior of timber lattice domes with gusset plate type joints.

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The present paper investigates the dynamic response of single layered reticular domes simultaneously subjected to horizontal and vertical earthquake motions. A dome which is assigned a safety factor ranging from two to four against the limit state for dead load is analyzed dynamically to the earthquake motions of Taft, El-centro and Miyagi-oki earthquakes. The collapse acceleration that is defined as the minimum acceleration enough to cause the dome to collapse is evaluated. For the dome with a safety factor of two, three and four, the collapse accelerations are found, respectively, 167, 473 and 778 gals. Based on the results, an formula to estimate the collapse acceleration is given by using the relative displacement response spectra for earthquake motions.

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The deflection behavior of rigidly jointed single-layer latticed domes with several triangular networks subjected to a vertical concentrated load and/or uniform pressure have been studied experimentally. On comparing of the experimental results with calculated ones of finite element method, close agreements between them were obtained. The results indicate that the dome tends to buckle more easily as the distributed load increases and that the buckling characteristics depend on the Shell-likeness Factor S. In applying a concentrated load to the apex of the dome, the deflection characteristics standardize those for the other junctions.

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In recent years, extensive analytical and experimental studies have been carried out to establish a rational structural design method for reinforced concrete structures against local damage caused by the impact of various external projectiles. Through these studies, several techniques for improving the impact resistance of reinforced concrete plates have been proposed. Of these techniques, attaching a steel liner on the rear face of the plates is considered to be one of the most effective methods. The object of this study is to evaluate quantitatively the effect of a steel liner attached to a reinforced concrete plate in preventing local damage caused by the impact of rigid projectiles. To achieve the object, extensive impact tests were carried out with a total of fifty reinforced concrete panels of 60cm-square. Based on test results, the effect of a steel liner on both scabbing and perforation was evaluated quantitatively by converting steel liner with a certain thickness into the equivalent concrete thickness. And evaluation of the liner effect was attempted analytically using the Discrete Element Method and the fracture process of various damage modes with and without the steel liner could be well simulated.

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The plastic deformation capacity of H-shaped steel beams is reduced with web openings as well as yield strength of ones. The final configuration of such beams is specialized with the collapse mechanism near holes. This deformation pattern causes the less of strength of beams. Then we suggest the new recovery method of plastic deformation capacity at the standing point of the constraint of the above local deformation pattern near holes. Here, we discuss the effect of such constraints numerically and experimentally.

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This is a report of experimental investigations of shear rigidities of thin steel plates and films with openings or inner slits. The rigidities of above members which are surrounded by the pantograph frame are obtained from "opening ratio" and "slit ratio", the former is well-known at the reinforced concrete wall is applicable. The boundary between openings and slits are verified. In case of the ratio of the width of a slit to the length of a side of above members is more than 3 to 5 percents, it should be treated as an opening. Each effects of openings and inner slits to the rigidities are estimated from "resisting area ratio" by thin films.

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Brittle fracture of structural steel for building use, in general, is triggered by a ductile crack initiated at notched surface after undergoing a noticeable amount of plastic strain. This study showed the conditions governing the initiation of such a ductile crack in conjunction with the notch sharpness, material properties, and specimen size. Monotonic tensile test of round bar specimens having a circumferential notch at the center was performed to observe the behavior of crack initiation, and then finite element analysis was done to investigate the triaxial states of stress and strain in the notched section. Major findings are as follows : The crack initiation strain tends to increase with the reduction in stress triaxiality underneath the notched surface and with the increase in uniform elongation capacity pertinent to the material, and their mathematical relation is proposed in an experimental formula. Furthermore, it is clarified that size effect is not involved in the crack initiation.

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This paper proposes a technique to reduce the weight of tubular structures by reducing the size of the gusset plate in the tube to gusset plate K-joints. The eccentric joint where the intersection of the gravity axes of branch pipes are shifted to the gusset plate side can reduce the gusset plate length. Therefore, we deduce the strength equation applicable to the ultimate strength of the main tube on the eccentric joint. The strength equations agree approximately with experimental values. Especially, in case of the slenderness ratio is 40 or less, the inner eccentric joint proves to be an effective measure.

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A study is made on theoretical clarity as well as practical applicability of the simple plastic theory for the prediction of the ultimate states of steel frames subject to fire. Ultimate temperatures of simple steel frames were estimated by two different means ; i.e., by a refined finite element analysis which takes material and geometrical nonlinearities as well as thermal expansion into account and on the basis of the simple plastic theory which considers solely reduction in material yield strength according to temperature increase. The latter solution is called herein a primary ultimate temperature which is a simple structural characteristic quantity independent of thermal stresses. Comparison of both solutions leads to the results that the primary ultimate temperature is not only a first order ultimate temperature approximation but it also plays the part of reference quantity for the evaluation of stability or other second order effects on the ultimate temperatures of steel frames.

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Strengths and rotation capacities of concrete-filled steel circular and square section columns subjected to repeated and reversed bending under constant axial thrust are estimated using the effective steel and concrete strengths which were derived from the stub-column test results. These theoretical predictions are compared with experimental results hitherto reported to demonstrate the validity of the predictions. The rotation capacities of the columns obtained by tests are analysed, and a related width-to-thickness ratio limitation of the columns is suggested.

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When steel and concrete composite structures are designed by using the limit state design method based on the reliability analysis, it is required to obtain appropriate resistance factors for members in the structures. The purpose of this paper is to obtain resistance factors for two types of composite columns on the ultimate state. One of the types is steel reinforced concrete columns and the other concrete-filled tubular columns. The resistance factors are determined by considering probabilistic properties for both member strengths and applied loads including seismic forces. Therefore, the load factors for the composite columns are also discussed in the paper.

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As concerns a mathematical model for the prediction of velocity of the smoke front which was presented in part 1, new method for taking account of the effect of the inertia is formulated. The effects of heat loss from smoke layer to the surroundings are also considered by the theoretical model being able to consider temperature dependence of total heat transfer coefficient. The prediction of these models is compared with the field experiment and with the model experiment using high temperature smoke.As a result of these improvements, the errors caused by the effect of the inertia are decreased, and, in case of prediction of high temperature smoke in a long corridor, the new model gives more accurate results than the previous.

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A model of heat and mass transfer in concrete during fire was presented. The model takes into account the 1) conduction of heat, 2) filtration of gas in the pore, 3) diffusion of water vapor and adsorbed (liquid) water through the pore, 4) desorption of adsorbed water and 5) decomposition of water of crystallization. The rates of desorption of physically adsorbed water and of decomposition of water of crystallization were explicitly expressed. The calculated results of temperature, pore pressure and water contents were compared with experiments on cement mortar walls. As to the temperature, the agreement was very good, including the phenomenon of creeping of temperature. As to the water content and pore pressure, the agreement was not perfect quantitatively but good qualitatively. Therefore it can be said that the model is valid to predict the temperature changes of concrete members during fire.

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