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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Formulae for estimating the probability of an aircraft crash into an important facility are discussed. Four formulae introduced in the references are reviewed and are used to estimate the probability of an aircraft crash based on four flying patterns, namely, "Landing on and/or taking off from an airport", "Near airport", "Straight flight path" and "Racetrack pattern flight". For "Racetrack pattern flight", a new crash site distribution function is introduced and sensitivity analysis of crash site distribution functions is conducted. Finally, a formula for estimating the crash probability for a "Free flight zone" is newly proposed and a sensitivity analysis is also conducted. All formulae are accompanied by numerical examples idealized to flying conditions.

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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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