Wind force of photovoltaic arrays are usually designed based on JISC8944:2004. The wind force coefficients described in JIS are determined by wind tunnel test conducted in NEDO. Wind forces are likely to be over-or under-estimated depending on the size of arrays, because the wind force coefficients are calculated as mean values of the array. In this study, wind pressure distribution on photovoltaic arrays with module angle 10 degree are precisely investigated by wind tunnel tests. Furthermore, LES analyses are conducted to clarify the aerodynamic characteristics of the arrays. Due to the experiments and LES analyses, it was found that conical vortexes are generated from edge of the northernmost array, and significant negative pressure are developed around the edge.

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To investigate the galloping phenomena of overhead transmission lines under ice accretion, field observations of four-bundled conductors were carried out at the Tsuruga test lines. On December 21, 2009, the galloping of overhead transmission lines with ice accretion was observed at this site. The conductors mainly vibrated in the vertical two-loops/span mode coupled with the horizontal and torsional modes. Statistically, th e range of wind speed where galloping occurred was limited for some region. The following discussion is derived as the factor. The static angle of attack increases with the wind speed. When the angle of attack increases to values that meet the Den Hartog criterion, galloping occurs. When the wind speed increases further, the angle of attack exceeds the range of values meeting the Den Hartog criterion and the oscillation amplitude decreases.

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In this study, the aerodynamic coefficients of four-bundled conductor models, where pennant shape of ice and snow accretion was simulated, were obtained by wind tunnel tests in order to investigate the effects of initial angle of ice and snow accretion growth on the aerodynamic force. Surface pressure on conductor models was also measured to obtain the individual aerodynamic coefficients of each subconductor. The measurement results show that the aerodynamic coefficients vary depending on the initial angle of ice and snow accretion. The effects of the initial angle of ice and snow accretion on conductor galloping were quantitatively evaluated based on Den Hartog criteria. The result shows that the effects should be considered when evaluating galloping response of four-bundled conductor.

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Kanmon PC slabs, which have been used over 53 years, were estimated for the effective prestress based on the Stress-releasing Method. By contrasting three sets of cases, smaller core size and drilling from the greater strain surface, are concluded to make the method more reliable. To examine the method and check inner stress and strain change of the drilled core, a FEM analysis is conducted. Then through the comparison of results with experiment, they can almost coincide, which verifies the reliability of the method. Obtained from both experiment and analysis, strains will be almost released in depth as about 0.3 times of the core's diameter.

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Fatigue cracks have occurred around welded joints of sole plate in composite girder of Sanyo-Shinkansen. Generally, main factor of these cracks is deterioration of movability of bearing. And replacement of sole plate and bearing is effective for reducing this fatigue damage. However, the cost of this construction is high, so development of alternative method is imperative necessity. In this study, we developed easy and low-cost reinforcement method by FEM analysis and test construction. As a result, it was found that installation of angle steel with vertical rib to the upper side of lower flange was effective as reinforcement for fatigue damage of welded joints of sole plate.

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Much fatigue damage has been observed in connections between stringers and floorbeams in initially-welded steel railway trough girders. This paper addressed the retrofit work for the fatigue cracks. Stress measurement on the existing bridge and Fine meshed FEM analysis were conducted to clarify the cause of fatigue cracks. Based on the parameter studies on FEM, we proposed the retrofitting method called “Ship Shaped Reinforcement”. Stress measurements were also carried out after applying the reinforcement to confirm the efficiency. As a result, we found the sufficient reduction of stresses around the fatigue damaged areas.

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In the CFRP repair of steel bridges in service condition, not only steel members, but also the CFRP strips and epoxy resin adhesives in situ are subjected to cyclic stress and vibration generated due to traffic load. The aim of this study is to investigate for the effects of the fatigue crack repair using CFRP strips and epoxy resin adhesives under dynamic load during curing. First, experiments have been carried out using coupon specimens of steel plates with through center crack. Second, FEM analysis hase been carried out to predicate the fatigue crack propagation, and compared it with the experiment results. As a result, it can be considered that bonding repair in service conditions will not affect to the fatigue life, and it was confirmed feasible for practical use.

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This study proposed a simple method for estimating local stresses in as-welded joints and established a fatigue assessment method by using the estimated local stress. In this method, the local stress at the as-welded toe is estimated from the stress at the weld toe finished by grinding, where the stress can be measured by strain gauges. Fatigue tests and finite element analyses were conducted with out-of-plane gusset welded joints in as-welded and finished conditions. Based on the results, the local stress at the as-welded toe was correlated with the stress at the finished groove. It was concluded that the fatigue strength of the as-welded joints can be evaluated by using the local stress estimated by the proposed method.

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The deicing salt spreads larger amount and more frequent after the moratorium on the use of spiked tire. There are many damage in steel bridges by spreading decing salt. The cases of the deicing salt adhesion to girder are water leak which include deicing salt, and scattering of deicing salt by wind and traffic passage. However, it isn't evident that the effect of scattered deicing salt for steel bridges. In this paper, relation between amount of spreading deicing salt and airborne salt, adhering salt to girder, corrsion of test piece using weathering steel are observed.

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It is important to estimate corrosion environment of steel bridges for a proper corrosion prevention and maintenance program. Adhered sea-salt particulate matter (SSPM) is an influential factor especially in coastal areas. To this end, it is better to know the adhesion behavior of SSPM to bridge girders. The objective of this manuscript is to pursue numerical method to simulate the adhesion behavior of salt particles oriented from sea surface. Specifically, two scale approach is proposed. Mesoscale Meteorological Analysis and Lagrangian type two phase flow analysis are used in global and local analyses respectively. The comparisons between the numerical and observed results showed that the numerical analysis can reproduce essential behaviors of airborne SSPM.

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The important accidents that the diagonal members of the steel truss bridge have broken due to severe corrosion damages occurred recently. Therefore it is expected to establish the rational and efficient maintenance management technique depending on the bridge type and structure characteristic. Especially, the corrosion damages of the main members may have a serious influence on the safety of the bridge system, and the technique for the investigation and checking is appropriately demanded. In this study, for the corroded gusset plate connection which was cut out from the steel truss bridge, we measured the corrosion shape in detail using the surface roughness measurement equipment, and evaluated the actual state by the surface corrosion of the outside and the narrow inside of the gusset plate connection.

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Reliability of cross-sectional average thickness, which is obtained from thicknesses measured by ultrasonic measurement in site, is investigated for a steel tubular pile corroded under marine environment, and the thickness to evaluate the remaining strength is proposed based on the measured thicknesses. Using three types of corrosion, splash zone, tidal zone and seawater zone, of steel tubes exposed in marine environment for 19 years, it is confirmed that the thickness can be given by the average thickness and standard deviation calculated from measured thicknesses. From the results, it is concluded that the remaining strength can be evaluated safely by the thickness given by subtracting the standard deviation from the average thickness.

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In this paper, in order to study on bending behaviors of a riveted steel girder with corrosion damage at heads of some rivets, bending loading tests are carried out. The steel girders used as specimens were cut out from the bridge that had been used for 55 years. Considering the results of the bending experiment, it is found that the initial rigidity of the specimen with the rivet heads corroded is decreased a little. But the effect of corrosion damage at rivet heads of riveted steel I shaped girder for ultimate load is nothing.

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The objective of this study is to investigate experimentlly the effect of repair method using carbon fiber sheet (CF sheet) for corroded web located at the ends of steel girder bridges. Shear buckling tests were carried out using steel girders with the reduced thickness at the bottom of the web. CF sheets were bonded partially or wholly on the web through polyurea putty. It was confirmed from experiment that when the thickness of the web reduces 50% and 100%, shear load-carrying capacity reduces 10.4% and 21.0% respectively compared to intact case. When CF sheets were partially bonded on the web with the fixation on lower flanges, shear load-carrying capacity was restored. Futhermore, when CF sheets were bonded on the whole surface of the web, shear load-carrying capacity was also almost recovered even though CF sheets were not fixed to the lower flanges.

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We have developed the integrated structure of existing railway steel girder, abutment and earthfill, which can improve aseismic capacity of structure and load carrying capacity of steel girder, and reduce the maintenance costs for girder supports. On the other hand, thermal deformation and stress are increased by connecting rigidly girder to abutment, and this thermal impact can be one of the dominant factors to design the integrated structure. In this study, the thermal responces were grasped by monitoring the full-scale integrated structure which was constructed in our institute, and attemped to verify the design method.

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At present, the performance for fire resistance of the bridge is not generally required in its design. However, many examples damaged by a fire due to traffic accident under the bridge, doubt fire, incendiary fire and so on, have been reported. Therefore, the authors are developing the fire protection panel which is composed of the Autoclaved Lightweight aerated Concrete (ALC) and Ceramic Fiber Blanket (CFB). In order to confirm the performance of the fire protection panel, the authors carried out the fire test by applying Hydrocarbon curve given by Eurocode. In this test, the thicknesses of the ALC and CFB are changed. This paper deals with the test results of the temperature and deflection distributions of the fire protection panel.

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Load bearing deterioration of existing transmission towers due to unequal base displacement is estimated by numerical analyses and measurements. However, the accuracy and efficiency improvement of the practical analysis technique is inevitably requested, because of a lot of anxiety towers that should be diagnosed. The purpose of this paper is to confirm the proposed analysis method paying attention to nonlinear behaviors practically, such as ratio of construction error to total base displacement and bolt slipping stress. It was clarified that the present method is remarkably improved from the viewpoint of accuracy and efficiency improvement compared with the current method.

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Recently, it has become more and more important to establish a rational maintenance program for infrastructures. In bridge structures, concrete slabs are suffering from damage, because they directly resist applied loads. In this study, an attempt is made to develop a new damage detection method for concrete slabs with cracks, by using pattern recognition techniques. In the pattern recognition, the feature extraction is a quite important process, because the recognition rate depends on the characteristic of the recognition object. The previous research proposed the method which can select efficient features among various features. However, the method can't apply the problems with many input values. The proposed method can deal in those problems by introducing ID3 with classifiers consisting of many feature vectors. Numerical examples are presented to demonstrate the efficiency and applicability of the proposed method.

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In order to examine or repair fatigue damaged steel bridges, it is necessary to obtain information of mechanical and chemical properties of steel of damaged members or joints. However, for the aging bridges, it is sometimes difficult to obtain such kinds of information from design articles. For such case, a sample material might be taken from the structures, but the sample should be as small as possible. This study examines the use of small steel pieces regarded as cores, which are taken from stop-holes or bolt-holes. Test specimens for Charpy impact test are made with small steel pieces by Electron Beam Weld (EBW) and the effect of the steel piece size and the other parameters on Charpy absorbed energy are examined.

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China timber arch bridge is a special bridge type, in which the arch ring is woven from two polygonal arch systems. There are more than 100 such bridges survived in Fujian and Zhejiang Provinces. Its traditional construction technology handed down from ancient to today generation by generation through oral teaching has been listed in the Urgent Safeguarding List of Intangible Cultural Heritage by UNESCO in 2009 because it is now at a risk of disappearing. To record down the technique is one of the key issues to preserve the intangible cultural heritage. This paper gives the general description of China timber arch bridges and discusses their traditional construction technology.

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In all-wood-type wooden check dam in Akita Prefecture, lag screws and deformed steel bar are utilized as the connectors. From many failure tests of wooden check dams, it was confirmed that the structures with these connectors have very high strength for pull -out and shear behavior. Recently, general purpose utilization of lag screw and deformed steel bar to other wooden civil engineering structures is considered. However there are few examples reviewed pull-out strength of lag screws and deformed steel bar. Therefore, in this study, we conducted many pull-out test of lag screw and deformed steel bar with different pre-drilled hole diameter, and we tried formulization of each pull-out strength.

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The timber members were fastened to a bolted steel connection in timber bridges. The bolt holes in the timber were often made to be larger than bolt diameter to avoid the splitting of bolt holes and breakage of the bolt screws in setting up bolts into the holes. Therefore, a resin was filled into the clearance between the bolt and the bolt hole to prevent a backlash by the clearance. It has been predicted that the filled up resin contribute to the improvement of the performance of the bolted connection. And, the effect of the resin on the connection behavior has not been sufficiently clarified. The static tensile tests changed the parameter such as the resin thickness or the bolt diameter were carried out to clarify the effects of the resin to the pull-out properties which were the loading capacity, pulling-out behavior of timber from steel connection and strain distribution of timber near bolt.

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On the site of the maintenance and strengthening work for steel bridges, the high strength bolted friction type joints are often applied. But, the surface preparation of the existing steel m ember may not be able to be processed adrasive blast-cleaning depending on site conditions. Therefore, the slip tests were carried out using splice plates processed the inorganic zinc rich paint on surfaces and connected plates varied surface preparation and the kind of painting specification on surfaces. As a result of the slip test, it was found that the slip coefficient of 0.4 or more can be ensured by the surface preparation with the power tool.

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In this study, we investigated the fatigue strength of butt weld joints with 10% or more misalignment of the plate thickness, through fatigue tests of 3 girder specimens that have aligned butt weld joint, 18% and 36% misaligned butt weld joints against the 11mm-thick plate in the bottom flange. And we also verified the effect of the taper grinding and toe grinding against the misaligned butt weld joints. As a result, it was confirmed the fatigue strength of 18% or less misaligned butt joints was satisfied JRA Class D and that of 36% misaligned butt joint may not be satisfied JRA Class D. By taper grinding and toe grinding, the fatigue strength of 36% misaligned butt weld joint was improved about 1 rank.

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A simulation analysis of fatigue crack propagation path of out-of-plane gusset joints under out-of-plane bending by XFEM was conducted. Fatigue crack propagation path was obtained from bending fatigue tests. Some modeling techniques, such as mesh size and an initial crack, were investigated through comparing previous research. By comparing fatigue test results with the XFEM analysis results, it can be said that the XFEM analysis can reproduce fatigue crack propagation path of out-of-plane gusset joints in the thickness direction. However, it is necessary to investigate futher fatigue crack propagation path of the width direction by changing weld modeling. Moreover, influences of plate thickness on fatigue crack shape could be confirmed in XFEM analysis.

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Loading experiments using specimens of reinforced concrete beams were carried out. The specimens had been received chloride induced damage by being exposed to dry and wet environment. Based on the results of the experiments, the relationship between cross-sectional loss of the reinforcements in concrete, corrosion crack width on the concrete surface and load-bearing capacity of the reinforced concrete member was researched.

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Analytical model developed by the authors, using three-dimensional Rigid-Body-Spring-Method (RBSM) combined with a three-phase material corrosion-expansion model, was verified against experiments in the case of multi-rebar corrosion. The experiments of beams having multi-rebars were carried out by the other researchers using electric corrosion tests. The applicability of the analytical model was confirmed in terms of crack patterns, surface crack width and internal crack propagation due to multi-rebar corrosion. Moreover, a mechanism of crack propagation in concrete due to multi-rebar corrosion was investigated and compared with the case of single-rebar corrosion analytically. As a result, it was found that rebar spacing strongly affects crack patterns and crack propagation mechanism of concrete. Internal cracks are dominant rather than surface cracks and the propagation of internal cracks combined with surface cracks may cause de-lamination of the concrete cover.

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By using specimens due to ASR which were simulated according to actual structures, authors carried out a long-term measurement of the external cracks in the specimens at outdoor environment. Moreover, the internal cracks, the compressive strength in core and cracks of reinforcing bars, have been justified at the low, middle and the high reactivity during the deterioration in ASR. It was confirmed that compared with the internal cracks, the apparent cracks were relatively wider and longer. The comparison of strengths between health core and ASR core was conducted as well. With the difference of diameters between 30mm and 190mm, it was confirmed that the compressive strength reduced about 30%.

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A criterion in non-destructive test method for fracture of reinforcing steel bars by measuring magnetic flux density was established. The steel bar is ferromagnetic. With being magnetized with a magnet from on the surface of concrete cover, disorder of magnetic flux appears near the fractured part. The diagnosis could be done at the bent part of the reinforcing steel bar clearly using proposed criterion with taking degree of the disorder into account in model cage assemblies of steel bars. The criterion was also applicable for existing reinforced concrete beam members in road bridge substructures.

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In order to investigate improvement in ductility of Reinforced Concrete (RC) piers due to mixing Poly-Vinyl Alcohol (PVA) short-fiber, lateral cyclic loading tests of RC piers were conducted taking with/without stirrup and fiber mixing volume ratio V_f as variables. In this study, normal concrete and PVA short-fiber mixed concrete with V_f= 1, 2, and 3 % were used. From this study, following results were obtained: 1) ductility of RC piers can be improved due to mixing PVA short-fiber in spite of with/without using stirrups; 2) stirrup and PVA short-fiber can be independently affected to improve in ductility of RC piers; and 3) the ductility of the RC piers may closely relate to a shear-bending capacity ratio at the basement of the pier mixed PVA short-fiber.

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In this paper, generation and development of the interface corrosion between steel and concrete are investigated using the element test specimen which simulates the actual interface condition of the hybrid structures. The two types of element exposure tests are conducted, that is, the test focusing on the effect of the different environment of corrosion condition, and the test focusing on the effect of the bond between steel and concrete. Moreover, the effect of humidity on the interface neutralization and corrosion is investigated. As a result, the mechanism of generation and development of the interface corrosion between steel and concrete is predicted based on the experimental data.

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The hybrid rigid frame bridges have been widely applied in road bridges. However, this type of structure has rarely been applied for railway bridges. To encourage its application to railway bridges, it is necessary to extend its applicable range to longer span around 100 m. In this study, cyclic loading tests of the girder-to-column connection that has steel box girder and box-shaped anchor beam were carried out in order to clarify the structural performance of the connection with the anchor beam, such as load-carrying capacity and ductility. As a result of the tests, applicability of this structure to large span and validity of the design method were confirmed. In addition, structural details of the girder-to-column connection, such as appropriate length of anchor beam, were determined using the test results.

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Robinson type composite deck in which concrete and base steel plate are connected by headed studs is typical and major among composite decks in Japan. As the fatigue durability of the composite deck mainly depends on the fatigue strength of studs, the authors have developed an improved welding ferrule for the stud. The ferrule has upper grooves to spout out shield gas at welding and has a closed skirt to store melted metal and to make the welded bead shape of the stud smooth. In this paper, shear-tensile fatigue tests and rotating shear force fatigue tests were carried out to certify the effect of improvement. Consequently, the authors have confirmed its superior durability over the conventional studs.

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The efficient maintenance of the steel bridges is considered to be important. The hybrid structures in this study, the steel bridges are composed with concrete members. As a result, it prevents corrosion. In addition, the stiffness increases from the bridges of only steel members. The bridges will be able to last for a long time by these effects. However, it tends to crack by its thermal stress when concrete hardened. If a concrete thermal gradient is reduced, the crack is suppressed.

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Maintenance of existing steel structures has been a hot issue in recent years. A hybrid bridge was created from an original steel structure by integrating with the concrete members. The purpose of the present study is to investigate the mechanical behavior of the renovated girder. Based on the experimental observations, a three-dimensional FE model capable of analyzing these kinds of composite structures was built. Strength and deformation response, sectional strain distribution and movement of composite neutral axis before and after concrete cracking were observed in the test and compared with the numerical results, and the results predicted by this modelling method are in good agreement with those obtained from the tests. Results indicate that the renovated structure can greatly enhance the stiffness and reduce the stress levels, resulting in the extension service life of the structure.

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In this study, to investigate frictional behavior and maximum strength of GFRP members connected by high strength bolts and splice plates made of stainless or GFRP plates, slip test and bolt relaxation test are carried out. And FE analysis is executed to study on mechanism of stress concentration. From the slip test, slip coefficient of the specimen with stainless splice plates is lager than 0.4 and it is found that the slip coefficient can calculate by toribology theory. From the FE analysis, the maximum strength of the GFRP firictional bolted joint can estimate based on consideration of stress concentration. Relaxation test for one year provides the amount of decrements of the bolt axial forces of each connection.

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This paper presents an experimental study on the flexural behavior of CFRP box beams with two laminate structures fabricated by VaRTM method. The two laminate structures are a cross-ply (CP) and a quasi-isotropic (QI). Three specimens are prepared for each laminate structure. The specimens are tested under four point bending. The bending tests show that initial stiffness of each specimen corresponds to the one calculated by Timoshenko's beam theory and that the two laminate structures affect longitudinal normal strain and in-plane shear strain. QI exhibits higher flexural strength than CP, and they fail with different failure modes. Moreover, it is shown that the flexural strength calculated based on beam theory and Tsai-Wu criterion agrees relatively with the experimental one.

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The necessity of earthquake-resistant reinforcement for underground structure in large-scale earthquakes is rising. This paper shows a model test of the reinforcement method using the ground solidification body and its FEM analyses that were conducted to examine deformation characteristics of the reinforced underground structure and the effect of the reinforcement. Target underground structure is RC one-box culvert and the loading tests were performed by using the 1/3 scale RC model. The reinforcement body made with cement and clay was situated on both sides of the structure. The effect of the reinforcement was confirmed by comparing the results of the experiments with the earthquake-resistant reinforcement and without it. And elasto-plastic FEM analyses could reproduce the behaviors of the underground structure in the loading test.

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Structural behavior and residual structural capacity of 2-way reinforce concrete (RC) slabs against punching shear failure were investigated through static loading tests after falling-weight impact loading tests. It was found that punching shear capacity of RC slabs damaged by repeated impact loads slightly decreases compared with non-damaged slabs just before the occurrence of punching shear crack. It was also found that punching shear capacity rapidly declines after formation of cracks due to punching shear at the bottom surface of the slabs. Based on the test results, the method to evaluate punching shear resistance of RC slabs subjected to repeated impact loads was proposed. Furthermore, the applicability of the proposed method to 1-way slab was examined.

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The aim of this study was to investigate the dynamic shear failure behavior of reinforced concrete (RC) beams under rapid loading through an experimental study Thus, rapid loading test for 48 RC beams was performed, in which shear span ratio, shear reinforcement ratio and loading rate were variable. The RC beams exhibited diagonal tension failure, shear compression failure and flexural failure depending mainly on the shear span-to-depth ratio and shear reinforcement ratio. The maximum resistance of the RC beams was also significantly dependent on the loading rate, shear span-to-depth ratio and shear reinforcement ratio. Finally, based on the failure modes observed, a strut-tie model with loading rate effects was developed to evaluate the dynamic shear reistance of the RC beams.

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The series of the H-beam experiments under impact load as a rockfall phenomenon was introduced. The experimental results were evaluated focusing on the impact characteristics and behaviours of steel beam as a simple protective structure. Validity and effectiveness of numerical analysis by a finite element method were confirmed by comparing with the experimental results considering rate effect. The simple method to estimate the accurate deflection of the beam by impact was discussed by numerical simulations under some conditions. The equations to estimate the maximum deflection and the residual deflection against impact were proposed using simple parameters, namely the input kinetic energy, the yield bending capacity and the span length of beam. The proposed equations were verified by using the performance indexes comparing with the experimental results, and were used as a performance based design to predict the failure on the structure while resisting impact load.

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In order to establish an impact-resistant design procedure for reinforced concrete slabs, the effects of the supporting conditions and thickness of the slab on impact-resistant behavior of the slabs under the consecutive impact loading were experimentally investigated. The supporting conditions considered here are: line supports on four sides, two line supports on two opposite sides, and one line and two corner-point supports. The results obtained from this study were as follows: (1) Even though development of the flexural cracks were affected by the supporting conditions, finally punching shear cracks were formed irrespective of the supporting conditions and magnitude of the slab thickness; (2) the maximum impact force tends to increase according to an increase of the slab thickness; and (3) the case of the line supports on four sides gives the highest impact-resistant capacity for the slab among three kinds of supporting conditions considered here.

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This study is focused on two types of shock absorber of a bridge restrainer system: one is fiber reinforced rubber-rolled pin and the other is fiber reinforced rubber-rolled pin with steel pipes at the inner and outer edge of the rubber. First, applicable limit of the shock absorber was defined and 3D FE analysis was conducted to determine equivalent imp act condition under using a drop weight impact machine. Second, single and repeated impact tests were performed to compare the mitigating effect and the damage of a pin. As a result, it was confirmed that the elastic limit and mitigating effect were quantitatively evaluated by comparing of two types.

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The huge tsunami caused by the Great Tohoku Earthquake devastated the coastal regions on March 11, 2011. In addition, risk of flood disaster has been increasing because of the global warming, and flood disaster prevention and/or -reduction is one of the important issue. In the design of protective structures against for the water-induced impact force such as seewalls and mud-slide control dam, the accurate estimation method of impact force is strongly desired. The numerical simulation is one of the most promising solutions. In this research, Lagragian 2D, 3D particle methods and Eulerian FEM, FDM methods are adapted to estimate fluid impact force. The accuracy of the estimated fluid impact force has been investigeaged by comparing with an experimental result and the design force in the mud-slide control dam.

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In order to establish performance-based impact resistant design procedures for reinforced concrete rockfall protection galleries, numerical simulation for a half scale rock-shed model was conducted to investigate an impact resistant behavior of the structure. Here, 3D elasto-plastic FE analysis method was employed for this numerical analysis. The results obtained from this study were as follows: (1) varying the location of the loading point under a constant input impact energy, the damages in the cases of surcharging impact force near free edge of the gallery were more severe than those in the case at the center of the gallery block; and (2) the distribution of the maximum weight impact force with input impact energy in case of surcharging the impact load at the mid-span of the free edge was numerically evaluated to be almost similar to that obtained from the experimental results surcharged at the center of the gallery block.

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This paper presents numerical simulation of the failure of reinforced concrete slabs subjected to underground explosion. Firstly, previous engineered soil model is improved so that attenuation with distance is more reproducible. Two dimensional and three dimensional simulations with the proposed model are conducted and validated by comparison with test results. Then failure of reinforced concrete slabs subjected to underground explosion is analyzed by three dimensional analyses with the proposed soil model. The numerical results show good agreement with the test results.

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In order to gain a basic knowledge for formulating material constitutive model of sand cushion, a falling-weight impact test was conducted varying thickness of cushion material, compaction level, and mass of falling weight as variables. The results obtained from this study was as follows: 1) in the relationship between surcharged force and strain of the sand layer, the sand behaves elastically in the beginning of impact, after that the force was gradually increased in the region of moderate strain, and finally that was abruptly increased parabolically; 2) the first peak of the transmitted impact force was larger than the maximum impact force; and 3) the whole of input impact energy due to falling weight impacting may be perfectly absorbed by movement of the sand.

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In order to establish an impact resistant design procedure following performance-based design concept, here, impact response characteristics of a large scale reinforced concrete beam under continuous and distributed falling-weight impact loads were numerically investigated. In this paper, under the condition of the resultant input-impact energy being kept a constant as E_w=196 kJ, falling height of weight, number of weights, and interval time of weights falling were taken as variables using 2,000 kg steel weight. As the results, it is confirmed that (1) maximum, residual, and accumulated residual deflections in the case of the falling weights impacting at the same time are larger than those in the case of the weights impacting continuously; and (2) the lower the falling height of weight and heavier the total weight, the larger the maximum and residual deflections are.

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In this study, in order to establish a numerical analysis method for better evaluating impact response behavior of the large scale reinforced concrete slabs, 3D elasto-plastic FE analysis method was conducted for falling-weight impact test and its applicability was investigated by comparing with the experimental results. The results obtained from this study are as follows: (1) the maximum and residual deflections, and crack patterns were roughly evaluated by using the proposed numerical analysis method; and (2) the most accurate results were obtained taking the mesh size in the plane direction as 16 mm, but the residual deflection was not still accurately evaluated.

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The joints of bridges are likely to be damaged by the traffic and are often deteriorated by the drainage of rain and thawing agents. Hence the non-jointification of the floor slab is preferred. We here proposed a non-jointification of the extended floor slab and examined sizes and shapes of the slab and the support as well as their material parameters. Finite element analyses of an arch bridge subjected to the traffic and thermal loads with the effect of the contact phenomenon between the slab and the support showed the feasibility of such a connection located at one side of the bridge.

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