In this study, the damage detection system based on the structural health monitoring is proposed. The system is built by analyzing a relationship between the prediction error of the car-bridge coupled vibration and the bridge damage level with a neural network. In this paper, the mechanism of detecting the damage level from the prediction error is shown and examined by using the traffic induced vibration obtained by the numerical simulation. Also it is tried that the relationship between the error and the damage level is generalized by considering the sampling frequency and the natural frequency of the bridge.

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About fifty years have passed from the peak of the hydro power plant construction and aged waterway steel structures have increased considerably. In order to regulate the water, sluice valves are generally used, and the valve leaf shall be so structured as to be strong, rigid and safe enough against hydro pressure, because the valves are set up in the body of dam and neither the inspection nor the maintenance are easy. As the anxiety to remaining bearing load of existing valves has risen, we tried parameter study about the stress distribution of corrosion deteriorated valve leaf by nonlinear finite element analyses using solid elements with 8 nodes As the result of investigation, about three kinds of valve leaf shape, stress distribution and failure condition concerning each corroded analysis model are clarified, and remarkable points in maintenance are described.

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In steel bridges, a lot corroded damage at girder ends has been reported so far. This damage mainly results from water leakage through expansion joints, and leads to corrosion of webs or columns at girder ends. As a conuntermeasure, we proposed repair/reinforcement method for corrded webs at girder ends using Carbon Fiber Reinforced Plastic (CFRP) sheet. In this research, we aim to study several topics relating to this method; optimum number of CFRP sheets, their repairing area and applicability of proposed shear strength prediction method. For this purpose, shear buckling tests for steel girders, which had damage imitating corrosion, were carried out. As a result, the followings can be concluded; 1) the same number of CFRP sheets should be attached on the web in the direction of tesile and compressive forces under diagonal tensile field after the number of CFRP sheets is determined so that the thickness of CFRP sheet converted to one of steel by the ratio of their Young's modulus is larger than corroded thickness. 2)When the web is only corrded near a supporting point, repair is not required because shear load-carrying capacity of the web changes little. 3) Proposed shear strength prediction method can be applicable even when the layered number of CFRP sheets is three ormore.

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This paper presents a repair method using steel cover plates and adhesive, in which the steel-cover plates are bonded by adhesive on the corroded surface of a steel plate. In this paper, the mechanical behavior and fatigue durability of this method were investigated through the cyclic tensile loading tests, changing load condition, plate size and corrosion surface made artificially by drilling. It is concluded from test results that the initial failure behavior was observed to start with the exfoliation of cover plate at the cover plate end, and the occurrence of exfoliation of cover plates was dominated by not only load amplitude but also by the upper load. Moreover, the failure criterion was also proposed as an empirical formula.

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Much corrosion damage has been observed in steel girders. In order to recover the performance of corroded steel members, we proposed a repair method using the UFC panels. The repair method has an advantage with corrosion resistance and simple workability. At first, Static tensile tests were conducted to clarify the basic performance of the bonding composite structures. Fatigue tests were also carried out to confirm the fatigue durability after the UFC panels were cracked. Shear loading capacity tests were conducted which the specimen was simulated the corroded I-girder shape repairing with the UFC panels. As a result, We clarify this recovery method has a sufficient repair effect.

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In this study, in order to investigate the effects of plate volume on load-carrying capacity and debonding behavior of the reinforced RC beams with submerged FRP plate, the static four-point loading tests were conducted taking material properties and mass of FRP plate as variables. Bonding capacity of the adhesive was also investigated comparing with the experimental results for RC beams reinforced with the same adhesive under the dry condition. From this study, the following results were obtained: 1) flexural load-carrying capacity of the RC beams can be improved by increasing plate volume with limitation; 2) plate debonding may be restrained by applying FRP plate with high Young's modulus and/or increasing axial stiffness of the plate; 3) FRP plate was debonded due to the peeling action of the tip of the diagonal shear cracks irrespective of treatment with/without sand coating and material properties of the FRP plate.

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In this study, fatigue strength of welded joints using a newly developed steel called Steels for Bridge High Performance Structures (SBHS) was investigated. Fatigue crack propagation tests with compact tension specimens were performed to clarify fatigue crack growth characteristic of materials. Then, fatigue strengths of welded joints using SBHS were investigated. These test results revealed that the fatigue performances of welded joints using SBHS are almost the same as those of conventional structural steels.

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It is important to estimate corrosion environment of steel bridges for an appropriate corrosion prevention and maintenance program. Estimation of environment has heavily depended on insitu observation and many data have been collected. However, versatile numerical approaches to this problem has not fully pursued yet. To this end, observation of airborne sea salt particles was performed with a standard low volume sampler (JIS Z 8814) beginning from April, 2013 to August, 2013 in the city of Nagoya and compared analytical estimation. A meso scale meteorological analysis employed here is WRF-Chem Ver. 3.4. Although WRF uses land use and terrain data based on USGS by default, the data is sometimes incorrect in Japan and yields inaccurate results especially for wind. Introduction of more accurate land use and geographic data supplied by the Geospatial Information Authority of Japan improves accuracy of basic meteorological data and therefore concentration of airborne sea salt particles. Other factors affecting accuracy of airborne sea salt concentration will also be discussed.

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Atmospheric corrosion of the steel surface of a bridge is largely due to salt spays generated over the ocean. The observed data indicate that the salt sprays first adhere to the steel, after which the extent of Cl⁻ on the steel surface increases; however, the mechanism by which these processes occur has not yet been investigated. Our research objectives are to examine the relationship of atmospheric Cl⁻ concentration with the extent of Cl⁻ adhering to the steel surface and to clarify the effect of surface winds on the extent of Cl⁻ adhesion. The results show that the extent of Cl⁻ adhesion is positively correlated with atmospheric Cl⁻ concentration and that the extent of Cl⁻ adhesion depends on surface winds.
Therefore, when estimating Cl⁻ on a steel surface, we must consider the atmospheric Cl⁻ concentration and the surface winds.

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In order to operate the efficient maintenance and management, it is important to predict the amount of sea salt particles adhered to each member of a structural surface. In this study, two different method s of the deposition to a structural surface are discussed. One focuses on the sea salt concentration flux normal to a structural surface. Another one is based on the physical behavior of each sea salt particle. Using these models, the amount of sea salt particles on each member of a structural surface is predicted with the meteorological observation data. While the tendency of distribution is in good agreement between the predicted and the observed value, there needs further improvement to get more accurate results.

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For investigating corrosinon characteristics of welded part of structural steel and paint coating deterioration behavior on it, a series of accerelated exposure tests with combined salt water spray cycles were carried out. The degree of corrosion of welded part without any coating was smaller than that of base metal part because of advantageous chemical compositions in anti-corrosion. Altough the deterioration from paint defect along the weld toe was larger than that from the cross scribe paint defect in the early stage of the tests, the speed of paint deterioration was slower around the weld toe rather than that around the cross scribe line.

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Recently in seismic retrofitting or strengthening for not only ordinal steel bridges but also weathering steel bridges, new steel members are connected by high strength bolts. But it is little known that slip coefficient and treatment method of contact surfaces of the weathering steel bridge and the new ordinal steel members. Therefore to show the slip coefficient of the high strength frictional bolted joints with two different treated contact surface between the weathering steel and the ordinal steel, slip test was conducted. From the slip test, it was found that the contact surface of the weathering steel is treated by scouring the rust off as much as possible and the contact surface of the new steel members is treated by aluminum spray to obtain higher slip strength.

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Maurer expansion joints, one of the modular types, have been used in Japan since 1980s. They were originally developed in Germany, and were then introduced to Japan. Later the parts of the joints were modified by Japanese supplier. It had weld joints between middle beam and support beam. The function of the middle beam is to support wheel loads, and that of the support beam is to transfer the load to girders through lower bearings. Since the expansion joints are subjected to large number of wheel loads, fatigue assessment is essential. Fatigue tests were carried out with newly designed fatigue testing machine. It used a motor with eccentric mass to vibrate the specimens. Fatigue crack initiation and propagation behavior were specifically monitored, of which the information can be used for periodic inspection of the joints in the field.

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Fatigue strength category of out-of-plane gusset welded joint was determined based on large number of previous fatigue tests and is categorized with gusset length. However, the variety of the joint size of specimens used in previous researches is very limited and the size is much smaller than the joints in large structures like steel bridges. In this study, stress analyses with out-of-plane gusset welded joint models having large variety of joint size like from small joint specimen to joint in steel bridges were conducted and size effect on fatigue strength was discussed. In addition, the fatigue strength of joint having large out-of-plane gusset is analytically evaluated.

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Many researches about the influence of weld misalignment or angular distortion have been made and some kinds of regulations, such as a allowable misalignment, have specified in the several fields. In Bridge Highway Standard in Japan, an allowable misalignment is specified for butt weld joint, and this weld quality (accuracy of member assembling) is controlled/inspected during bridge fabrication. However, there is no standard for the misalignment in other types of welded joints in bridge structures. In this study, focusing the misalignment occurred in cruciform weld joint, the measurement of the actual misalignment occurred in bridge members was conducted in several bridge factories and the influences of the misalignment on fatigue is analytically evaluated.

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The authors focused on the high strength bolted friction grip joints with countersunk head which can finish the surface of the connection plate flat smoothly and prevent from functional decline due to corrosion. In this study, in order to examine the effect of over-sized holes on the slip resistance and the yield resistance of the friction type of high strength bolted connection. The tensile tests have been performed on the bolted connections in consideration of slip to yield resistance ratio. As a result, following conclusions have been obtained. The slip resistance does not depend on the hole diameter.

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The authors focused on the high strength bolted friction grip joints with countersunk head which can finish the surface of the connection plate flat smoothly and prevent from functional decline due to corrosion. In this study, in order to examine the effect of the partial contact on the slip resistance and ultimate strength including bearing capacity with countersunk head bolts, we have performed on the tensile tests for bolted the bolted connections with the partial contact.Based on the experimental results, it has concluded that the slip resistance and ultimate strength does not depend on the partial contact.

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In this study, focused on the ultimate state of high strength bolted joints, design methods of specifications are summarized and slip tests of joints have been carried out. The specimens of tests have bolts with bolt axial force and without that, and some edge distances. The results of the tests are discussed focused on the deformation performance of the joint and the energy absorption of the external work, such as earthquake loads. Reasonable design formula for the shear strength of edge distance is introduced. It is found that bolt axial force makes deformation performance of the joints small.

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The high strength bolted frictional joints are frequently used for repair and strengthening works of steel bridges, such as patch plates with epoxy resin. But it is not clear how adhesive might influence on slip resistance of the joint. Consequently the practical design code does not generally consider increase of slip resistance due to bolt axial force and adhesive effect. In order to clarify the relationship between the location of concavities and bolts, and the influence of the depth and the number of concavity on slip resistance, a slippage test of the high strength bolted joints with adhesive on some concavities has been carried out. It is concluded that the high strength bolted joints with adhesive can be designed as the high strength bolted frictional joints.

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Recently, it has been shown the pull-out strength of deformed steel bar whose pilot hole diameater was 14mm was as strong as the pull-out strength of lag screw whose poilot hole diameater was 15mm. From this result, general purpose utilization of deformed steel bar to wooden civil engineering structures is considered. Therefore, in this study, in order to confirm wheather it is possible to use deformed steel bar for actual civil engineering structures, we made the real-size specimen of all wood type wooden check dam utilizing only deformed steel bar whose pilot hole diameater was 14mm, and conducted horizontal load test. We also compared the performance of the specimen utilized lag screw whose pilot hole diameater 15mm.

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After the 1990s, modern timber bridges based on innovative ideas have been started to construct. Because of its high durability, a large number of them were made of Ekki which is a hardwood native to West Africa. However, a considerable number of them were decayed under Japanese high temperature and humidity. The aim of this study is investigating the ultimate behavior of decayed Ekki members. Test specimens were obtained from the arch bridges which was servicing for 13 years and taken away. Bending and pin compression test were carried out. Useful information was obtained for diagnosis and maintenance of bridges.

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The reason for fracture of many stirrups in a bridge pier suffering ASR damage is discussed. Evaluations are conducted for the distribution of damaged stirrups in axial and cross sectional direction of the beam, for the bending radius and generated cracks of used stirrups. As the results, it is confirmed that used stirrups can produce great initial cracks easily. Thus, the progress of initial cracks is thought to be the reason for fractures of many stirrups. Further, the random distribution of damaged stirrups is estimated to be caused by the great scatters in generating of initial cracks.

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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 degradation in specimens at outdoor environment. Rebars according to the old specification before 1985 have been used in the specimens. Due to impact from ASR expansion, the progress of cracks was observed in bent part of rebars; the crack length being 31.5% of the rebar diameter was generated. Comparison for shapes of progressing cracks in stirrup with shapes of initial cracks due to bending process was conducted, from which, authors give evaluations for progressing characteristics of rebar cracks induced by ASR.

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Freezing and thawing tests of the reinforced concrete beam specimens without AE and water-reducing admixture were carried out. The shear strength and the dynamic elastic modulus of the RC beam specimens were decreased by freezing and thawing action. From the experimental results, the shear strength of RC beam specimens was fairly evaluated when the decrease in the tensile strength of concrete damaged by freezing and thawing action and the increasing shear strength by the stirrup according to the truss theory were considered. However, the shear strength of the stirrup was overestimated when the relative dynamic elastic modulus of the RC beam specimen is less than 60 %.

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This paper is a study for RC Bridge, which has been severely degraded by salt damage during 56 years at the west coast of Okinawa. For the Load Testing we removed girders from the damaged bridge and studied the degree of deterioration from salt damage with assessed the residual strength. We compiled the results using a salt damage map, which clearly showed a high degree of deterioration. According to the Neutralization Material Test and Salt Amount Test, it was clear that the main cause of the deterioration was airborne salt. In addition, as a result of the Static Loading Test the experimental value of the bending strength of the RC girder was greater than the calculated values. Therefore, results show that, with the current level of deterioration, there is no significant reduction in the yield strength of the RC girder.

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By conducting cyclic loading tests using full-scale specimens with image based measurements and numerical studies, we evaluated the effects of cracking damages caused by earthquake and the following reinforcing steel corrosion on load carrying capacity of an RC box-culvert. Despite of initial cracking damages, the maximum strength of corroded specimens slightly decreased, although average corrosion ratios decreased up to approximately 10%. This was because the sectional forces were redistributed after cracking. However, in the cases of that the initial cracking damage levels corresponded to yielding of the reinforcing steels the local damages became larger in the loading pass of after maximum strength because of steel corrosion.

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The plastic hinge length is one of the important factors to evaluate the ductility capacity of reinforced concrete bridge columns that fail in flexure at the bottom under seismic loading. Since it is known from experimental studies that the plastic hinge length has strong correlation to the buckling length of longitudinal reinforcement, a series of FEM analyses was conducted to simulate the buckling behavior of longitudinal reinforcement of reinforced concrete bridge columns under the seismic loading. In the analyses, the effects of idealization of resistance of cover concrete and transverse reinforcement against buckling were investigated. Based on a regression analysis of the results from FEM analyses, a simplified equation to evaluate the plastic hinge length was proposed.

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The purpose of this study is understand the deformation performance of the RC bridge pier using the combination of high-strength rebars SD390, SD490 and high-performance material. From the conduction of cyclic loading test on the modeled specimen, damage form, bearing capacity and deformation performance have been evaluated. As a result, great difference is not observed between the damage forms of specimen using high-strength rebars and the specimen arranged by the commonly used rebars SD345. It is possible to make RC bridge pier with great high bearing capacity and deformation performance by using the combination of high-performance material and high-strength rebars.

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The maintenance of the steel bridges is considered to be problems recently. Therefore, in this study, the steel bridges are composed with concrete members. The noises of the steel bridges are reduced by these means. In addition, the stiffness increases from the bridges of only steel members. The remainder life of the structure is extended by this effect. These effects are confirmed by the experiments.

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The continuous composite girders are frequently used for railway and roadway bridges. The examination of the design techniques for internal forces on the section is not mainly carried out, and so these techniques have not been unified. The internal forces include the shrinkage, difference of temperature and creep. In this study, the continuous composite girder is designed with several calculation techniques for internal forces. In addition, each design results are compared with FEM analysis.

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The slip strength of perforated rib shear connector is increased by confined effect of concrete. Confined effect is generated by expansion of concrete. But when Load acts to the PBL, in elastic range, concrete of PBL is not expanded. So we think that volume expansion of concrete is occurred by collapse of concrete. At first, top of the concrete, which located in the PBL, was collapse by stress concentration. And then, concrete collapse made unevenness on interface. The slip strength occurred from friction with confinement force to unevenness interface.

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In this paper, we conducted static push-out simulations of perfobond shear connectors (PBL) using SPH, and validated their static strength and failure mechanism. In order to express hydrostatic pressure dependency of concrete in the analysis, The Drucker-Prager criteria with plane cap model and damage concept caused by compression fracture were applied. Appropriateness of constitutive model for concrete was confirmed on their static behaviors comparing with triaxial compression tests. Secondly, static push-out test simulations were conducted using this model. As a results, as well as experimental results, it gave the influence of transverse reinforcement to shear force of perfobond shear connectors was examined.

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In this paper, newly developed hybrid structural footing, in which steel grid girders are embedded, is explained in order to replace existing piers for widening double-deck superstructures. The behavior and mechanism of the hybrid structural footing under the static loading tests are described in details. It is confirmed in the static loading test that the load bearing capacity of the hybrid structural footing is around three and a half times of the level II earthquake load. Authors also carried out three dimensional nonlinear FEM analyses and obtained the relationship between loads and displacements, distribution of concrete cracking and stress on the steel grid girders. It is found that the analyses could simulate results of the experiments qualitatively.

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Authors devised the joint of composite steel girder and PC girder using shear connecting method. In this paper, simplified design methods of shear connector located in the joint are proposed and verified through loading test of the 1/2 scaled model together with three-dimensional nonlinear finite element analyses. Further, it is proved that new shear connecting method using mortal filled steel tube inserted in perforated steel plate are available for shear connector at web steel plate of joint.

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A connecting method by means of studs was generally used for connection between steel girder and concrete abutment for joint-less bridge structures. To evaluate the seismic performance and failure mechanism of joint-less bridge structures, it is important to evaluate the seismic behavior of the connection under seismic loading. Therefore, a cyclic loading test for a connection with headed studs, which followed by a FEM analysis, was conducted. It is found from the test results that damage of the connection was limited under the level 2 ground motion, which ensured capable of recovering bridge functions within a short period. From the FEM analysis, detailed failure mechanism due to bearing pressure under punching shear failure was investigated, and structural details were proposed to prevent the punching shear failure.

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A strengthening method for welded joints in aged steel railway bridges using Glass Fiber Reinforced Plastic (GFRP) plates, rubber-latex mortar, and rapid hardening concrete and reinforcing bars is introduced in this paper. The purpose of the present study is to investigate the performance of the welded joints before and after strengthening. Totally two joints, designed to sustain positive and negative bending moment respectively, were used in the experimental study. The static loading tests were performed to confirm the effects of the present strengthening method. Moreover, three-dimensional FE models were built to make a numerical study on the present strengthening method. Load versus deflection relationship and sectional strain distribution were measured and compared between the original joints and the strengthened joints. Both experimental and numerical results indicate that the present strengthening method can greatly enhance the stiffness and reduce the stress levels of the welded joints, resulting in the extension service life of old railway bridges. Besides, influence of bond strength was investigated, and the effect of the rubber-latex mortar was confirmed.

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The purpose of this paper, while steel framed reinforced concrete girder is popular for an over-road bridge restricted by under a girder, is to investigate and verify the practical application of new structure with which reinforced concrete roadbed applied to girder's structural members by focusing on the roadbed used as non-structural members and executing tentative design and finite element structural analysis.This paper examines flexural strength and the influence for cracking for overhang RC slab on tension side by cyclic vertical loading test. This paper attempted to reduce the weight of a bridge by unification of reinforced concrete roadbed and girder. As a result, this paper indicated the applicability of the new structure to realize lower girder height through testing and analysis.

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For seismic design under large-scale earthquakes, unseating prevention systems at the supports of railway steel bridges become large size and sometimes cannot be installed in the limited space. To enable a compact-sized device, authors proposed a concrete encased steel frame (SRC) stopper. However, the evaluation method of its capacity is not clearly established. In this study, the failure mode and the capacity against lateral force of the SRC stoppers were clarified through static loading tests. To evaluate the capacity of the inserted area into RC pier, stress behavior was discussed using 3-D finite element analyses. Considering these results, an evaluation method of shear load-carrying capacity of SRC stoppers including the inserted area was proposed.

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Based on the cyclic-loading experimental tests on edge-reduced footing with couple piles, 3-d fem analysis was performed. According to the evaluation result, it was found that the strain of reinforcing bars on the under surface of footing and the cracks increased in both the experimental test and the analysis. Besides, the proposed failure surface was similar to the failure surface of normal punching shear failure. Therefore it was considered that failure similar to the horizontal punching shear occurred to edge-reduced footing in this experimental test.

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In order to reduce the earth pressure applying to bridge abutment, there is a case to use the EPS as backfill of bridge abutment. However, there are various uncertainties about seismic behavior of bridge abutment and the EPS backfill. In this study, we conducted a series of dynamic centrifuge model tests for the purpose of evaluating the dynamic response characteristic of each structure. As an experimental result, it is found that earth pressure during earthquake acting on bridge abutment in the case of the EPS backfill is larger than the case of the normal backfill, at the position of the reinforced concrete slab placed in the EPS.

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In an earthquake caused by an active fault, a gap of the fault may reach several meters. Therefore, water pipelines across a fault must be designed carefully. However, the design method of ductile iron pipes with earthquake resistant joint buried across a fault is not established. In this study, we analyzed the behavior of ductile iron pipes with earthquake resistant joints buried across a fault and studied the behavior of joints every dip of a fault. In addition, we verified the analysis results through the experiment using the actual pipes.

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In this study, in order to investigate the impact resistance behavior of the flexural reinforced RC beams with AFRP sheet, falling-weight impact tests were conducted taking with/without bonding AFRP sheet and height of a falling weight as variables. From this study, the following results were obtained: (1) impact resistant capacity of the RC beams can be upgraded by reinforcing with AFRP sheet; (2) dynamic load-carrying capacity and maximum input energy for the reinforced RC beams with AFRP sheet are 1.2 times greater than those of not reinforced ones; (3) energy absorption capacity of the RC beams under impact loading are similar irrespective of with/without reinforcing with AFRP sheet; and (4) AFRP sheet bonded onto the tension side surface of RC beam under impact loading tends to be ruptured more easily than the case of static loading.

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In order to investigate impact response behavior of a three-layer absorbing system (TLAS) with soil cement at the ultimate state and to develop a design concept of the system, falling-weight impact test was conducted varying impact velocity of the weight. From this study, it was confirmed that the loading level can be categorized into two classes: 1) Level 1 stage in which the geotextile can widely disperse the impact force and EPS block can effectively absorb the impact energy; and 2) Level 2 stage in which the impact force was locally concentrated in the loading area due to geotextile being broken and safety of the protection wall should be confirmed.

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In this study, in order to investigate an applicability of the three-layered absorbing system (TLAS) with soil cement to rockfall protection walls, large-scale falling-weight impact test were carried out using 5 and/or 10 ton weight. Also conducting dynamic response analysis of the full-scale rockfall protection wall with the TLAS inputting time history of the transmitted impact force obtained from the test results, the damage level and stability of the wall were verified. The following results obtained from this study were as follows: 1) TLAS proposed here can effectively absorb the impact force with an impact energy of E = 1,200 kJ ; and 2) rockfall protection walls with TLAS proposed here can be applicable for falling rocks with the impact energy of E = 1,200 kJ.

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In order to establish a performance-based design procedure for rock-sheds, material properties of the cushion layer in situ were investigated and large-scale falling-weight impact test for gravel cushion which is applied for many existing rock-sheds was conducted varying thickness of cushion material and falling high of the weight as variables. The results obtained from this study were as follows: 1) not only sand cushion but also gravel cushion were used for many existing rock-sheds and the cushions were under strongly compacted; 2) in the cases of same impact energy but different mass of weight, those penetration depths of weight were a little different but maximum impact forces were almost the same each other; and 3) maximum weight and transmitted impact forces in the case of gravel cushion were two to four times greater than those in the case of sand cushion.

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In this study, sectional design of full-scale RC rock-shed for falling-weight impact test was carried out assuming impact energy of E = 100 kJ. The ultimate load-carrying capacity and deformation characteristics of the model for each impact level were predicted by means of a 3D dynamic frame analysis method. From this study, the following results were obtained: 1) designing the rock-shed following the allowable stress design method, each thickness of the slab, wall, and columns was determined so as to be 70 cm; and 2) based on the numerical analysis results of the rock-shed in the case of an impact energy of E = 3,000 kJ, it will be predicted that the slab and upper part of the columns may locally reach the ultimate state with compressive concrete failure mode.

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In order to accumulate basic knowledge for establishing the rational performance-based impact resistant design procedures of RC rock-sheds, the consecutive falling-weight impact test of full scale RC rock-shed with 90 cm thick gravel cushion was conducted. In this test, impact response behavior of the rock-shed from the elastic region was investigated by falling-weight impact test. From this study, following results were obtained: 1) Lame's constant of gravel cushion used as cushion material may be about 4,000 ∼ 10,000 kN/m², it may be influenced by the compacting intensity and the flexural stiffness of the roof slab at the loading point; 2) in the case of loading at the central position, sectional forces may be also subjected to the roof slab, side wall and column for both sides; and 3) in the case of edge loading, sectional forces tend to be larger than the case of central loading.

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Cushioning materials, such as sand cushion placed on rock sheds, have attracted attention as construction devices that can effectively disperse and reduce rock fall energy before rocks collide with rock fall protection structures. To support performance-based designs for rock fall countermeasures, the present study estimated rock fall behaviors and impact forces using 2D discrete element method (2D-DEM). The propagation of impact forces in sand cushion with different masses and velocities of rock fall were investigated. It was discussed that comparison between effects of mass effect and impact velocity on the impact behaviors, the mechanism of impact forces in sand cushion. Even under the equivalent impact energy, the maximum impact forces increase with incresing mass.

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Although pocket-type rockfall protective nets are more economical and easier to install, the amount of rockfall energy they can absorb and the locations where they can be implemented are limited. Because of this, in recent years, modified pocket-type rockfall protective nets with built-in shock absorbers have been developed to increase their ability to absorb rockfall energy. This study was conducted in order to determine the effective range of implementation for a modified pocket-type rockfall protective net, and to test the net's reaction and energy absorption capabilities upon the introduction of rotational energy closely approximating the actual behavior of a falling rocks. These tests were conducted on a steep and real slope which a full-scale weight rolled down, and utilized protective nets fitted with two types of shock absorbers, the capabilities for which had been confirmed in previous free-fall weight impact tests.

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This paper presents an analysis approach of full scale falling rock protection net by using 3D-Distinct Element Method. In the collision experiment carried out in advance, the dynamic deformation process of net is recorded by video and high speed camera, and the tensions of anchorage wire-ropes are measured by load cells. In 3D-DEM, the steel net and wire ropes are modeled by using cylindrical shape elements. The reproducibility of the analysis results are examined by comparing with the experimental data. Energy transition is checked from viewpoint of a design code validity. And they show good agreement each other.

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