In applying various steel-concrete composite structures and hybrid structures, it is difficult to conduct the entire model test of the structure. Therefore, behaviors of the actual structure are predicted by conducting the scaled model test, the partial model test or the numerical analysis. Then, the focusing points such as the behavior of the shear connectors are confirmed in the scaled model test or the partial model test. The element test which investigates the behavior of the shear connector is also conducted. However, it is not clarified that the behavior of the shear connector in element test can simulate the one in the actual hybrid structure and to confirm this point is the problem. Here, the experimental results of the steel-concrete composite beam and corresponding element test is explained in detail. In particular, the relation between the beam test and element test focusing the behavior of the shear connector is also investigated.

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 Current problems of the composite structures in the architectural engineering field, which has been analyzed through the activity of Steel Concrete Composite Structures (SCCS) steering committee of Architectural Institute of Japan (AIJ), are described. The utilization situation of the composite structures in Japan and studies on the concrete encased steel (CES) structures and the composite structures using FRP materials which are new proposed composite structural systems are also introduced.

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 A bridge inspection path using GFRP trussed girder has been developed for the highway bridges. The innovative feature is the introduction of a trussed-girder-type with a sandwich slab panel made of pultruded GFRP and urethane foam. In study, in order to make improvements and more reasonable, the panel joints are reinforced by GFRP angle profiles, the distance between the panel joints is extended and the thickness of slab is reduced in the bridge inspection path using GFRP trussed girder. The several experimental studies were conducted using the real size model. The serviceability of deflection limitation and vibration were investigated and there was no problem for the serviceability. In addition, the load carrying capacity of the real size model was examined by four-point bending test and sufficiently high against design load. Therefore, the developed bridge inspection path using GFRP trussed-girder-type with a sandwich slab panel have the applicability for practical use.

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 The aim of this study was to elucidate the degradation mechanism of post-installed adhesive anchor in alkaline solution and to establish a method for evaluating its alkali resistance properties. We investigated the mechanical properties of the adhesive anchor in potassium hydroxide (KOH) solution with reference to ACI 355.4-11 standard. Changes in chemical structure of the adhesive in the alkaline solution were analyzed with infrared (IR) spectroscopy. The results indicated no significant deterioration in the bond strength of the adhesive after 4000 hours of immersion in KOH solution at 40°C. However, unsaturated polyester resin, a component of the adhesive anchor, showed hydrolysis in KOH solution. The hydrolysis reaction was found to accelerate with increasing temperature of the alkaline solution and progress from the surface to inside with increasing time of immersion.

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 The slip behavior and failure properties of perfobond rib shear connector (PBL) were investigated by various loading tests. Static push-out tests were conducted under several different restraint conditions to examine the influence of restraint conditions on the shear force-slip relation. Observation of cracked surface in perforation after the loading tests indicated that the reversal cyclic tests accelerated smoothing of rough crack surface. The fatigue lives obtained from identical loading condition were scattered in 10000 times different. The fatigue limit diagram of the PBL was formed based on both the past and our experimental results. The observation of cracked surface in perforation after the loading indicated that the concrete dowel can be broken along two crack plains, even if thickness of PBL is 6.5mm thin.

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 The ultimate moment of resistance of the composite beam with the steel beam and the reinforced concrete slab generally depends on the classification of the cross sections. JSCE Standard Specifications for Hybrid Structures also use the classification of the compact, non-compact and slender cross sections to calculate the ultimate moment of resistance of the composite beam. However if we can calculate the ultimate moment of resistance of the composite beam regardless of the classification of the cross section, more rational proportion of the composite beam can be potentially designed using constitutive material performance as possible as we can.
 In this research, we conduct the static test of the composite beam specimens which is the beam with the compact cross section and we attempt to confirm the load carrying behavior of the specimen in detail. In this case, two types of the specimens with studs differently arranged at equal intervals are employed and we investigate especially the sequence of the damage of the steel beam and the concrete slab such as the yielding of steel and the compressive failure of concrete.

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 A part of newly constructed taxiway in Narita international airport, steel-concrete composite deck bridge is adopted where the taxiway strides over existing road. Taxiways those have bridge style are rare in the world and the design method for the taxiway bridge is not clearly established at this moment. Thus, in addition to well-used design method of road bridge, FEM analysis and punching shear experiments with full scale specimens were carried out to verify the safety of the bridge and concrete slab. After completion of the construction work, loading tests by real aircraft were also executed to verify the distributions of stresses in the slab and safety of the bridge. Gauges and thermocouples were installed in concrete slab and on the girders at construction stage. Up to the present, continuous measurement is ongoing using the gauges and monitoring systems and the behavior by aircraft taxiing were measured. This paper introduces the taxiway bridge as one example of composite structures and describes some acknowledges from the experiments and studies.

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 Sanriku Railway Haipesawa bridge is a new bridge alternative to the old one extensively damaged by the tsunami of the Great East Japan Earthquake. The new bridge is a new type bridge (GRS integral bridges); integral bridge with geosynthetic reinforced soil (GRS) abatement.
 Consider of the crossing conditions at the Haipesawa river, we applied steel-reinforced concrete (SRC) through girder-type. We applied anchor beam type considering FEM, to the method of fixing girder and abutment,
 Haipesawa Bridge, length 60m, is the longest GRS integral bridges, so seismic design model is connected integral bridge and abatement. And we managed the bridge construction understanding the behavior of the changing structural systems; steel girder erection and concrete construction.
 This paper is the report based on the result of Haipesawa bridge design and construction.

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 It is known that FRP will cause a creep by a sustained load. For this reason, it is important to consider the creep for the design of the structure about the connection part of the FRP and FRP member. Here, in the connection part of the FRP, the friction grip and the bearing connection were selected. For glass fiber laminated material and carbon fiber and glass fiber compound laminated material, the creep data about the bolt axial tension and the creep data based on bearing force were obtained. Furthermore, for glass fiber laminated material, the creep limit data based on bearing force and the bending creep data of FRP member were obtained.

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 A perfobond strip is one of the shear connectors generally used in steel-concrete hybrid structures. We have conducted the push-out test of the perfobond strip specimen whose steel plate with the perforation was embedded in the concrete block. However, it is not clear whether the results obtained from the above experiment reproduces the one of the perfobond strip in practical structures or not. In this research, we also conduct the push-out test of the perfobond strip specimen where the steel plate with a perforation is welded to the steel base plate and constructs T-shaped section or the cruciform section as used in the practical structures. In order to predict the stress transmission between the steel base plate and the perfobond steel plate, and the force distribution along the height of the steel plates, several strain gages are attached to the steel plates in the specimen. As a result, it can be seen from the experiment that the various types of the specimens employed here have different shear force-relative slip relations and shear resistances, and the horizontal stress as well as the vertical stress is produced in the perfobond steel plate.

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 This paper shows the evaluation method of damage and failure of concrete for composite member such as steel-concrete composite slabs and foundation of wind turbine. The second strain invariant of deviatoric strain tensor and consumed strain energy averaged over certain region calculated from local strain were applied for the damage assessment. Owing to their complexity shapes of composite structures, FE-modeling was often required very small mesh division locally. Then, it is important that to reduce influence caused by mesh definition on assessment of output and ultimate limit state. As a result, those nonlocal damage index can assess the failure process for several types of composite structure where the damage of concrete is dominated. It was revealed that these index could evaluate the safety of composite structures by nonlinear FE analyses.

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 Integral bridge with geosynthetic-reinforced-soil (GRS integral bridge) is a method of construction to integrate abutments and GRS with a bridge superstructure. Because of its structural system, i.e. highly statically indeterminate structure, it is concerned that the bridge with longer span may have larger influence on crack occurrence, caused by temperature deformation and shrinkage of concrete. This study aims to observe the time-dependent behavior of large-scale GRS integral bridge. For this purpose, authors carried out a long-term measurement of displacement, strain, etc. of GRS integral bridge with 60m bridge length.
 This paper describes the measurement results of 1.5-year measurement and the observed knowledge from the measurement results. As a result of the measurement, it was found out that the deformation behavior of the bridge by the shrinkage of concrete is relatively small and that by the temperature deformation differs in summer and winter, affected by the degree of constraint by the GRS. Considering these results, the time-dependent mechanism of resistance of the GRS integral bridge was discussed.

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 There are high demands on existing railway reinforced-concrete (RC) viaducts to improve not only seismic performance and durability but also utilization of space under the viaducts. Authors have proposed a method of column relocation in which new concrete-filled steel tubular (CFT) columns are installed and existing RC columns are removed. However, the structural system of the viaduct is changed by the column relocation and has columns with largely different stiffness and load-bearing capacity.
 The purpose of this study is to observe the seismic behavior of the column-relocated viaducts, focusing on the effect of having frames with different stiffness, load-bearing capacity and deformation capacity. Authors carried out a series of dynamic response analyses and static push-over analyses with 3-dimentional frame models. As a result, it was found that the viaduct with different frames shows a small reaction displacement in 3-dimensional dynamic analysis comparing with the result of non-linear spectrum method using static push-over analysis results. This is because of the cancellation of the displacement components in each frame that have different vibration properties. For this reason, it is possible to calculate the response displacement of the column-relocated viaducts in safe side. On the other hand, the section forces, i.e. bending moment and shear force, increases in dynamic state. Based on these results, authors proposed a simple calculation method using 2-dimentional static push-over analyses for the design of column relocation.

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 Committee on Hybrid Structures (JSCE) published the Standard Specification for Hybrid Structures - 2014. The Standard Specification consists of four parts, that is, “General Principle”, “Design”, “Construction” and “Maintenance”. The Standard Specification covers the steel-concrete hybrid structures and FRP structures. “General Principle” part specifies basic rules for practicing design, construction and maintenance in close cooperation with each other. “Design” part, “Construction” part and “Maintenance” part are composed of two parts, that is, Standard and Specification. Standard part specifies the principle rules of hybrid structures so as to respond the design, construction and maintenance of the new type hybrid structures, and Specification part also specifies the practical treatment for the proven hybrid structures.

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 Recently, in Japan, the steel-concrete composite slab which is connected between concrete and steelplate with shear connector aiming at having high durability performance, reducing construction period and so on is adopting widely and its numbers are increasing remarkably. However, there are no uniform design and construction guidelines concerning steel-concrete composite slab.
 Therefore, the subcommittee formulated guidelines for steel-concrete composite slab including design, construction, inspection and maintenance. This guideline is described based on performance-based design method employed in the standard specifications for hybrid structures published in 2015 by JSCE.

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 In order to derive an eminent performance of steel-concrete hybrid structures, it is required to transmit the stress adequately between steel material and concrete material, or between a steel member and a concrete member. A part referred to as a shear connector is usually employed in steel-concrete hybrid structures to achieve stress transmission and the shear connector provides stress transmission by restraining the relative slip between steel and concrete. Therefore, the shear connector is a key part in steel-concrete hybrid structures.
 The extensive research works on the shear connectors, in particular the headed stud, the perfobond strip and the plate shape shear connector were conducted in Subcommittee on Performance Evaluation of Shear Connector in Steel-Concrete Hybrid Structures which was set up in Committee on Hybrid Structures JSCE. This paper shows the outline of the report which was summarized of the results obtained through the research works.

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