A simple and rational connection for hybrid structures, which does not require shear connectors or steel reinforcement, has been developed. A material whose tensile strength is high is applied to closed-box structure, members to be connected is then inserted through hole of the closed-box structure, and finally a material which can transfer compression is filled in the closed-box structure. This study discloses that concrete-filled steel box (CFSB), as the developed connection, possesses excellent structural performances and that CFSB can be applied to an actual bridge as abutment after conducting the loading test of specimens with a half scale, execution test of specimen with the real scale, and loading test of the real bridge. Furthermore, concrete constitutive model for compression softening with consideration of confining effects was proposed, and then numerical experimentation by FEM with the proposed constitutive model was conducted to show the effects of inserted length of steel tube (as connected member), ratio of shear force to flexural moment at the beginning of steel tube insertion, steel tube cross-sectional size, steel box size, and concrete strength on the ultimate strength of CFSB under flexural moment.

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 A perfobond strip is widely used as the validated shear connector in the various steel-concrete hybrid structures and many researches on the perfobond strip are also conducted and the design formula for the perfobond strip has been already proposed by some researchers. However, the shear resistance evaluated by these design formula does not successfully correlate with the experimental ones. In this research, the effect of the concrete block proportion and of the thickness of the steel plate on the shear resistance is investigated for the perfobond strip without the penetrating rebar. The fundamental experiment is also conducted to investigate the effect of the crack of the filled concrete in the perforation, interlocking action of the aggregate and the restrained force on the shear resistance of the perfobond strip, paying attention to its shear resisting mechanism. And we attempt to predict the shear resisting mechanism of the perfobond strip without the penetrating rebar. Finally, applicability of the design formula of the perfobond strip without the penetrating rebar proposed by authors to the extensive experimental data by other researchers is confirmed.

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 Recently, infrastructures made of glass fiber reinforced polymer (GFRP), which have high durability performance and are cheaper than the cost of other fiber reinforced polymers have been constructing in Japan. Because elastic modulus of GFRP is lower than that of steel material and the deflection of structure made of GFRP becomes larger, the structural section area of GFRP members becomes larger than that of steel members. In this study, bending tests and theoretical consideration were carried out to study flexural behavior of the steel and GFRP composite girder that were laminated steel plates with many holes called punching metal to increase the bending rigidity of GFRP girders.
 From these results, it was seen that the bending rigidity of the composite girders were varied due to the differences of kinds of punching metal and laminated position of the metal. And the laminated positions and the kinds of punching metal to increase the bending rigidity of the composite girder were found.

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 There has recently been a requirement for constructive structures to be efficiently maintained and managed. Specifically, steel bridges for railways, many of which are past their design service life, often continue to be used as matters now stand. As another big issue for steel bridges in railways, on the other hand, there is a subject on how to suppress acoustic noises as well as the life prolongation. Therefore, this research offers a new composite-revamping method for railway bridges by assuming composite remodeling process of existing steel bridges having no specific fissure damages or serious corrosions and effectively making use of relatively new materials to it. Furthermore, it was confirmed by the construction tests using actual steel bridges that the switching work can be performed well even under strict limitation. Moreover, effects of noise reduction and improved stiffness were further confirmed through hammer-impact tests (vibration-measurement tests) and loading tests in order to prove the efficacy of the composite remodeling.

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 The slip strength of perfobond strip is effected by several confinements restraining concrete fracture around a hole. This paper presents the several confinement factors in slip tests and a method evaluating the ultimate slip strength caused by concrete fracture. It is concluded that the confinement factors are the concrete covering of the connector, the reinforcing bars perpendicular to the connector plate such as rebars set through or near the hole of the perfobond strip, etc., and also the friction force between specimen and test bed in the case of push-out tests. The slip strength of perfobond strip can be evaluated accurately by the method proposed herein which takes each confinement effect into account.

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 If the axial compressive force as well as the shear force is applied to the interface between flanges of the steel beam and the concrete which is connected by headed studs, shear force or shear force-slip relationships is different from the case where the axial force is not applied is the obvious. In this study, push-out tests of headed studs are conducted with axial compressive force controlled by using hydraulic jacks, and shear capacity and shear force-slip relationships of such studs under both shear force and axial compressive force are investigated. And, the shear capacity formula which is used the coefficient that take into account the influence of axial compressive force is proposed.

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 The Standard Specifications for Hybrid Structures of the Japan Society of Civil Engineers indicate formulas, derived regressively from experimental results obtained in Japan and abroad, for calculating the shear capacity of perfobond shear connectors (perfobond leisten, or PBL) in the case where there is penetrating reinforcement and the case where there is no penetrating reinforcement. These formulas are not applicable to concrete that has a compressive strength exceeding 60 N/mm².
 As with headed studs, it has been standard practice to verify the shear capacity of PBLs by conducting push-out tests. It is generally said, however, that the shear capacity of PBLs is affected by the constraint of concrete blocks, and the magnitude of such constraint has not been determined by conventional testing.
 In this study, focusing on the use of PBLs to join high-strength concrete having a compressive strength higher than 100 N/mm² and steel, a number of experiments parameterizing constraining force and compressive strength were conducted. In the experiments, constraining force was applied directly to the test specimen by use of hydraulic jacks. The experimental results have shown that the influence of constraint on shear capacity is significantly large even when high-strength concrete is used. A shear capacity formula that takes into account the constraining effect and the effect of concrete strength derived from the experimental results is also proposed in this study.
 Loading tests were also conducted using hybrid girders made by joining together high-strength concrete and steel by PBLs to evaluate the shear capacity of PBLs. Constraining force was calculated from concrete strain distribution, and the result was substituted in the proposed formula to calculate shear capacity. The shear capacities thus calculated were 10 to 20 percent greater than the measured values.

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 The Great East Japan Earthquake of M9.0 hit the Tohoku area on March 11, 2011. The huge earthquake followed by tsunami caused tremendous casualties and damage of structures across the Tohoku and Kanto areas.
 JSCE committee on hybrid structures dispatched the 1st survey subcommittee to Tohoku area, Iwate, Miyagi and Fukushima prefecture.
 This survey of hybrid structures in areas not affected by the tsunami confirmed that serious damages in hybrid structures were not seen and seismic retrofit work to prevent the collapse of concrete structures had been effective.
 This report has described the problems and possibilities of hybrid structures against a huge earthquake and tsunami which will happen in the future.

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 Generally, we set the waterproof on the surface of structures to prevent ingress of water into the structures. For waterproofing systems, we request higher performance. But we can't set the waterproofs without any errors at all times. We must prepare the drainage systems as the backup of waterproofs to minimize the influences of water infiltration. However, there are many uncertain part with waterproof and drainage. Then we carried out the some investigation about current situation of waterproof and drainage for hybrid structures.

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 To provide the background informations for performance-based design of joining for FRP structures and FRP bonding for steel structures, the subcommittee on investigation research of joining of FRP and steel at committee on Hybrid Structures in Japan Society of Civil Engineers investigated the current researches, the design standards and the examples of joining design for FRP structures and FRP bonded steel structures for over two years. This report presents a summary of accomplishment report of "Advanced technologies of joining for FRP structures and FRP bonding for steel structures", Hybrid structure report 09 by subcommittee. This report is divided into two sections, namely the first section is "Design concept and strength evaluation of joining for FRP structures" and latter section is "Evaluation of FRP bonding for the case of repair or strengthening of steel structures".

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