The authors had proposed seismic retrofitting method by compressive CFT brace, and carried out the experimental studies of one-bay and one-story frames retrofitted by this method. In this study, the analytical models have been developed for evaluating the load-deformation relations of the tests which showed the behavior of buckling of the brace and bending behavior of whole of the retrofitted frame. Based on the good agreement between the tests and the analyses, the static and dynamic analysis of real size of RC buildings have been conducted for studying the effect on our proposed retrofitting method. From the results of the analytical studies, the authors have been able to evaluate the enhanced effect of lateral load carrying capacity and reduction effect of maximum story drifts against the three different earthquake motions of which maximum velocity is normalized as 0.5m/s.
Prestress loss of lower flange concrete due to creep and shrinkage during the storage period is regarded as one of the main design loads for long span preflexed beams. Rigorous and approximate solutions for the prestress loss are proposed and the creep coefficient and the shrinkage strain are assessed based on test results of a model specimen. The cracking load and the post cracking behavior of the specimen are accurately estimated using the assessed values in the proposed formula. Furthermore, the cracking load is predicted to decrease by about 15 percent when the storage period is increased from two weeks to two months.
High flowability and resistance to segregation are required in self-compacting concrete. Not only the flowing analysis but also the segregation analysis are necessary in the workability predictions. The segregation behavior should be indicated quantitatively in the segregation analysis. In this research, not the property of mortar itself such as yield value and plastic viscosity but the interaction property between coarse aggregate and mortar content when these materials are segregated is discussed. A ball was subjected to reversed cyclic movement in the mortar and the resistant force against the relative movement was measured in the experiments. From experimental results, it was clarified that the interaction behavior could not be expressed by Bingham model and a new rheological model was proposed to express the interaction behavior. A method to estimate the sedimentation of coarse aggregate was appeared as an example of application of this rheological model.
In this study, dynamic response analysis of a PC bridge was carried out by changing the gap size and type of rubber shock absorber. Damage of the end of bridge girder and the bridge pier bottom on the results of dynamic response analysis was evaluated by using the damage evaluation level introduced by the results of impact analysis of three-dimensional finite elements and the results of quasi-static cyclic loading experiments on actual scale RC bridge piers. As a result, it is clarified that rubber shock absorber of poly rubber fiber is effective on the pounding of bridge girder.