In this study, an evaluation method is proposed about plastic factor and hysteresis energy by only elastic analysis considering total input energy within earthquake duration and unit input energy within a unit period in the earthquake. Furthermore, damage estimation method of structures is proposed by this method applied to past a damage index.

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Almost of past studies on failure mode and seismic ductility of RC columns are for members with many hoop reinforcements, and a few studies are for members with few or no hoop reinforcements. On the other hand, many existing RC piers with rather large section have few hoop reinforcements, and seismic capacities of these structures should be made clear. In this studies static, reversal cyclic loading tests were taken by using the reduction models of RC column without hoop reinforcements. As a result, we showed that the collapse mode can be predicted by shear-to-moment capacity ratio (Vc′/Vmu), and the large ductility was obtained without hoop reinforcements in case of flexural collapse.

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The key to development of a reliable concrete production system and stabilization of batch qualities lies in accurate scaling and adjustment of the quantities of each ingredients. Changing surface moisture of sand is the most influential factor in the fluctuation of concrete quality, and many types of moisture testing apparatus have recently been developed for controlling it. However, it is difficult to precisely evaluate the level of sand surface moisture. We propose a new batching method wherein, by combining sand and water, the relative quantities of surface moisture and sand can be accurately measured. This report outlines a highly reliable production system based on this new batching method, and also addresses the effects of the new methods on the stabilities of batch quality.

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The nonlinear dynamic analysis was carried out by extending the lattice model analysis. The purpose of this study is to simply estimate the behavior of reinforced concrete piers subjected to seismic loading. The targets of the analysis are the reinforced concrete piers designed by 4 major international seismic design codes. The nonlinear static and dynamic analyses were performed. The analytical results on the maximum displacement response and maximum capacity obtained by the lattice model were compared with those by finite element analyses. As the result, the prediction according to the lattice model was confirmed to be equivalent to that by FEM. Finally, the virtual seismic wave was input, and the mechanical behavior of designed RC piers was evaluated.

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The purposes of this study are to propose an experimental method for predicting the long-term Ca leaching from concrete and the deterioration of concrete caused by Ca leaching. This method consists of a combination of electro-chemical test and diffusion test. And the estimated years of Ca leaching can be obtained by using a technique combined the results from electro-chemical and diffusion tests. Also, the concrete deterioration caused by Ca leaching can be predicted by examining the specimen after Ca leaching. The validity of this method is verified comparing the prediction results with the investigation of an existing structure used for 100 years. Finally, the influence of mix proportion upon the concrete deterioration caused by Ca leaching is investigated using this method.

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Present member safety factors for punching shear strength of RC slabs in the specification of Japan Society of Civil Engineers have been determined on the engineering experiences and it is lacking in a theoretical basis. In this study, the accuracy and dispersion of the various calculation formulas proposed before were examined. In order to calculate more appropriate failure probability, several probability distribution functions were applied to each calculation results, considering the ratio of calculation to the experimant as a variable. Calculating method of safety factor for the RC slab member was proposed.

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A local bond characteristic of the deformed bar embedded concrete is affected by experimental conditions and its position along the steel bar. In the recent paper published by Shima, the bond-slip function considered steel strain was proposed in 1987. However, there are some exceptions to Shima's function, under different conditions of loading method and concrete sectional area from Shima's experiments. Moreover, we suggested that the bond-slip relationships were affected by the condition of concrete axial stress. In this paper, we performed experimental evaluations of the effect of concrete axial stress on bond-slip relationships. As a result, it was confirmed that the bond-slip function depended on loading method and stress properties around steel bar.

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Seismic retrofitting on existing RC columns have been carried out, and the steel jacket method has been mainly adopted. But the steel jacket method can't use where spaces under viaducts are used for stores and offices. So, we developed the new seismic retrofitting method which could be easily adopted at spaces being used under viaducts. In this method with external lateral reinforcements, lateral reinforcements do not yield if there is some spacing between extemal lateral reinforcements and column surfaces, or shear-to-moment-capacity ratio (V_yd/V_mu) is over 2.3. And flexural capacity which is larger than that of normal RC columns is obtained with a lower ratio of lateral reinforcement.

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This paper introduces research and development of the method of evaluating concrete strength using ground-penetrating radar. It has been presumed that concrete strength can be estimated from the propagation velocity of radio waves and attenuation there of. Concrete strength is a very important factor for the assessment of deterioration and the residual load carrying capacity of concrete structures. Ground-penetrating radar can provide a complete inspection along each scan line, obtain quantitative and continuous data, save time, and make the investigation work safe.

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This paper has been conducted to develop a novel system for pumping concrete with a minimizing degree of the pulsation in the pipe. A pumping devise designed on a small scale has two hydraulic cylinders: one for a main stream and the other for a supplemental stream, respectively. A visualization technique was employed to determine satisfactory levels of the pulsation of the supplemental stream that resulted in minimizing the pulsatile flow of concrete flowing through the main pipe after being combined with the supplemental stream.
This research concludes that pumping concrete could be operated most smoothly and without causing an adverse pulsation through the pipe by arranging the pulsation levels of the supplemental stream with the main flow of a certain level of the pulsation when the angle of confluent is 45-dgree. Also, it was found that there existed was the segregation of model concrete in confluent during pulsatile flow and that the volumetric ratio of coarse aggregate to mortar influenced the segregation of concrete.

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The main aim of this study is to investigate the factors governing the post-peak cyclic response of laterally loaded reinforced concrete cantilever columns. A series of experiments are conducted, in which five reinforced concrete columns are subjected to cyclic lateral displacement. Much attention is paid to cover concrete spalling and the large lateral displacement of reinforcement. Specimens are designed so that the buckling of reinforcement and cover concrete spalling can be clearly observed. Finite element analyses are also performed using enhanced nonlinear fiber models, which are verified in member level by comparing with experimental results.

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The objective of this study is to investigate the possible collapse mechanisms of reinforced concrete columns. Analyses are performed to study the effect of both material and geometrical nonlinearities in the post peak response of flexural columns. Discussion is mainly focussed on the restoring force characteristics, especially in large deformation range, of RC columns having high shear capacity so that the ultimate failure is governed by bending.

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Various parameters influencing consistency of fresh concrete and mortar and are utilized for predicting workability. Those parameters are ratio of paste volume to void content of densely compacted aggregate phase, free water content, surface area, shape and water retainability of aggregates and powder materials. It was found that slump of concrete varied linearly with free water, but non-linearly with other parameters. A mathematical model for predicting flow spread of mortar and slump of concrete was formulated and verified with the actual results. It was found that the model could be used for concretes and mortars made from various types of powder material, however, without chemical admixture with satisfy accuracy.

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In this study, the frictional resistance at the deviators is incorporated in the calculation of cable strain. The equation of cable strain, which is based on the deformation compatibility of cable, is expressed in the general form for the analysis of externally prestressed concrete beams with normally external cable as well as externally prestressed concrete beams with large eccentricities. Application of the developed equation in the numerical analysis is carried out to verify its accuracy. It is found that the structural behavior of externally prestressed concrete beams can satisfactorily predict throughout the entire loading range up to failure. A good agreement with experimental data is found.

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