This research aims the clarification of the shear mechanism of reinforced concrete beams by means of experimental works with the image processing and analytical methods. With a combination of Modified compression field theory and Fiber model nonlinear analysis program for reinforced concrete beams, experimental results are examined. Focusing on the interaction of a bending moment and shearing force, influence of bending moment is especially taken into consideration to MCFT as the equivalent axial force calculated from fiber strains. Extraction of flexural components and shear components are by means of measurement of the noncontact displacement and image processing. As a result, the displacement by the direct measurements and that by the image processing agree with each other up to ultimate load.

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In general, the safety for earthquake is defined as the performance to prevent from collapsing of structures. However, accurate verification of collapse of structures requires adequate comprehension of seismic behavior in large deformation response, and precise evaluation of limit value of collapse. In this study, we conducted shaking table test using earthquake wave of main quake and after quake and examined the dynamic behavior of RC columns. As a result, it is evident that even if seismic response of structures reaches to the limit value of collapse in the current design standard, structures are not always collapsible, and even if structures are prevented from collapsing in a major seismicity, they may collapse after the quake depending on seismic characteristics. Therefore, we proposed a new verification method using the amplitude of response displacement for the safety performance.

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Nondestructive test for pavement structures such as FWD (falling weight deflectometers) applies a dynamic force at pavement surface and measure its wave propagation. The objective of this paper is to derive a theoretical solution of the wave propagation phenomenon. Pavement structure is modeled by multilayered systems with their material characteristics of Voigt model. Considering impulsive force/harmonic force which acts on pavement surface, wave propagation equations expressed in a cylindrical coordinate is formulated as an axisymmetric problem. Rewriting the equations by two potential functions and applying Fourier and Hankel transforms, two second order differential equations of harmonic potential functions with complex coefficients. The differential equations can be analytical solved. The solution of a system of wave equations is derived by applying inverse Fourier and Hankel transforms with boundary conditions. In order to verify the theoretical solutions, the responses from the solutions are compared with the results of ADINA, good agreement of both responses are confirmed.

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In order to establish an optimum surface protection system for newly constructed concrete structures with silane type water barrier penetrants, fundamental experimental study was conducted for 2 water barrier penetrants which have shown good waterproofing performances in 5 years exposure test.
For 3 kinds of concrete mix proportions, such as W/C of 42%, 50%, 65%, the effects of age of concrete at the application of penetrants, and the effects of water supplying conditions before and after the application, on penetration depth and waterproofing performance were examined.
The age of concrete at the application of penetrants considerably affected penetration depth and waterproofing performace. If we make a point of waterproofing performance, water barrier penetrants should be applied in early age.
The water supplying conditions before and after the application considerably affected penetration depth and waterproofing performance. The effects were different according to W/C of concrete.
Based on experimental results, a direction of surface protection system with silane type penetrants was discussed.

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For the verification of steel corrosion in upper deck of wharf type structure, a critical chloride concentration for initiation of steel corrosion (C_lim), a chloride ion concentration at the concrete surface (C₀) and an apparent diffusion coefficient (D_ap) were investigated based on site survey and long term exposure tests. For C_lim, 2.0 kg/m³ is proposed in port reinforced concrete structures, based on long term exposure test in the pool which tidal and submerged conditions were simulated. For C₀, it is proposed that C₀ is varied linearly with the distance between H.W.L. and concrete surface. For D_ap, it is proposed that characteristic value of diffusion coefficient is obtained by multiplying the estimation equation of ‘JSCE standard specification for concrete structures’ by 0.65 in case of normal portland cement.

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There is a possibility that thermal cracks occurr in an asphalt mixture due to thermal stress at very low temperature. It is difficult to evaluate the thermal stress of asphalt mixture because its physical properties considerably change on temperature, material used and mix proportion. The establishment of evaluation approach considering a dependence on temperature of asphalt mixture become issue to consider it. In this study, a testing method and analytical method to evaluate the thermal stress at low temperature is proposed, and the applicability of its analysis using viscoelastic model is discussed. This analysis uses the input data obtained from experiment on physical properties varying temperature and loading condition. The strain histories of asphalt mixture can be re-created through this proposed analysis, and it is showed that this method to evaluate the possibility of cracking at low temperature in the field is applicable.

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The thickness of the excess paste film calculated according to the excess paste theory is not affected by water cement ratio of paste. Therefore, the shift of the sand percentage that invites the largest slump of fresh concrete caused by the alteration of water cement ratio can not be explained by the theory. In this study, a new index that takes into account the adhered paste film around aggregate particles is proposed. It is clarified that the shift is caused by the adhered paste film. Furthermore, the sand percentage for the largest slump at water cement ratio of 0.65 is found to be equal to the sand percentage for the largest solid volume percentage of fine and coarse aggregate mixture. As a result, an equation for the estimation of the sand percentage when the largest slump is observed at any water cement is derived.

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Experimental tests were performed to investigate the breaking mechanism of reinforcing bars due to ASR. To investigate the effect of Alkali Silica Reaction (ASR) on reinforcing bars, a material test and a specimen test were conducted. In the material test, reinforcing bars were bent and their crack depth was measured to find the effect of bending type and rib shape. In the specimen test, 1/8 scale specimens modeling an actual bridge beam were constructed using expansion concrete to simulate ASR. Parameters were the bar type, expansion amount of concrete, environmental conditions, etc. The results showed that the depth of initial cracks was largely influenced by the bending radius and rib shape of bars. When the initial crack depth was more than 1.5% of the bar radius, the crack depth remarkably increased when applied to expansion concrete.

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