The deterioration of concrete structure occurs due to various factors and additional environmental hazards. In this paper, sulfate attacks of concrete structure that caused sulfate ion in the ground were discussed. Firstly, an example of collapse due to deterioration of concrete housing foundations on land developed with coal waste in an old coal-mining area was discussed. Next, a verification test was implemented for investigations on the process of sulfate ion concentration in the test ground and concrete test pieces. As a result, it became clear that deterioration of the concrete structure was caused by an increase of the sulfate ion due to ground capillary phenomenon of soil water.

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Experimental and analytical studies were conducted so as to investigate the influence of reinforcing bar corrosion on shear bahavior of RC beams. Parameters considered were shear span ratio, corroded bars (main bar, stirrup), corrosion level and so forth. The following results are obtained: if the anchorage is sound and the maximum corrosion ratio is no more than 35%, the corrosion of stirrup has little effect on load-carrying mechanism. The transition of load-carrying mechanism, which was caused by the deterioration of bond strength due to main bar corrosion, was influenced by the variation of shear span ratio. Based on the experimental and analytical results, a calculation equation, which gave a good assessment of the experimental results, was proposed.

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A generalized design equation proposed by authors for evaluating the effects of early age shrinkage coupled with size on diagonal cracking strength of reinfoeced HSC beams is re-formulated and re-verified by adding 18 data, which showed good agreement with experimental results. A concept of equivalent tension reinforcement ratio incorporated into the present equation showed successfully the linear relationship between diagonal cracking strength and the effective depth to −2/5 power independent of the magnitude of shrinkage. On the other hand, a crack along compresson reinforcement in flexure-shear span resulted from shrinkage indicated the possibility leading to the decrease of diagonal cracking strength.

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A walking sapace in downtown Sapporo has been rebuilt in terms of appearance on the basis of a old urban planning. Although various materials and designs were used for sidewalk pavement, complaints on slip from citizens and difficulties for maintenance are mounting.
In this study, characteristics of sidewalk skid resistance were revealed through the measurement of skid resistance using SDFT and the minimum skid resistance was obtained from the slip sense test by pedestrians. The distribution of skid resitance in downtown was evaluated using these results, and it was shown that sidewalks with low skid resistance concentrated on important axes of present urban plannings.

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In the impact-echo method, the presence and the locations of defects in concrete are estimated by identifying peak frequencies in the frequency spectra. In practical applications, however, spectra obtained include so many peak frequencies that it is very difficult to identify particular defects. In this concern, SIBIE (Stack Imaging of spectral amplitudes Based on Impact Echo) is developed as an imaging technique applied to the impact-echo. In this study, the SIBIE procedure is applied to identify ungrouted post-tensioning ducts in prestressed concrete.
An applicability of the procedure to identify ungrouted tendon ducts in post-tensioned concrete girders was examined in the both cases of polyethylene and steel (tin-galvanized) sheaths. Results show a great promise for inspecting imperfectly-grouted ducts in prestressed concrete bridges.

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The authors intend to utilize precast segment method for construction of cut and cover tunnels. The previous studies including the authors' on the load carrying behavior of members with post-tensioning joints indicate that they show superior restoring force characteristics while less energy dissipation compared with those of uniform reinforced concrete members. It is also indicated that bond characteristics of prestressing steels have large influence on the load-deformation relationship of the members with post-tensioning joints. Therefore, it is important to consider the changes in bond characteristics of prestressing steels when calculating the limit values used in the seismic performance verification.
In this study, analytical investigations considering the bond characteristics of prestressing steels are done on the test results of the authors previous report. A loading test on the whole structure using a 1/3 scale model is also done and the validity of the proposed analytical method is verified.

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Acoustic emission (AE) behavior of concrete generated under compression is analyzed, applying the rate process theory. Based on Loland's model in damage mechanics, a relation between AE rate and the damage parameter is correlated. A production method for recycled aggregate is under development, applying the pulsed-power technique. In the present paper, quality of recycled-aggregate concrete is evaluated by the damage parameter, based on AE rate process analysis. Results demonstrate that the degradation ratio of recycled aggregate compared to raw aggregate could be quantitatively evaluated by the proposed method, without knowing quality of raw aggregate.

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Pavement primary responses (i.e. stresses, strains and displacements) due to horizontal loading have normally been determined by methods based on static analysis. However, when brakes are applied on the wheels of a moving vehicle or airplane, it is more realistic to consider the resulting horizontal load as dynamic and not static. In this paper, mechanistic properties of pavement layers are represented by Voigt model while displacements are explained in terms of three potentials. After that, closed form solutions are derived by using Hankel transform together with Fourier Transform. Comparing the results with the ones obtained from ADINA, a commercial Finite Element Method (FEM) package, confirms the validity of the derived solutions. Propagation of pavement responses in the vertical and horizontal directions due to dynamic horizontal loading is presented. The effect of coefficient of friction on pavement responses is also investigated by evaluating the results due to dynamic vertical and moment loading and presented in this paper.

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  The purpose of this study is to investigate the fatigue characteristic of the concrete damaged by Alkali Silica Reaction (ASR). There are three deterioration levels taken up in this study, the expansion rate 0% (a standard), 0.1% and 0.3%. After water curing for 28 days, the test pieces for the expansion rate 0.1% and 0.3% were cured in accelerating environment of 40°C and 100%R.H. While the test pieces for the expansion rate 0% were cured in water until the age of 28 days or 91 days. The uniaxial compressive fatigue tests were performed for each test piece. The upper limit stress was set at several phases between 50% and 80% of static strength. This paper clarified the relationship between upper limit stress ratio and fatigue life (S-N curve) and the change of the gradient of the S-N curve according to the progress of deterioration level. From the test results, the equations for fatigue life under compressive load were proposed based on the deterioration levels of ASR.

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  A series of cyclic loading tests was conducted using scale-modeled RC rigid frame piers which have steel brace and shear-panel-type damper members. High transverse rigidity and energy dissipation capability, which provide superior running safety for railway vehicles subjected to earthquake motions, were obtained. The seismic performance of the structure was evaluated based on experimental results and using a framed structure analysis.

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  The expanded polystyrene aggregate, whose volume was reduced by extreme infrared rays, has been expected to be used as fine aggregate for super lightweight concrete. Authors had so far obtained the basic physical properties, such as strength, segregation and fatigue and so on. In this study, the heat insulation characteristic of the EPS mortar was estimated as another added value other than the lightening. Influence of mix proportions and the thickness of EPS mortar exerted on the heat insulation effect was evaluated from the relation with solar radiation. The heat resistance was also considered experimentally.

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