Over the past few decades, premature deterioration of reinforced concrete structures exposed to severe environmental actions and mechanical loading has become a serious problem. Previous studies have shown that the use of ultra-high performance fiber reinforced concrete (UHPFRC) improves the structural response and extends the durability of concrete structures. In this study, the flexural behavior of reinforced concrete beams retrofitted with UHPFRC is investigated and experimental results are compared with 3-D finite element analysis.The experiments were performed on reinforced concrete beams repaired in tension and compression zone, with UHPFRC of varying thicknesses. The flexural strength of repaired beams was investigated by four-point bending test and compared with that of reference beam without repair. Experimental and analytical results indicate that the ultimate flexural strength of RC beams repaired with UHPFRC in tension and compression zone is increased, with the increase of UHPFRC thickness. Thereafter, a parametric study was carried out by using MSC/Marc simulation to investigate the influence of tensile properties of UHPFRC and yield strength of tension steel on the flexural capacity of repaired beams. The investigation shows that the UHPFRC improves stiffness and delay the formation of localized cracks, thus, improving the resistance and durability of repaired beams.

In cold and snowy regions, frost damage happened in an RC bridge deck slab leads to horizontally layered cracks, which results in the disintegration of cover concrete. Since this deterioration mode occurs inside an RC slab, it is usually difficult to detect them. It is possible that the slab performances have already decreased when the deteriorations appear on the exterior surface. As a preliminary step towards the establishment of a method for evaluating the structural performance of such a damaged RC slab, the purpose of this paper is to investigate the relationship between deteriorations and structural behaviors and to study the effect of an epoxy injection repair. For simplification, RC beams are prepared with artificial cracks that simulate deteriorations and these were made by the use of expansive agent. These beams are tested in flexure. Since the damage is volumetric, image analysis is useful to capture the two-dimensional deformations. It is shown that with different deterioration depths that is a part of the compression side of the beam or full of the height, there are differences about the deformation behaviors, the repair effects and the distributions of maximum and minimum principal strain.

No abstract

<p>In order to improve the maintenance and management of the highway bridge deck, a test equipment was developed for grasping the rigidity of the deteriorated deck using the deformation of the deck obtained by the impact load. A soundness evaluation system of the bridge deck using the impact test result has been constructed, and this evaluation system utilizes the curvature of the neighbourhood of the load application point. The degradation degree was evaluated from the relationship between curvature and Young’s modulus calculated using deflection. When any abnormality is observed in the periodic inspection of the highway bridge deck, load bearing performance can be evaluated at an early stage by applying this system.</p>

In a road bridge, drainage facilities are installed to discharge the water on the bridge surface. For each drainage facility, installation spacings are exemplified by waterproof manuals and others, but the quantitative sharing and drainage capacity of each facility and bridge surface have not been clarified. Also, it is thought that water will be stagnant due to bridge surface irregularities generated during construction or during service. However, no regulations on the concavities and convexities about the slab surface are clearly shown in construction standards. Therefore, in this study, surface shape measurement and water sprinkling test on unpaved actual bridge slab were carried out. From the results, we confirmed the possibility that irregularities on the slab surface affect the tendency of local water stagnation. Since only one bridge was studied in the current study, we have not confirmed the influence of gradient magnitude on the drainage capacity of uneven slab surface. It is a future task to clarify the relation between surface gradient and allowable irregularity size and to develop a standard for controlling irregularities on slab and pavement surface.