Fatigue prediction life of RC slabs is carried out using S-N curve equation and punching shear capacity equation. However, the punching shear capacity has a significant effect on the number of repetitions to failure estimated from S-N curve equations. In particular, in the design criteria amended in 1980, the slab thickness was increased considerably in accordance with the design span of RC slabs, the design volume of vehicular traffic, and the difficulty of construction. As a result the punching shear capacity was increased, so the number of repetitions to failure estimated from the S-N curve also increased, and the number of years'service also increased greatly, which was not a practical result. Therefore in this research the punching shear capacity with respect to slab thickness was smoothed, taking into consideration the slab spans prescribed in the Specifications For Highway Bridges, to enable life prediction and integrity evaluation to be carried out for slab span lengths up to 4.0 m as prescribed by the specifications for highway bridges.

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In Tohoku region, many reinforced concrete (RC) decks of highway bridges are suffered severe traffic load and the repeat of traffic load in parallel with chloride attack and freeze injury leads serious damage of fatigue cracks. It is important to evaluate the deterioration rating of RC decks in quantitative and engineered method.
In this paper, the authors introduce the evaluation of deterioration rating of RC deck with falling weight deflectometer (FWD) measuring pavement distress. The measured deflections by the FWD are confirmed to be useful method to verify the deterioration rating of bridge deck.

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In the case of sidewalk widening of existing bridges, light -weight deck is desired to reduce the dead load. From the reason, the FRP deck for widening sidewalk was developed to advantage for corrosion resistance and light-weight. In this research, in order to confirm the applicability of the FRP deck to the bridge, the static strength tests of a full-scale specimen were conducted focusing on vertical load on overhang part and horizontal load on protective fence for a pedestrian and a bicycle. Furthermore, in order to investigate the static strength in the attachment of a main girder and the FRP deck, the element examination which paid its attention to the attachment was carried out. This paper reports these test results and studies the applicability to highway bridge deck.

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Ribbed arch form (RAF) is a mortar form reinforced with polypropylene fibers, and is manufactured by extrusion molding and autoclave curing. As the material of RAF is high strength and environmental durable, it's suitable for permanent forms of RC slab. RAF consists of upper projections, flat plate and lower ribs. Upper projections play a role in bonding with concrete, and lower ribs resist for concrete weight and working loads in casting. In this paper, material characteristics of RAF are described. And results of wheel trucking test of RC slab applying RAF are reported. This combined slab of RC slab with RAF endured heavy loadings corresponding to more than 100 years services in Japanese arterial highways. Furthermore, loading tests of the combined slab as a part of main girder are carried out to survey the contribution of RAF for girder action.

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Kita Bisan-Seto Bridge is a suspension bridge with stiffened truss girder, and has 990m center span. Its highway section is composed with orthotropic steel decks (OSD). There are a large number of steel plates that are fillet-welded to bottom flanges of transverse ribs of the OSD. The plates are for hanging scaffoldings in maintenance works. It was predicted that passing vehicles cause high stress in the bottom flanges, while this type of weld joint is classified in relatively low fatigue strength category. The authors performed 3-day stress measurement in order to study fatigue conditions. The fatigue life is evaluated as about 100 years, but it can be a half of the evaluation because of welding quality and accuracy of evaluation method.

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Steel structures may suffer deformation during hot dip galvanizing due to abrupt changes of temperature. A large-sized structure such as steel panels of composite slab is especially subject to extreme difference of temperature. Consequently, large thermal displacement is generated in structural members and can be left as residual deformation. Therefore, we clarify thermal displacement arising in panels of composite slab product during hot dip galvanizing process by the immersion test and the three-dimensional thermal conductivity and thermal stress analysis. Based on the above analysis, countermeasures to avoid displacement are examined when galvanizing composite slabs.

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The authors have developed a steel-concrete composite hollow-core slab. The box-like components welded on lower steel plate has functions of reducing the weight of the slab and shear connectors between steel and concrete. The slab was verified to have sufficient fatigue strength through the fatigue tests with wheel running machine. Moreover, the punching-shear strength of the slab after fatigue test coincided well with one calculated by the conventional estimate equation.

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構造工学論文集A, Vol.60A, pp.1169-1177, 2014に誤りがありましたので修正しました．

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