Welded headed studs are used to connect steel girders and concrete slabs in steel composite bridges. However, environmental problems related to welded shear connectors have been reported, including noise and dust generation during the replacement and demolition of damaged or worn concrete slabs. To overcome these issues, demountable shear connectors that enable easy replacement of damaged or worn concrete slabs must be developed. However, conventional bolted shear connectors mainly use embedded nuts, which cannot be used in structures such as bridges because initial slip occurs and the stiffness and shear resistance strength are relatively low. To address these issues, this paper proposes a bolted shear connector that integrates the embedded nut part into the stud bolt and has a tapered shape at the bottom of the expansion column. For performance verification in regard to static shear strength and slip displacement, push-out tests were performed according to Eurocode-4, and the performance of the proposed stud bolt was compared to those of conventional welded headed studs and embedded nut-style bolted shear connectors. In addition, an analytical review was performed using the ABAQUS program for the 1/4 axisymmetric model of the push-out test. As a result of applying the material nonlinear model and the surface contact analysis, the load-slip displacement of each analysis model showed a tendency extremely similar to the experimental results. The proposed demountable bolted shear connector exhibited excellent shear performance and can be used as a satisfactory replacement for conventional welded studs because it meets slip displacement and ductility standards.

Deteriorated facility maintenance is a critical social issue in advanced countries. Its cost increases when considering the social consequences in terms of asset value and direct maintenance costs. Data from Korea’s Ministry of Land, Infrastructure, and Transport shows that there were 3454 bridges aged 30 years or over in Korea in 2017; this number will increase to 10,961 by 2027. In thirty years, maintenance costs will be incurred for more than 32,000 old bridges in Korea. These trends are also observed in the US, Japan, and Korea. Diverse studies have been conducted to predict the residual life of old bridges via bridge performance evaluation and load-carrying capacity assessments. However, criteria for evaluating bridge performance and verifying the effect of bridge maintenance are yet to be established due to two reasons. First, most studies on performance evaluation, maintenance, and rehabilitation techniques have been performed on limited specimens from building elements or through small-scale simulations that do not reflect the deterioration factors of complex materials in diverse environments. Second, the performance evaluation of bridges is difficult compared to quantitative state evaluations. As a method of predicting the future performance of aged concrete bridges, it is effective to understand the actual aged bridges through experiments, and this study intends to propose the method.

The increased volume of heavy vehicles and use of de-icing agents on concrete bridge decks accelerates the deterioration of these structures. Therefore, the rapid replacement of these structures has attracted considerable attention, with prefabricated bridges being the preferred option. Conventionally, horizontal shear connections between girders and precast decks have incorporated rebar stirrup shear connectors. Although effective for initial construction, this method renders dismantling of aged decks complex, because rebar connectors are fully embedded within girders. This study introduced an embedded separable shear connector that minimizes deck-breaking and facilitates easy reinstallation by the simple separation of the deck from the girder. Horizontal shear and flexural tests on composite girders and comparisons with various design codes were conducted to evaluate this connector. The results of horizontal shear tests confirmed that securing sufficient embedment depth is necessary to prevent the pull-out failure of shear connectors. Additionally, prestressed concrete composite girder flexural tests with improved design verified that the detachable shear connectors exhibited an approximately 60% improvement in flexural performance compared with conventional reinforcement shear connectors.

The increased volume of heavy vehicles and the use of de-icing agents on concrete bridge decks have accelerated their deterioration. Concurrently, the demand for rapid replacement of these structures and research interest in prefabricated bridges have increased. Traditionally, horizon-tal shear connections between girders and precast decks have utilized rebar stirrup shear con-nectors. Although effective for initial construction, this method complicates the dismantling of aged decks because the rebar connectors are fully embedded within the girders. The removal of concrete decks requires cutting, whereas composite decks atop girders must be demolished us-ing breakers. This process generates dust, noise, and vibrations, raising environmental concerns and causing delays in urban demolition projects due to public complaints. This study introduces an embedded separable shear connector that minimizes deck breaking and facilitates easy rein-stallation by allowing simpler separation of the deck from the girder. Horizontal shear and flexural tests on composite girders and comparisons with various design codes were conducted to evaluate this innovative connector. The results show that the proposed connector provides superior horizontal shear strength relative to traditional methods and satisfies modern ductility design criteria. Simulations confirmed that the decks could be easily separated and reassembled, maintaining shear strength under initial construction conditions.