Abstract
The use of precast segmental box girders in the bridge construction projects yields many benefits: economy, high quality, rapid construction, and minimal disruption to site. Previously, precast segments are connected together by epoxy joints. Epoxy fills in the gaps and makes strong connection, but it takes time and effort in the construction process. Later, dry joints have been introduced in the process, and hence the construction could be done much faster. However, there exists some drawback in using the dry joints. The contact surface between segments, especially at shear keys, can hardly be made smooth and well-fitted together. Consequently, the transferred shear strength cannot be developed to its full capacity. This study is an attempt to improve the capacity of shear strength of dry joints by adding steel fiber and glass fiber into concrete mixture. Considering specimens with single shear key, experiments have been conducted for shear capacities of 5 specimen types: ordinary concrete, concrete mixed with 1% and 2% steel fiber, and concrete mixed with 1% and 2% glass fiber. Results from experiments have shown that steel fiber helps increase the shear capacity of dry joints while glass fiber somehow degenerates the shear capacity and the compressive strength of concrete.
Highlights
Precast segmental bridges received much attention due to the method of construction that members can be precast in a factory, transported to the site for erection
Relationships between applied load and relative displacement in the direction parallel to the applied load are shown for 5 types of specimens: ordinary concrete, concrete mixed with 1% and 2% steel fiber, and concrete mixed with 1% and 2% glass fiber
Considering only single-keyed dry joints, specimens are made with 5 different mixtures: ordinary concrete, concrete mixed with 1% and 2% steel fiber, and concrete mixed with 1% and 2% glass fiber
Summary
Precast segmental bridges received much attention due to the method of construction that members can be precast in a factory, transported to the site for erection (see Figure 1). Rombach and Specker proposed the formula for the shear capacity of keyed dry joints, based on numerical study [3]. Shear keys are typically unreinforced, and unreinforced concrete is poor in tension. When mixing fibers such as steel or glass fibers into concrete constituent, tensile strength of concrete as well as shear capacity of monolithic beams can be enhanced [5,6,7,8,9,10]. This paper presents an attempt to improve the shear capacity of dry joints by adding steel fiber and glass fiber into concrete mixture. Specimens of single-keyed dry joints have been cast with 5 different concrete mixtures and tested for shear strength.
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