Flexural response of Ultra-High-Performance Concrete (UHPC) hybrid bridge deck connections made with local materials

Abstract Although using of UHPC improves the mechanical properties of concrete, it is not widespread used, due to several factors; for instance, its high material cost, special curing requirements, and lack of widely accepted design guidelines. This study aims to find an appropriate Ultra-High-Performance Concrete (UHPC) mixture, using locally available materials. In addition, the flexural response of this locally made UHPC mixture in hybrid bridge deck connections has been studied. The effect of different parameters such as percentage of silica fume, fine aggregate type, glass powder content and steel fiber volume fraction were investigated. The compressive strength results showed that a 28 days-strength of 140.3 MPa (20.35 ksi) has been achieved by using basalt as fine aggregate and 20% silica fume by weight. To investigate the applicability of this locally produced UHPC in bridge joints closure, two full scale, 8 ft. clear span, hybrid bridge deck slabs with UHPC closure were constructed and tested under monotonic loading. The load–deflection behavior of the hybrid connection confirmed that the deflection increased linearly until the initiation of cracks, after that it was increased non-linearly up to the failure of the connection. UHPC experienced less strain than high strength concrete (HSC) under compression. The hybrid connection produced with local UHPC showed moment capacity increase by more than 80% compared to NSC. The Moreover, a moment–curvature analytical model of hybrid bridge deck connection was developed to predict ductility, curvature, and stress distributions in closure connections. The model was able to predict initial stiffness and ultimate flexural moments of UHPC composite connections very well.