Thin UHPFRC slabs without conventional reinforcement as light-weight structural elements
Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) is a material characterised by significantly improved mechanical and durability properties compared to other concretes. In recent years, an important research effort has been made to identify appropriate structural forms and to provide practical design rules allowing efficient UHPFRC structures to be conceived. This paper presents the results of an experimental and theoretical study on the structural behaviour of thin UHPFRC slabs without conventional reinforcement. It is shown that these elements can provide high bending resistance, and, applied in an appropriate structural arrangement, lead to strong and light-weight structures that cannot be built with ordinary reinforced concrete. The favourable behaviour of thin UHPFRC members results from material mechanical properties: high compressive strength and significant ductility in tension of thin UHPFRC members lead to a ductile bending response, even when conventional reinforcement is not provided. It is demonstrated that the theory of plasticity can be safely used to assess the bending failure load for thin UHPFRC slabs. A practical expression is proposed to define the resistant plastic moment, allowing an easy estimation of the bending load-bearing capacity of thin statically indeterminate UHPFRC elements. The results are compared with experimental data on slabs of various thicknesses, showing good agreement.
Ductal Seonyu footbridge
Seoul Seonyu footbridge links the main town of Seoul to Sunyudo Island in the Han river. The footbridge consists of two steel accesses that will be borne by a Ductal® arch. The span length of the a...
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.