Impact of using higher strength concrete on the design of prestressed concrete bridges

Article type: Research Article

Authors: Gergess, Antoine N. | Sen, Rajan

Affiliations: University of Balamand, El-Koura, Lebanon | University of South Florida, Tampa, FL, USA

Note: [] Corresponding author. Rajan Sen, University of South Florida, Tampa, FL, USA. E-mail: [email protected]

Abstract: AASHTO highway live loads are sometimes increased to idealize more realistic traffic conditions. Certain regions in the Middle East require increasing the AASHTO HL93 live loads by a 1.5 factor based on comparisons with the British Standards HA + HB live loads. Even in the US, the AASHTO live loads may not always represent modern state-legislated truck configurations. This paper shows the impact of using higher strength concrete on the design of precast, prestressed girders subjected to stringent loading and environmental conditions. A parametric study that relates the girder size and spacing to the span length for HL93 and 1.5 × HL93 live loads as a function of the concrete 28-day strength and environmental classifications is conducted for this purpose. It is shown that increasing the 28-day concrete strength from 40 (5800) to 50 MPa (7200 psi) allow increasing the HL93 live load by 50% and reducing the service load tension stress limit from 0.5$\surd{\rm f}^{\prime}$c, MPa (6$\surd{\rm f}^{\prime}$c, psi) to zero without drastically changing the precast girder size and configuration.

Keywords: High strength concrete, AASHTO HL93 live load, standard AASHTO girders, parametric study

DOI: 10.3233/BRS-140075

Journal: Bridge Structures, vol. 10, no. 2-3, pp. 77-85, 2014