Modeling of Prestressed Concrete Bridge Girders

Reinforced and prestressed concrete (RC and PC) bridge girders are crucial to the safety and serviceability of structures subjected to shear. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS). CSMM for PC was recently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). To create SCS, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, were determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale was then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally, the formulated results with RC/PC plane stress elements were implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique was validated by comparing the simulated responses of full-scale PC bridge girders subjected to vertical loads. This multiscale modeling technique greatly improves the simulation capability of RC and PC beam structures available to researchers and engineers.