Modelagem numérica de uma ponte rodoferroviária mista de aço e concreto com laje protendida

Abstract

This study presents the numerical analysis of a road-rail bridge over the Tocantins River, with a total length of 2,344 m. The superstructure consists of composite beams with prestressed concrete at the internal supports, divided into five continuous segments. Each typical segment comprises ten spans of 55 m, except for the central segment, which includes two spans of 44 m and one span of 77 m with an upper arch. The segments can be considered independently due to the presence of expansion joints between them. The simultaneous use of composite steel-concrete structural systems with prestressed concrete is relatively uncommon. In this case, the prestressing at the supports is intended, among other purposes, to reduce concrete cracking and, consequently, to prevent water infiltration into the composite box section. It should be noted that prestress losses over time may compromise the watertightness of this structural element and potentially accelerate deterioration processes. Considering the distinctive characteristics of this structural system, its behavior remains insufficiently addressed in the literature, while simplified analytical models are often inadequate. In this work, a numerical methodology for the analysis of this bridge is presented, employing the Finite Element Method through the software ANSYS Mechanical APDL. One of the bridge segments was modeled for the simulation. A part corresponding to one and a half spans in the support region was modeled with shell element, while the remaining spans were represented by equivalent beam elements, to reduce computational cost. Compatibility between these parts was ensured through rigid elements. Strain gauge measurements were compared with the numerical response, indicating that the proposed model accurately reproduces the structural behavior. Thus, the service limit state verifications were performed, indicating that, under the adopted assumptions, the structure does not exhibit cracking that would compromise its structural capacity or service performance.