MECHANICS PERFORMANCE ANALYSIS OF A CONTINUOUS RIGID-FRAME BRIDGE WITH DENSITY GRADIENT CONCRETE

摘要

Focusing on common existing issues of long span continuous rigid-frame bridge - excessive mid-span deflection and box girder cracks, this paper proposes a new continuous rigid-frame bridge with density gradient concrete as following: reducing the structure weight and optimizing the structural mechanical performance. The continuous rigid-frame bridge with density-gradient concrete is composed of three types of concrete materials with different density. Those concrete materials are high-strength normal concrete in pier-beam consolidation, fiber-reinforced cracking-resisted high-strength semi-lightweight concrete between mid-span and pier-beam consolidation (about 1/4L), and high-strength lightweight aggregate concrete in mid-span. Through the new continuous rigid-frame bridge model, the paper analyzes the internal forces on the ultimate limit state when the bridge is in the state of an optimum completion stage, and makes clear the stress distributions in the serviceability limit state, and then discusses the principal tensile stress in combined part between different concrete materials. All the researches show that it is reasonable and reliable for mechanics performance of continuous rigid-frame bridge with density gradient concrete. The research provides a theoretical basis for the successful application of such bridge-type.