Analysis of Temperature Sensitivity and Cracking Causes in Suspension Bridge Anchorage Based on Numerical Simulation

Abstract

Mass concrete, a common structure in bridge engineering, is frequently threatened by cracking. Based on the gravity anchorage of a long-span suspension bridge that has been in operation for more than ten years, the causes of the cracks growing year by year in the anchorage were analyzed in this paper. The refined numerical model of the anchorage was established using the space finite-element software. Taking full account of the environmental characteristics of the bridge site, the temperature sensitivity of the anchorage was simulated and analyzed, as well as the stress distributions on the surface of each side of the anchorage at different temperatures. The calculation results showed that there is little correlation between anchorage cracking and anchorage bolt force. Under condition two, the temperature increased 20°C, the principal tensile stress of anchorage reached to 1.5 times of the allowable stress. Under condition six, the anchorage surface temperature at 40°C suddenly dropped to 20°C, and the principal tensile stress reached 2.4 times the allowable stress. Thus, under the dual effects of internal and external constraints, the cold hit effect of the mass concrete anchorage resulted in the sudden drop of the surface temperature of the anchorage concrete to produce “internal constraint cracks”, and the overall temperature rise caused the expansion of the anchorage concrete to produce “external constraint cracks.” The two types of cracks led to the vertical cracks of the anchorage. Additionally, the environmental and construction factors were the main causes of the cracking in transverse construction joints. Finally, the anchorage was reinforced with high-performance concrete with an anticrack reinforcement mesh, which presented good results in the follow-up observation, providing a certain reference value for similar projects.