Evolution Law of Concrete Interface Stress of Rigid-Frame Arch under Construction and Its Impact on Ultimate Load-Bearing Capacity

Abstract

To study the evolution of stress on the ring and segment interfaces during the construction process of the concrete encapsulation of the main arch ring in a rigid-frame arch bridge, alongside its impact on the ultimate load-bearing capacity of the main arch ring, a 1:10 scale model experiment was conducted by taking the 600 m Tian’e Longtan Bridge as the prototype. The key cross-section concrete strain data were collected during the entire construction process of the main arch ring via fiber-optic strain sensors, which were used to investigate the stress evolution at ring and segment interfaces. ANSYS APDL was employed to simulate the ultimate bearing capacity under various loading conditions of two different finite element models, which were, respectively, formed segmentally and by single pouring. The results revealed that (1) after the closure of the concrete encapsulation of the main arch ring, the concrete stress in the cross-section exhibits significant stress disparities. At the same cross-section, the level of the web concrete stress can reach 76% of the floor concrete stress, while the roof concrete stress level is less than 20% of the floor concrete stress. (2) At the junction of two adjacent work planes, there are considerable differences in the stress levels of the concrete on both sides. After the closure of the main arch ring, the intersegment stress ratios of the floor, web, and roof concrete are 60~70%, 40~60%, and 0~5%, respectively. (3) Loading conditions remarkably affected the ultimate bearing capacity of the main arch ring. Under mid-span loading and 1/4 span symmetrical loading conditions, compared to single-pour concrete encapsulation, the ultimate bearing capacity of the main arch ring with concrete encapsulated by segmented and ring-divided pouring decreased by 19.16% and 5.23%, respectively, compared to single-pour concrete encapsulation. This suggests that the non-uniformity of stress distribution in the concrete sheath can lead to reductions in the ultimate bearing capacity of the arch ring.

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“…The parameters of the stress-strain state at the moment of loss of bearing capacity are given in Table 1. Source: compiled by the authors Additionally, for small values of flexibility, the bearing capacity is mainly determined from the condition of strength or rigidity, and in flexible elements from the condition of stability (Fan et al, 2023). For example, for the considered rods with a length of l 0 = 3 m, l 0 = 4 m and l 0 = 6 m at the moment of exhaustion of the bearing capacity, the reinforcing rods with numbers 3, 4 and 5 reach the yield strength, and the remaining rods work within the limits of elasticity.…”

Stress-strain state and bearing capacity of compressed reinforced concrete elements of annular section

“…Using equation ( 2) to determine the normal force and bending moment caused by compressive stresses in concrete, provided that the neutral axis is outside the section (that is, at specific parameter values), the following can be derived (3)(4)(5):…”