工程科学与技术2025，Vol.57Issue(6)：142-151,10.DOI:10.12454/j.jsuese.202300987
服役劣化后RC空心板桥抗弯承载性能评估
Flexural Bearing Performance Evaluation of Deteriorated RC Voided Slab Bridges
摘要
Abstract
Objective Accurate assessment of the flexural bearing capacity of reinforced concrete(RC)voided slab bridges after service degradation is a critical aspect of bridge operation and maintenance management.It provides a reference for evaluating service conditions and making mainte-nance decisions for similar in-service bridges.This study focuses on a simply supported RC voided slab bridge with 27 years of service history lo-cated in the Shangqiao Interchange section of the Chengdu‒Chongqing Expressway.Based on inspection data,in-situ static load tests,bending failure tests in the laboratory,numerical simulations,and theoretical analysis,the research systematically investigates the flexural bearing capac-ity of the bridge structure and evaluates its operational safety based on current and outdated design codes. Methods Firstly,the historical inspection reports of the bridge structure were reviewed,with the inspection results obtained in 2020 serving as the baseline for a comprehensive analysis of the bridge's disease characteristics and distribution.Secondly,prior to the bridge's demolition,in-situ static load tests were conducted using two tri-axle heavy-duty trucks,applying four loading conditions and eight-stage loading methods to measure and analyze the strain and deflection of each RC voided slab.Based on the measured deflection data,a calculation method for the mea-sured load transverse distribution coefficient of RC voided slab bridges was proposed and compared to theoretical results.The working perfor-mance of the hinge joints between the RC voided slabs was then evaluated.Thirdly,three voided slabs were dismantled from the original bridge for bending failure tests in the laboratory,enabling experimental investigations on the flexural bearing capacity of individual slabs and revealing the failure process and mechanism of RC hollow slabs.Fourthly,a three-dimensional nonlinear solid model of the RC hollow slab was developed in ABAQUS,numerically reproducing the mechanical behavior throughout the failure process,which demonstrated high consistency with the ex-perimental results.Finally,by considering different working states of the hinge joints,the flexural bearing capacity of the original bridge was comprehensively evaluated through theoretical calculations,and a comparative analysis of its service performance and structural safety was per-formed based on both current and historical bridge design codes in China. Results and Discussions After 27 years of service,due to prolonged full-load operation,transverse cracks,longitudinal cracks,mesh cracks,hon-eycombing,bursting,spalling,and other defects were observed almost at the bottom of each RC voided slab,with hinge joint deterioration identi-fied as the most critical factor compromising the bridge's flexural bearing capacity.The damaged hinge joints impeded effective load distribution across the transverse direction and,in severe cases,even caused single-slab load-bearing phenomena,significantly undermining the bridge's structural integrity.In-situ tests revealed highly uneven mid-span deflection distributions among slabs,confirming weakened hinge joint connec-tions,which aligned with the observed hinge joint deterioration.Under the four loading conditions,the measured load distribution coefficients across the RC voided slabs were generally similar.Under eccentric vehicle loading,the maximum distribution coefficient on the loaded side reached 0.440 7,while the minimum on the unloaded side was only 0.036 3,an 11.1‒fold difference,far exceeding the theoretical 1.9‒fold ratio.This finding demonstrated that after 27 years of service degradation,the original bridge's hinge joints no longer functioned effectively as trans-verse connectors,severely impairing the overall flexural performance of the bridge structure.Bending failure tests in the laboratory showed that despite initial defects,the flexural capacity of RC voided slabs remained satisfactory.The loading behavior and failure processes of the three tested slabs were nearly identical,exhibiting typical under-reinforced beam bending failures,with residual mid-span displacements exceeding 200 mm after loading termination,yet without slab fracture.The load-mid-span deflection curves of all three slabs displayed distinct yield and failure thresholds,ap-proximating three linear segments with varying slopes.The post-yield plateau segment exhibited stable and gradual deformation,indicating good duc-tility.The average yield and ultimate loads were 544.8 kN and 605.4 kN,respectively,with a mean ultimate deflection of 271.4 mm and a ductility co-efficient of 8.51.Numerical simulations incorporating a plastic damage constitutive model successfully replicated crack propagation and slab failure processes,with simulated load-deflection curves closely matching the experimental data.Although the yield load simulation error was minimal(-2.3%),the yield deflection prediction exhibited larger discrepancies.The simulations more accurately captured the simultaneous yielding of ten-sile reinforcement and slab concrete.Therefore,numerical modeling is a valuable complementary tool to experimental studies,providing addi-tional perspectives for assessing the in-service capacity of RC voided slab bridges.Theoretical calculations indicated a mere-0.3%error between the computed and measured flexural capacities.Comparative analyses of the original bridge's flexural performance under current and historical design codes(referred to as"old code")were conducted by considering three hinge joint conditions:theoretical maximum distribution coeffi-cient,measured maximum coefficient,and extreme single-slab loading.Results showed that the bending moment effects calculated under the old code were significantly lower than those under the new code,reaching only 68.2%,65.8%,and 64.8%of the new code's values,respectively.Even under the extreme single-slab condition,the old code's requirements were met with a 60.3%reserve capacity.In contrast,the current code yielded reserves of only 49.5%,17.0%,and 3.8%for the three conditions.When based on the yield moment,the reserve capacity under the mea-sured shear key condition was merely 5.3%.Further deterioration leading to single-slab loading will reduce the flexural capacity below the mo-ment effect,pushing the slab into plastic deformation and posing severe safety risks under overload scenarios. Conclusions This study systematically analyzes post-service degradation characteristics employing multiple research methodologies on actual RC hollow slab bridges.The research provides reliable methodologies for assessing the service conditions of numerous in-service RC hollow slab bridges and offers essential decision-making references for the maintenance operations of similar structures.关键词
RC空心板桥/铰缝病害/荷载试验/荷载横向分布/弯曲试验/承载能力Key words
RC voided slab bridge/hinge joint disease/load tests/transverse distribution of load/bending tests/bearing capacity分类
交通运输引用本文复制引用
徐略勤,甘超,李修君,王佩,周建庭..服役劣化后RC空心板桥抗弯承载性能评估[J].工程科学与技术,2025,57(6):142-151,10.基金项目
国家自然科学基金项目(51978113 （）
52378482) （）
重庆英才计划项目(cstc2022ycjh‒bgzxm0133) （cstc2022ycjh‒bgzxm0133）
重庆市研究生科研创新项目(CYS23473) （CYS23473）
