Long-term creep behavior of expansive agent core concrete in full-scale concrete-filled steel tube from the world’s largest span arch bridge study  

作　　者：Zheng CHEN Changjie WU Ben CHEN Yang YANG Weiying LIANG Yunchao TANG Jielian ZHENG 

机构地区：[1]School of Civil Engineering and Architecture,State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,Guangxi University,Nanning 530004,China [2]Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education,Guangxi University,Nanning 530004,China [3]Guangxi Polytechnic of Construction,Nanning 530007,China [4]Guangdong Provincial Key Laboratory of Intelligent Disaster Prevention and Emergency Technologies for Urban Lifeline Engineering,Dongguan University of Technology,Dongguan 523808,China

出　　处：《Frontiers of Structural and Civil Engineering》2025年第3期319-340,共22页结构与土木工程前沿(英文版)

基　　金：supported by various institutions,including the National Key Research and Development Program of China(No.2021YFB2600903);the National Natural Science Foundation of China(Grants Nos.U2006224 and 52368028);the Guangxi Natural Science Foundation,China(No.2022GXNSFFA035035);the Guangxi Key Research and Development Program(No.GKAB22036007);the Guangxi Science and Technology Major Project(No.GKAA23073017);the Middle-aged and Young Teachers’Basic Ability Promotion Project of Guangxi(No.2022KY1159).

摘　　要：The Tian’e Longtan Bridge,currently under construction and boasting the world’s largest span arch at 600 m,employs a concrete-filled steel tube(CFST)as its primary structural component,forming the stiffness skeleton upon which an outer reinforced concrete arch ring is constructed.As the internal defects of CFST,once encased by outer concrete,cannot be remedied,it becomes imperative to prevent long-term debonding of the core concrete.In recent years,expansion agents have been extensively utilized in CFST arch bridge engineering to compensate for early autogenous and thermal shrinkage.However,a comprehensive comprehension of the creep behavior of core concrete expansion under extended steel tube confinement remains elusive.To address this concern,the radial expansion process of the core concrete can be segmented into two stages:debonding and restriction.We derive a long-term deformation model for the radial expansion of core concrete during the restriction stage,based on elastic mechanics and linear creep mechanics.We represent the expansion process of these two stages uniformly using piecewise functions.Subsequently,in conjunction with the ongoing construction of the Tian’e Longtan Bridge,we measure the core concrete’s behavior in full-size CFST specimens(Φ0.92 m×12 m×0.01 m)both with and without expansion agents for up to 114 d.This validates the practicality of the creep model and enables us to determine its relevant parameters.Our results reveal that a debonding gap of 0.142 m occurred before the initial setting of the core concrete.The core concrete underwent a radial expansion of 290.1×10^(−6),with 158.3×10^(−6)being used to address early debonding,and the remaining 131.8×10^(−6)generating self-stress on the steel tube.The creep model indicates that radial creep of the core concrete persisted for approximately six months under the hoop limitation of the steel tube,resulting in a residual expansion deformation of 26.4×10^(−6)and a residual self-stress of 0.119 MPa.Additionally,axial defo

关 键 词：CFST autogenous shrinkage RESTRICTION expansion agent principle of creep superposition 

分 类 号：TU528[建筑科学—建筑技术科学]