基于有限元模拟的后张法预应力损失评估

Evaluation of Post-Tensioned Prestress Loss Based on Finite Element Simulation

摘要: 为研究后张法预应力混凝土梁在长期服役过程中的锚头局部下陷变形及预应力损失规律，本文基于实测收缩徐变数据，采用Midas FEA与Midas Civil有限元软件建立了精细化数值模型。混凝土采用实体单元，预应力钢绞线采用桁架单元，锚具及锚垫板采用刚性面单元，并考虑嵌入式约束、面–面接触及绑定约束等连接方式。模型划分为制梁、存梁、架梁三个阶段，以及混凝土浇筑养护、预应力张拉、锚固、长期服役四个施工阶段，综合考虑锚具回缩、钢绞线松弛、收缩徐变及环境温度等时变效应。通过与6片试验梁在430 d内的实测数据进行对比分析，为后张法预应力混凝土梁的锚固体系优化、预应力损失估算及长期性能评估提供了数值与试验双重依据。

Abstract: To investigate the local subsidence deformation of anchor heads and the associated prestress loss in post-tensioned prestressed concrete beams during long-term service, this paper establishes a refined numerical model using the finite element software Midas FEA and Midas Civil, based on measured shrinkage and creep data. Concrete is modeled with solid elements, prestressing strands with truss elements, and anchorages and bearing plates with rigid surface elements, incorporating connection types such as embedded constraints, surface‑to‑surface contact, and bonded contacts. The model is divided into three stages—beam fabrication, storage, and erection—and four construction phases: concrete casting and curing, prestressing tensioning, anchoring, and long‑term service. Time‑dependent effects, including anchor set, strand relaxation, shrinkage and creep, and ambient temperature, are comprehensively considered. Through comparative analysis with measured data from six test beams over a period of 430 days, this study provides both numerical and experimental bases for the optimization of the anchorage system, estimation of prestress losses, and long‑term performance evaluation of post‑tensioned prestressed beams.