【作者】 郭超；

【导师】 亢景付；

【作者基本信息】 天津大学 ， 建筑与土木工程， 2012， 硕士

【摘要】 通过混凝土应变计等观测仪器来监测结构的应力状态,一直是研究复杂结构工作性态和检验计算结果正确性的重要手段,也是大型重要工程在线监测预警预报的主要方法。但基于混凝土应变计观测数据的温度应力解析方法,至今未能得到解决,使大量观测数据得不到合理分析,因而观测仪器不能发挥其应有的在线监测预警预报作用,本文的主要目的是对基于混凝土应变计实测数据的温度应力分析方法进行初步研究。本文对固端约束及弹性约束状态混凝土试件的温度应力进行了试验测定。混凝土试件为直径105mm、高度370mm圆柱体,内部中心位置埋设混凝土应变计和温度传感器,试件外侧缠绕电热带,电热带外侧用绝热性能良好的聚氨酯泡沫填缝剂密封。试验过程中,试件的升温幅度由温度传感器控制,试件的变形用内埋式混凝土应变计和外设千分表测定,温度应力用荷载传感器测定。对混凝土试件升温较传统的做法是使用水浴或油浴进行加热,在试验中自行设计了电热带加热方案及相应的保温措施,使得给混凝土试件提供较为均匀的温度荷载时,还可以方便地使用约束装置以满足相关条件的模拟。结果表明:(1)自行设计的电热带加热方案能够给混凝土试件施加较为均匀的温度荷载,升温幅度可达70℃;(2)在固端约束及弹性约束状态下,温度应力与温度变化之间具有良好的线性关系,混凝土应变计的应变变化与温度应力之间也存在良好的线性关系,但温度应力的实测值远小于理论值。(3)在约束程度较强,温度场均匀变化时,使用混凝土应变计测定温度应力可以取得较理想的效果。更多还原

【Abstract】 Through the concrete strain gauges and other observation instruments to monitor the stress state of the structure , has been an important tool to study the work state of the complex structure and verify the correctness of the calculation results , but also an primary method of the early warning and forecasting of the important project. However, the method of thermal stress analysis based on observations of the concrete gauges has not been resolved, so that a large number of observational data cannot be analyze reasonably ,and the observing instruments cannot play their due role in the online monitoring and early warning forecasting. The main purpose of this paper is to analyze the thermal stress based on the measured data of the concrete strain gauge preliminarily.The thermal stress of the concrete specimen with fixed and elastic restraints at both ends was measured by applying the temperature load on the specimen with an electric heater cable .The concrete specimen is a cylinder with 370mm in height and 105mm in diameter and fixed by the load distribution plates of the testing machine, a vibrating wire strain gauge and a temperature sensor were buried in the center of the specimen, the electric heater cable was wrapped on the lateral surface of the specimen, which was sealed with a layer of polyurethane foam with excellent heat insulating property. In the process of the experiments, the temperature rise was controlled by the temperature sensor, the thermal deformation of the specimen was measured by both embedded vibrating wire strain gauge and the dial gauges installed on the test machine, and the thermal stress was detected by the load sensor.The concrete specimens are heated in water or oil traditionally; In the test a heating cable program and an insulation system are designed, Which provide a more uniform temperature load and the easily use of restraint setup to meet the conditions of the simulation for concrete specimens.The results showed that:(1) The heating cable heating program designed can supply an uniform temperature load to the concrete specimens , a 70℃of the temperatures rise can be reached; (2) In the state of ends restraint, the thermal stress produced in the specimen is linearly dependent on the temperature rising, and the strain changes measured by the strain gauge is also linearly correlate to the thermal stress, but the measured values of the thermal stress are much smaller than theoretical ones.(3) In the state of ends restraint strongly and the temperature field changes uniformly, approximate results can be obtained by using the concrete strain gauge to measure the thermal stress.更多还原