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Thermal stress in concrete slabs under different constraints.

机译：不同约束条件下混凝土板的热应力。

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摘要

Previous research has shown that thermal stresses developed in concrete pavements due to daily and seasonal temperature variations may be larger than those induced due to traffic loading. Dowel bars that are used for load transfer at the transverse joints of concrete pavements introduce high stresses at their interfaces with concrete leading to various forms of transverse joint distress. To solve this problem, Shoukry et al. (2001) developed an alternative design of dowel bars called "Shok Bar" that was installed by Shoukry and his team in a concrete pavement section placed at the parking lot of WVDOT Maintenance Shop at Goshen Road, WV. The built section was instrumented to experimentally measure the strains developed in concrete slabs.; In the present work, the measured behavior of slabs fitted with Shok bars is studied and compared with that measured for slabs fitted with regular dowel bars. The effect of slab-base friction on the expansion and contraction of concrete slabs is studied. The thermal stresses known to cause the top-down transverse cracking at the mid-slab were investigated. The results indicate that the new dowel bar design reduces the concrete slab strains especially during the initial stages of concrete setting. The Shok bars reduce permanent residual strain in the slab, lower the axial forces in the dowels considerably and help in relieving curling stresses in the pavement. The measured data show that slabs fitted with Shok bars have symmetrical joint opening compared with those slabs that were fitted with regular dowel bars.; In this study the thermal diffusivity theory was used to develop a method to calculate the temperature and the thermally induced strain at different depths through the slab thickness given the time history of weather parameters: air temperature, solar radiation, relative humidity, and wind velocity. While previous research efforts were limited to sunny and clear days, this method is capable of calculating the slab temperature for a 24 hour period and also for a sequence of days including days with light rain and cloud cover. The effects of snow cover on the slab and heavy rainfall on the method have been discussed. Equations for the strains developed at the slab top and bottom were presented. The temperatures calculated by the method were compared with the values measured from the test slabs. The results from the proposed model were found to be in reasonable agreement with the experimentally measured data from the slabs.
机译：先前的研究表明，混凝土路面由于每日和季节性温度变化而产生的热应力可能要大于交通负荷引起的热应力。用于在混凝土人行道的横向接缝处传递载荷的销钉在其与混凝土的界面处引入高应力，从而导致各种形式的横向缝隙遇险。为了解决这个问题，Shoukry等人。 （2001）开发了一种名为“ Shok Bar”的销钉木杆的替代设计，由Shoukry和他的团队安装在位于WVD Goshen路WVDOT维修店停车场的混凝土人行道上。建成的部分被用来测量混凝土板上产生的应变。在目前的工作中，研究了装有肖克棒的平板的测量性能，并将其与装有常规销钉的平板的测量性能进行了比较。研究了板基摩擦对混凝土板膨胀和收缩的影响。研究了已知导致中板自上而下横向裂纹的热应力。结果表明，新的销钉设计降低了混凝土板的应变，特别是在混凝土凝结初期。推杆可减少板中的永久残余应变，显着降低销钉中的轴向力，并有助于减轻人行道中的卷曲应力。实测数据表明，与装有普通销钉的平板相比，装有Shok棒的平板具有对称的接头开口。在这项研究中，热扩散率理论被用于开发一种方法，该方法在给定天气参数（空气温度，太阳辐射，相对湿度和风速）的时间历史的情况下，通过板厚度计算不同深度处的温度和热致应变。尽管以前的研究工作仅限于晴天和晴天，但该方法能够计算24小时内的板坯温度，也可以计算连续几天的温度，包括小雨和云层。讨论了积雪对平板的影响以及暴雨对方法的影响。给出了在平板顶部和底部产生的应变方程。将通过该方法计算出的温度与从测试板测得的值进行比较。所提出模型的结果与板坯的实验测量数据基本吻合。

著录项

  • 作者

    Rao Hejamadi, Dhananjay.;

  • 作者单位

    West Virginia University.;

  • 授予单位 West Virginia University.;
  • 学科 Engineering Mechanical.
  • 学位 M.S.
  • 年度 2006
  • 页码 135 p.
  • 总页数 135
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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