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A design methodology for a low-volume road bridge alternative: Steel beam precast units.

机译：小体积道路桥梁替代方案的设计方法：钢梁预制单元。

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摘要

Recent reports have indicated that 23.5 percent of the nation's highway bridges are structurally deficient and 17.7 percent are functionally obsolete. A significant number of these bridges are on the Iowa secondary road system where over 86 percent of the rural bridge management responsibilities are assigned to the counties. Some of the bridges can be strengthened or otherwise rehabilitated, but many more are in need of immediate replacement.; In a recent investigation, HR-365 "Evaluation of Bridge Replacement Alternatives for the County Bridge System" several types of replacement bridges that are currently being used on low volume roads were identified. It was also determined that a large number of counties (69 percent) have the ability and are interested in utilizing their own forces to design and construct short span bridges. In reviewing the results from HR-365, a "new" bridge replacement concept was developed.; This concept involves the fabrication of precast units (two steel beams connected by a concrete slab) by county work forces. Deck thickness is limited so that the units can be fabricated at one site and then transported to the bridge site where they are connected and the remaining portion of the deck placed. Since the bridge is primarily intended for use on low-volume roads, the precast units can be constructed with new or used beams.; In the experimental portion of the investigation, there were three types of static load tests: small scale connector tests, "handling strength" tests, and service and overload tests of a model bridge. Three finite element models for analyzing the bridge in various states of construction were also developed and extrapolated to various bridge configurations.; Small scale connector tests were completed to determine the best method of connecting the precast double-T (PCDT) units. "Handling strength" tests on an individual PCDT unit were performed to determine the strength and behavior of the precast unit in this configuration.; The majority of the testing was completed on the model bridge (L = 9,750 mm (32 ft), W = 6,400 mm (21 ft)) which was fabricated using the precast units developed. Some of the variables investigated in the model bridge tests were number of connectors required to connect adjacent precast units, contribution of diaphragms to load distribution, influence of position of diaphragms on bridge strength and load distribution, and effect of cast-in-place portion of deck on load distribution. In addition to the service load tests, the model bridge was also subjected to overload conditions. Using the finite element models developed, one can predict the behavior and strength of bridges similar to the laboratory model as well as design them.; Based on the experimental investigation and analytical models that were developed to describe the model bridge behavior, a design methodology for the PCDT bridge has been developed for the bridge superstructure. This design methodology has been programmed in to an easy to use program that allows quick and easy bridge design. A pre-prepared set of plans has also been developed that can be used to construct the PCDT bridge superstructure.
机译：最近的报告表明，全国23.5％的公路桥梁存在结构缺陷，而17.7％的功能已过时。这些桥梁中的很大一部分都位于爱荷华州的二级公路系统上，其中超过86％的农村桥梁管理职责分配给了县。一些桥梁可以加固或以其他方式修复，但还有更多桥梁需要立即更换。在最近的调查中，HR-365“县级桥梁系统的桥梁替代方案评估”确定了目前在小流量道路上使用的几种替代桥梁。还确定了许多县（69％）有能力并且有兴趣利用自己的力量来设计和建造短跨度桥梁。在审查HR-365的结果时，开发了“新的”桥梁更换概念。这个概念包括由县工作人员制造预制单元（由混凝土板连接的两个钢梁）。甲板的厚度受到限制，因此可以在一个位置上制造这些单元，然后将其运输到连接它们的桥架位置，并放置甲板的其余部分。由于该桥主要用于小流量道路，因此可以用新的或使用的横梁构造预制单元。在研究的实验部分中，有三种类型的静态载荷测试：小规模连接器测试，“操纵强度”测试以及模型桥的服务和过载测试。还开发了三种用于分析各种施工状态下桥梁的有限元模型，并将其外推至各种桥梁构造。完成了小型连接器测试，以确定连接预制双T（PCDT）单元的最佳方法。在单个PCDT单元上进行了“处理强度”测试，以确定该配置中预制单元的强度和性能。大多数测试是在模型桥上完成的（L = 9,750 mm（32英尺），W = 6,400 mm（21英尺）），该桥是使用开发的预制单元制造的。在模型桥梁测试中研究的一些变量包括连接相邻预制单元所需的连接器数量，膜片对载荷分布的贡献，膜片位置对桥梁强度和载荷分布的影响，以及桥梁的现浇部分的影响。甲板上的载荷分布。除了服务负载测试之外，模型桥还受到过载条件的影响。使用开发的有限元模型，可以像设计实验室模型一样预测桥梁的行为和强度，并进行设计。基于描述模型桥梁行为的实验研究和分析模型，为桥梁上部结构开发了PCDT桥梁的设计方法。该设计方法已被编程为易于使用的程序，可以快速，轻松地进行桥梁设计。还开发了一套预先准备的计划，可用于构造PCDT桥梁上部结构。

著录项

  • 作者

    Phares, Brent Matthew.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 228 p.
  • 总页数 228
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;
  • 关键词

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