Abstract

Of the 604,485 bridges in the United States, approximately 21% are culverts having a span of 6 m (20 ft) or greater. The load rating of typical bridges presents numerous challenges. Developing load ratings for non-typical structures, such as buried arch-shaped culverts is more complex because of the culverts’ unique geometric configuration and their interaction with soil media. This paper proposes an alternative analytical method for load rating in-service reinforced concrete (RC) arch culverts that overcomes the limitations of the widely used elastic frame concept while being straightforward to implement. The proposed analytical method uses two-dimensional finite element models of the arch structure and surrounding soil media. The finite element model was first validated against experimental tests on a full-scale RC arch culvert, subjected to simulated live loads. The validated FE model was used in load rating analysis of 21 RC arch culverts with large fills. It was found that for arch culverts with fills exceeding 2.43 m (8 ft.), the controlling actions are bending moments at the crown and haunch. For culverts with fills greater than 3.05 m (10 ft.), live load effects become negligible. A revised rating formula is proposed for culverts with this characteristic.

摘要

在美国的 604,485 座桥梁中，大约 21% 是跨度为 6 m（20 英尺）或更大的涵洞。典型桥梁的额定载荷提出了许多挑战。由于涵洞独特的几何构造及其与土壤介质的相互作用，为非典型结构（例如埋拱形涵洞）制定额定载荷更为复杂。本文提出了一种用于在役钢筋混凝土 (RC) 拱涵额定载荷的替代分析方法，该方法克服了广泛使用的弹性框架概念的局限性，同时易于实施。所提出的分析方法使用拱结构和周围土壤介质的二维有限元模型。有限元模型首先在全尺寸 RC 拱涵的实验测试中得到验证，承受模拟活荷载。经验证的有限元模型被用于21个大填充钢筋混凝土拱涵的额定荷载分析。研究发现，对于填充量超过 2.43 m (8 ft.) 的拱涵，控制作用是顶部和臀部的弯矩。对于填土大于 3.05 m (10 ft.) 的涵洞，活荷载效应可以忽略不计。对具有该特性的涵洞提出了修订后的评级公式。