箱形桥梁估算剪力滞效应的两种简捷方法

讨论两种估算超静定箱梁剪力滞效应的简捷方法。第一种方法，在受荷的超静定体系中取一基本静定体系，将梁上的载荷、反力分别作用于基本体系上，然后利用叠加原理求得剪力滞系数．即利用λ＝∑λｉλｉ，这里．Ｍｉ，λｉ分别表示基本体系中的指定截面上求得的静定结构弯矩及剪力滞系数。第二种方法是在受荷的超静体系中，根据弯矩图中的反弯矩割切成若干简文体系。指定截面上的剪力滞效应（或剪力滞系数），即在所在的简支梁上求得．最后通过两等跨常截面承受均布荷载的连续证明两种简捷方法计算结果相当吻合．同样证实这两种简捷方法在工程上实用有重要意义。

SHORT-CUT METHODS FOR EVALUATION OF SHEAR LAG EFFECT ON BOX GIRDER BRIDGES

wo short-cut methods were presented for the analysis of shear lag effect statically in indaterminate structure of thin-walled box girder bridges. One was based on the principle of superposition. Any indeterminate structure subjected to various kinds of loading can be replaced by a simply-supported system with redundantreactions as uplift load acting upon it. Shear lag coefficients(SLC) required on the givensection can be predicted by summing up the product of the SLC multipling the simplebeam moment at that sectinn in each case and then divided by the statically indeterminate moment on that section. The second was to discrete the indeterminatestructure into a series of simply-supported systems At inflection points of themoment diagram under the applied loadings. The SLC required at given section can bereadily obtained in the case of simply-supported beam. A worked example was presentedfor demonstration and comparison.