Preflex beam girders with remarkable advantages are widely used in bridge structures. With aging, preflex beam bridges undergo concrete cracking and degrade as the cracks propagate and deteriorate due to repeated service load application and exposure to humid and saline environment. The objective of this study was to evaluate concrete cracking, changes in prestress, and consequent changes in sectional properties as the preflex beam undergoes deterioration in its concrete casing under cyclic loading. The experimental study investigated the behavior of a preflex beam specimen under multiple cyclic loading ranges, reproducing different deterioration levels in the concrete casing of the specimen. Relating concrete deterioration to resulting changes in the girder’s structural behavior, the study outlined recommendations for monitoring approaches in actual bridges. The study concluded that with advancement in concrete deterioration, the preflex beam girder loses prestress that results in reduced strength of the girder and remarkable changes in its sectional properties. The study also concluded to minimize prestress loss and changes in sectional properties of the girder, closer spacing for shear ribs welded to the lower flange can be helpful.

具有显着优势的预弯梁被广泛应用于桥梁结构中。随着老化，预弯曲梁桥会发生混凝土开裂和退化，因为由于重复的服务载荷施加和暴露在潮湿和盐碱环境中，裂缝会扩展和恶化。本研究的目的是评估混凝土开裂、预应力的变化以及随着预弯曲梁在其混凝土外壳中在循环载荷下发生劣化而导致的截面特性的变化。实验研究调查了预弯曲梁试件在多个循环载荷范围内的行为，再现了试件混凝土外壳的不同劣化水平。将混凝土劣化与由此导致的梁结构行为的变化联系起来，该研究概述了在实际桥梁中监测方法的建议。研究得出的结论是，随着混凝土劣化的进展，预弯曲梁失去了预应力，导致梁的强度降低，其截面特性发生显着变化。该研究还得出结论，为了最大限度地减少预应力损失和梁截面特性的变化，焊接到下翼缘的剪力肋的间距更小可能会有所帮助。