By using proper ply design and fixing a serf-designed guide device to the inlet of the mould, and improving the fiber inletting method of the pultrution technique, the FRP thin-walled beam was realized through pultrution by completely using ±45°fiber fabric as the prepreg of the web plate, so that there were completely ±45° ply structure in the web plate of the pultruded thinwalled beam. Comparative bending experiments on 4 different ply structures of FRP beams were executed. The results showed that comparing to the thin-walled FRP beams with complete 0° ply, the ultimate bearing capacities of the beams of which the webs adopt ±45°ply increased obviously. With increasing ±45° plies and decreasing 0° plies, the bending modulus of the beams declined by some extent. Since the web shear strength was improved, the shear failure of web was no longer the main failure mode of the thin-walled FRP beams, and local failure would become the overall bearing capacity bottleneck of this kind of beams instead.%采用适当的铺层设计和在模具口加装自主设计的导向装置,并改进拉挤工艺的进丝方法,然后通过拉挤工艺完全采用±45°纤维缝编毡作为型材腹板的预浸料生产纤维增强复合材料(FRP)薄壁梁,从而使FRP薄壁梁腹板为全±45°铺层结构.随后进行了4种不同铺层结构的FRP梁的对比弯曲试验.结果表明,与全0°铺层的FRP薄壁梁相比,腹板采用±45°铺层的梁的极限承载力提高明显;随着±45°铺层的增加和0°铺层的减少,梁的弯曲弹性模量则有所下降;腹板剪切强度提高之后,腹板剪切破坏不再是FRP薄壁梁的主要破坏形式,局部强度破坏将成为制约梁整体承载力的瓶颈.
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