【作者】 王旭东；

【导师】 王培军；

【作者基本信息】 山东大学 ， 结构工程， 2015， 硕士

【摘要】 蜂窝梁通过将H型钢梁沿腹板曲线切割,然后错位焊接制成。蜂窝梁不仅增大截面高度提高抗弯承载力,而且便于布置管道穿线降低建筑层高,广泛应用于厂房、车库、桥梁等大跨建筑。本文提出一种新型圆角多边形孔蜂窝梁,与多边形孔相比,孔角修圆减小应力集中；与圆形孔蜂窝梁相比,一次切割提高制作效率。采用有限元方法,对圆角多边形孔与传统孔形蜂窝梁的受力性能进行了比较。该孔形蜂窝梁孔间腹板的屈曲性能仅稍低于圆孔蜂窝梁。不同防火保护方式将影响蜂窝梁孔间腹板的温度分布,进而影响其在火灾下的受剪屈曲性能。采用有限元传热分析,研究了全保护蜂窝梁和部分保护蜂窝梁孔间腹板的温度分布。由于部分防火保护情况下,孔洞厚度方向未保护,孔间腹板沿截面高度方向和钢梁纵向均存在温度梯度。对全保护蜂窝梁,随着防火保护层厚度的增大,钢梁耐火时间线性增加；但对部分防火保护蜂窝梁,当防火保护层厚度大于30mm后,增加防火保护层的厚度,已不能有效延长耐火时间。利用有限元方法对常温及火灾下圆角多边形孔蜂窝梁的孔间腹板屈曲性能进行研究,提出了修正的斜压柱模型用于常温下蜂窝梁的孔间腹板受剪屈曲承载力计算和火灾下孔间腹板受剪屈曲时的临界温度计算。研究的主要参数包括孔间距和腹板厚度。在参数分析的基础上,对斜压柱的有效宽度和作用于斜压柱上的有效压力计算方法进行了修正。修正的斜压柱模型可较准确计算蜂窝梁孔间腹板的受剪屈曲承载力和火灾下孔间腹板发生受剪屈曲破坏时的临界温度。完善了火灾下蜂窝梁孔间腹板屈曲破坏的设计体系,为常温和火灾下蜂窝梁的设计提供理论依据。更多还原

【Abstract】 Castellated steel beams are rolled steel H sections with regular circular or polygonal openings along their length. The beams are produced by cutting and re-welding rolled beam sections. An increase in beam depth provides greater flexural rigidity and strength to weight ratio. The openings allow service integration within the beams depth, which advantageously reduces, indirectly, the height of floors. The use of castellated steel beams has resulted in plant buildings, garages, bridges and longer span floors. In this paper, a novel castellated steel beam with fillet corner hexagonal web openings is proposed. Compared with castellated beams with polygonal openings, the stress concentration at the corner of the hole is reduced. Compared with castellated beams with circular openings, the manufacturing process only needs once cutting. The shear performance of the novel castellated beams is compared with that of traditional castellated beams by means of finite element method. The buckling behavior of the proposed castellated beams is slightly lower than that of castellated beams with circular openings.Different fire protected conditions can affect the temperature distributions in web-posts of castellated steel beams, thus affecting the buckling behavior of beams under shear force in a fire. Temperature distributions in web-posts of fully and partially protected castellated steel beams at elevated temperatures in a fire are investigated through the heat transfer analysis. For the partially protected beams, there are temperature gradients in web-posts along the vertical section and the horizontal section, which is due to the hole edge being left unprotected. The fire resistance time of fully protected beams increased linearly with the increase in fire coating thickness. However, for the partially protected beams, the fire resistance time cannot be effectively prolonged by increasing the thickness of fire protection when the thickness is more than 30mm.Web-post buckling behaviors of castellated steel beams with fillet corner web openings at ambient temperatures and elevated temperatures are investigated through the finite element method. A modified strut theoretical model is proposed for calculating the shear buckling capacity of castellated beams at ambient temperatures and the critical temperature at web-post buckling failure of castellated beams at elevated temperatures. The main parameters of opening distance and web thickness are studied in the present paper. The effective width and compressive force of the strut are modified based on the parametrical analyses. The modified strut model can relatively accurately calculate the critical bucking stresses of the web-post both at ambient temperatures and elevated temperatures. The design system on web-post buckling failure of castellated steel beams in a fire is be perfect, which provides evidence for design of castellated beams at ambient temperatures and elevated temperatures.更多还原