摘要
由厚度2mm以下冷弯薄壁型钢骨架和墙板组合而成的龙骨式复合墙体组成的“盒子式”结构体系是低层冷弯薄壁型钢住宅中一种富有特色的新型结构体系。本文针对这种龙骨式复合墙体在压弯作用下的破坏模式和极限荷载进行讨论研究和理论分析,并结合国内外现有的研究成果,提出龙骨式复合墙体压弯承载力的设计方法。
另一方面,这种冷弯薄壁型钢低层住宅体系均采用自攻螺钉连接,施工非常方便,实践证明也非常有效。本文针对其中的三种典型连接进行了理论分析和试验研究,包括梁梁连接、梁柱连接、抗拔件连接。
通过试验研究,本文得出以下结论,供实际工程参考:
1.在龙骨式复合墙体中,墙板材料对墙体整体承载力影响很大,立柱受到不同材料墙板的支撑效应可以通过立柱计算长度系数K值来体现。在两端铰接、墙体材料为波纹板和石膏板、压弯作用下,屈服强度为550MPa高强冷弯薄壁型钢复合墙体立柱的计算长度系数可取K=0.4;而墙体材料为OSB板和石膏板的Q235立柱计算长度系数可取K=0.2。石膏板和波纹板抗弯刚度远低于OSB板的抗弯刚度,后者能显著提高墙体的整体刚度。
2.对梁梁连接,等边角钢连接件通过自攻螺钉连接梁与梁的腹板。试验研究表明,该连接形式传力路径明确,连接承载力主要取决于自攻螺钉的抗剪强度。
3.对梁柱连接,由于梁截面腹板高厚比较大,连接处腹板加劲肋的摆放位置对连接承载力影响很大。试验研究表明,加劲肋在梁外侧,或加劲肋在梁内侧且与梁下翼缘无接触时,连接传力非常不充分;当加劲肋置于梁截面内且顶紧下翼缘时连接的承载力最高。
4.对抗拔件连接,抗拔件厚度高,整体刚度远大于立柱截面。试验表明,连接部分的承载力主要取决于自攻螺钉的数量及被连接构件的截面强度。
The keel compound wall of a "box" structure has become a growing trend for lower steel residences around the world. It is most notable composed of cold-formed thin-walled steel (less than 2mm) and wallboard. Based on the failure mode and load-carrying capacities of the Wall-Stud system through several experiments, a design method of optimal load-bearing capacities of the keel compound wall system subjected to compression and bending load was presented.
Meanwhile, the application of screws has already been proven to be both convenient and efficient on the joints of stalloy. Experiments on typical joints between beams and columns including beam-beam, beam-column and tension equipment have also been carried out for the theoretical analysis.
Based on a series of tests, several conclusions can be drawn as follows:
1. The contribution of the wallboards towards the overall rigidity of the compound wall is very important. Additionally, the length factor k of the stud embodies the bracing affection of different wallboards. By the hinged connection, the length factor k of the stud of G550 composite wall system with corrugated board and plasterboard equals 0.4 while the stud of the Q235 composite wall system with OSB equals 0.1.
2. For the joint of beam-beam, the web of the beam is connected by equal angle steel fasteners with screws. The route of the force is simple and the capacities of the joints depend on the shearing strength of the screws.
3. The location of the stiffener for the web of the beam is most influential on the capacity of the beam-column joints. The transmission of the force is not efficient when either the stiffener is outside the beam or there is no-contact with the lower flange of the beam. So, the most efficient way to increase the capacity of the joint is when the stiffener is placed on the beam and touches the lower flange of the beam in close proximity.
4. Because of the great thickness and rigidity of the tension device, the capacity of the joints is dependent on the strength of the members that are connected.
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