原竹骨架喷涂复合材料多功能组合构件力学性能试验研究

为研究原竹骨架喷涂复合材料组合构件的力学性能,该文通过立柱轴压性能和抗弯性能足尺试验,研究其传力过程、承载能力、破坏模式及复合材料对原竹骨架的增强作用。结果表明:组合构件立柱轴压试验的破坏模式为整体失稳破坏;在有限元参数分析中,立柱数目少于6根时,立柱数目越多,平均每根立柱的轴压承载力越大,但立柱数目超过6根时,平均每根立柱的极限承载力随立柱数目的增多反而有降低的风险;立柱间距在200~500 mm范围内,间距越大,其立柱平均承载力越高;对多根立柱统一均匀加载时,构件会发生整体失稳破坏,而对中间立柱单根加载时,其顶部出现局部压溃现象。抗弯性能试验的破坏模式为纵向原竹与复合材料产生滑移,构件在集中荷载处发生弯折破坏。复合材料对构件立柱提供了较好的约束作用,使其轴压承载力提高3.7倍,但与立柱达到抗压强度破坏时的极限承载能力相比低16.7%;当达到组合构件的弯曲容许挠度和峰值挠度时,构件所承担荷载分别约为原竹骨架构件的7倍与4倍,说明复合材料对原竹骨架的增强作用显著。研究成果可为喷涂复合材料-原竹骨架组合结构体系的工程应用提供参考。

Experimental study on mechanical properties of multi-function bamboo skeleton composite members sprayed with composite material

Bamboo is a high-quality material that is light, strong, and grows quickly. Bamboo structures have the advantages of environmental protection, ecology, low carbon and so on. It is a renewable and environmentally friendly biomass building material that is easy to obtain. However, full culm bamboo is often used to construct rural low-rise houses and temporary structures such as scaffolding or pavilions. This is because the irregular geometry of bamboo causes problems in building form and component connection, while the traditional bamboo architecture has poor performance in fireproofing, heat insulation, sound insulation and so on. Bamboo is difficult to use in buildings to meet the requirements of comfort. In order to fully exploit the natural advantages of bamboo and overcome its deficiencies, a new type of multifunctional composite members which combines bamboo skeleton and composite material was presented. The composite material was mainly composed of a combination of mortar, polystyrene particles, and mineral adhesives. It is wrapped on the surface of the bamboo skeleton. Through the full-scale tests of multifunctional composite members, the process of force transfer, bearing capacity, failure mode and enhancement function of composite material were observed. The results showed that composite material provided a good binding effect and greatly improved the axial compressive bearing capacity of the composite members. However, there was still a gap between the above-mentioned ultimate bearing capacity and the strength failure result. The failure mode of the composite members was cracking of composite material on the side elevation. Because of slippage between composite material and bamboo studs, the restraint effect of the composite material on the studs was weakened, and the ultimate failure of the composite members was caused by instability. Analysis of finite element parameters showed that when the number of studs is less than 6, the axial bearing capacity of each composite members stud increased with the increase of the number of studs. Conversely, the axial bearing capacity of each composite members stud was reduced. When the spacing of the composite members studs were in the range of 200-500 mm, the average bearing capacity of the stud increased with the increase of spacing. When the composite members was loaded uniformly, the composite members was in a state of global buckling failure, but when the middle single composite members stud was loaded, the top of the stud appeared the phenomenon of local crushing. The failure mode of the bamboo skeleton sprayed with composite material was bending failure at joining of concentrated load, accompanied by slippage between bamboo and composite material, and the pressure was borne by composite material before 30 kN, with the increase of load, the pressure was borne by the top of bamboo. When the allowable deflection and peak deflection of the composite member are achieved, the bearing capacity of the composite member is about 7 and 4 times as much as that of the bamboo skeleton member, the composite material can greatly increase stiffness of the bamboo skeleton member, the proteiform disadvantage of bamboo subjected to bending can be overcome . The multifunctional bamboo skeleton member sprayed composite material has good performance, the results provided a reasonable basis for the theory and engineering application of composite member.