一区二区不卡久久精品,人人狠狠综合久久亚洲,操亚洲,天天干天天操天天拍,黄色毛片在线观看,亚洲免费电影网站,草β好视频

A structure formed by connecting rods with hinges at both ends. The truss is composed of straight rods and generally has a plane or space structure with triangular members. The truss members mainly bear axial tension or pressure, so that the strength of the material can be fully utilized. When the span is large, the material can be saved compared with the solid web beam, and the weight and can be reduced but increase stiffness. Common trusses shapes are: triangular trusses, trapezoidal trusses, polygonal trusses, hollow trusses, and truss bridges.