论文部分内容阅读
温室、塑料棚构件主要是梁、柱、拱、刚架等几种形式。不管是那种形式,在实际生产中都必须满足以下三方面的要求。1.要有足够的强度。构件的强度是指其抵抗外力的能力,对于任何一种构件来说,都必须能够安全地承担外力的作用而不致破坏,并有足够的强度储备。2.要有足够的刚度。构件在外力作用下,都会产生一定程度的变形,过大的变形往往影响构件的使用。因此构件受外力作用后所产生的最大变形,必须在规定范围内。例如,一般梁允许挠度是跨度的1/150—1/200。3.要有足够的稳定性。构件虽然受外力作用时,发生变形,但仍然能保持它原来的几何形状,不致由于变形而突然偏斜,丧失承载能力。一、梁的计算和设计为保证梁的安全使用,就要使梁受力作用后产生的最大应力不超过它的容许应力[σ],它的最大挠度不超过容许挠度[f/L]。因此,梁的强度和刚度计算公式如下:
Greenhouses and plastic sheds are mainly constructed of beams, columns, arches, and rigid frames. Regardless of the form, the following three requirements must be met in actual production. 1. Have enough strength. The strength of the component refers to its ability to withstand external forces. For any component, it must be able to safely assume the role of external forces without damage, and have sufficient strength reserves. 2. Have enough stiffness. Under the action of external forces, the components will have a certain degree of deformation. Excessive deformation often affects the use of components. Therefore, the maximum deformation of a component after it is subjected to an external force must be within the specified range. For example, the general allowable deflection of the beam is 1/150—1/200 of the span. 3. Must have sufficient stability. Although the component undergoes deformation when it is subjected to an external force, it can still maintain its original geometry without sudden deflection due to deformation and loss of bearing capacity. First, the calculation and design of the beam To ensure the safe use of the beam, it is necessary to make the maximum stress generated by the force of the beam not exceed its allowable stress [σ], and its maximum deflection does not exceed the allowable deflection [f/L]. Therefore, the strength and stiffness of the beam are calculated as follows: