温室用轻型方钢管柱脚底板压力及其简化计算模型

为研究半刚性柱脚底板压力分布,以轻型方钢管柱脚底板为研究对象,首先利用数值模拟方法,考虑柱脚与混凝土基础间非线性静力接触效应,针对4种加劲肋布置方式、6种偏心矩,分别计算24个轻型方钢管柱脚模型的底板受力情况,得到了底板压力分布规律,在此基础上提出了三折线底板压力分布模型,给出了轻型方钢管柱脚底板压力简化计算模型,并确定了相应关键参数。将简化计算模型结果与数值模拟、基于Winkler弹性地基梁模型的解析解和三角形压力分布的底板压力计算结果相对比。结果表明:三角形压力分布计算得到的底板最大压力值位于底板端部,而数值模拟、解析解及该文简化计算模型得到的最大压力值均位于柱截面翼缘处,且三角形压力分布的底板压力最大值明显大于该文简化计算模型结果,简化计算模型计算的底板压力最大值与数值模拟结果较为接近,且二者与解析解底板压力分布曲线亦吻合良好(误差大约为10%)。研究成果为轻型方钢管柱脚设计提供了更为精确适用的计算方法。

Pressure on base plate of lightweight square steel tube column for greenhouse and its simplified calculation model

Abstract: Prefabricated light steel structures have been widely used in multi-span greenhouses, agricultural facilities structures, temporary prefabricated building structures, and simple infrastructures due to its light weight, simple structure, and quick construction. Thin-walled square steel tube columns are good for two-way performance of a frame structures and becomes the most common structure member in a light steel structure. The column base is an important structure member to transfer the load in a light steel structure. Uneven distribution of the column base rigidity leads to nonlinear distribution of pressure on the base plate. It is important to achieve pressure distribution on the base plate for analyzing base rotation stiffness, ensuring bearing capacity of base and base plate, and preventing local compression failure of the concrete foundation. To present the pressure distribution of a semi-rigid base plate, taking a light square steel tube column base plate for example, 24 base models with 4 ribbed stiffener types and 6 eccentricity values were calculated by a numerical simulation method with consideration of the nonlinear static contact effect between base and concrete foundation. The base plate pressure distribution was obtained. Then a tri-linear model of base plate pressure distribution was achieved. At the same time, a simplified calculation model of light square steel tube column base plate pressure was proposed, and the corresponding key parameters were determined. The base plate pressure calculated by this simplified calculation model was compared with that by a numerical simulation, an analytical solution based on a Winkler elastic foundation beam model, and a triangular pressure distribution. The results showed that the maximum base plate pressure value calculated by a triangular pressure distribution locates the base plate end. That by numerical simulation, analytical solution, and the simplified calculation model all locates the column flange. The maximum base plate pressure value calculated by the simplified calculation model was obviously lower than that obtained by triangular pressure distribution, but close to that obtained by numerical simulation. Base plate pressure distribution curves calculated by the simplified calculated model, numerical simulation, and analytical solution met well with each other. The tri-linear simplified calculation model of light square steel tube column base plate pressure had the following three sections: base plate displacement within the scope of the two-column flange was one straight line, and that outside column flange was another two straight lines. The slope ratios of the two straight lines outside column flange and the one straight line within the scope of column flange were respectively 1/4 and -1 respectively. The fruits put forward an accurate and efficient base plate pressure calculation method for a light square steel tube column base design.