三角形ETFE双层气枕足尺试验研究

Experimental study on triangular ETFE double layer cushion

对边长为3.74m的三角形ETFE双层气枕进行充气和膜面堆载试验,利用激光位移计对上下层8个测点的膜面高度进行实时测量,并与数值模拟结果对比分析.研究了三角形ETFE双层气枕的成形过程及风、雪荷载作用下的力学性能,验证了基于单轴拉伸试验所得材料力学参数的正确性和利用非线性有限单元法进行ETFE气枕分析的适用性.研究表明:(1)内压或外荷载作用下,三角形ETFE气枕膜面变形对称性较好,膜面高度随着内压、外荷载的增大呈线性增加或减小规律;(2)在风、雪荷载作用下,三角形ETFE气枕内接圆区域膜面应力较大且分布均匀,角部是低应力区,容易形成垂直于对角线的褶皱;(3)在风、雪荷载作用下,膜面应力小于ETFE第一屈服强度,气枕处于线弹性工作状态,三角形ETFE气枕具有较好的抵抗外部荷载作用的能力.

Inflating and loading tests of a triangular ETFE double layer cushion with 3.74 mside length are carried out to investigate form-finding process and mechanical properties under wind and snow load.Membrane surface height is measured at eight points and compared with the result of numerical analysis.Material parameters obtained by uniaxial test and nonlinear finite element method are verified for the analysis of ETFE cushions.The results show that：（1）the membrane surface height increases or decreases linearly with the increase of internal pressure or external load,and the triangular ETFE double layer cushion deforms symmetrically under external load;（2）under the wind and snow loads,the membrane stress in the inscribed circle area of triangular ETFE cushion is large and distributes uniformly,while folds occur easily at the corners because of the low stress;（3）under the wind and snow loads,the membrane stress is less than the first yield strength of ETFE,air pillow is thus working at linear elastic state,and triangular ETFE cushions have a better ability to resist external loads.