拱形立体桁架结构振动台试验研究

Shaking table test of trussed arch structure

为研究拱形立体桁架结构在强震作用下的破坏模式,以一实际工程为背景,对拱形立体桁架结构进行缩尺比例为1/15的振动台试验。对模型相似比的选取、模型设计以及加载方案、测点布置等进行说明,得到各级人工波作用下,模型自振频率、阻尼比、加速度反应、位移反应以及杆件应变,研究模型自振特性的变化规律,获得拱形立体桁架结构在强震作用下的破坏模式。研究表明,随地震波峰值加速度的增大,结构各向自振频率和等效刚度降低,结构阻尼比增大。地震波向模型顶部传播过程中,加速度和位移响应随结构高度逐渐放大。当输入峰值加速度达到0.8g时,结构刚度迅速下降,主桁架斜腹杆大量屈曲;当输入峰值加速度达到1.0g时,结构刚度下降50%,发生平面内反对称变形。

Based on a practical engineering project, a shaking table test of a 1/15 scaled model was accomplished to obtain the failure mode of the trussed arch structure. The similitude relationship, design of the scaled structural model, instrumentation and test procedure were described. The experimental results of natural frequency, damping ratio, acceleration response, displacement response and member strain under the action of artificial waves were presented and analyzed in terms of the change rule of vibration characteristics and the failure mode of structure. The results show that, with the increase of peak ground acceleration, the natural frequency and equivalent stiffness of model will decrease obviously while the damping ratio increase. The acceleration and displacement responses are enlarged gradually as the seismic waves propagated to the top of the model. When the peak ground acceleration reaches 0. 8g, large numbers of main truss diagonals are buckled and the structural stiffness is declined rapidly. At the end of experiment, the structural stiffness is decreased by 50% and the main trusses has in-plane anti-symmetric deformation.