带裂缝梁振动特征值灵敏度研究

本文用无质量弹簧模拟梁类结构中单侧裂缝引起的局部柔度，弹簧的转动刚度系数与裂缝高度有关，引入奇异函数，将裂缝处的转角间断表示为分布荷载作用，以弹性力学的变分原理为基础，推导出任意边界条件的带裂缝单跨梁的特征值灵敏度表达式，并讨论了裂缝引起的梁的振型变化，采用有限元法和本文方法对分别对简支梁进行动力分析，其计算结果吻合良好。

矩形钢管柱和混凝土弹簧刚度系数方程拟合研究

在矩形钢管混凝土柱内部设置传力构件以解决现有的钢管混凝土柱钢管与混凝土难以共同受力的问题。将弹性地基梁理论合理应用到设置传力构件的钢管混凝土柱,采用解析法求解混凝土工作承担系数时,钢管竖向弹簧刚度、钢管转动弹簧刚度、混凝土竖向弹簧刚度至关重要。3个弹簧刚度的求解均采用有限元法,对于实际工程的应用,比较繁琐不直观,且有一定难度。定义钢管竖向弹簧刚度系数、钢管转动弹簧刚度系数、混凝土竖向弹簧刚度系数,通过有限元模拟分析3个弹簧刚度系数的影响因素,分别得出各因素与3个弹簧刚度系数的拟合方程。考虑各因素间的耦合作用,修正拟合方程,回归总拟合方程,并进行误差分析。结果表明,3个弹簧刚度系数拟合总方程有效地解决了弹簧刚度的求解,为进一步求解混凝土工作承担系数提供了可靠的依据。

一个基于实验数据的两跨门式钢架计算机模型优化

文章以实验室模型的结构动力学参数以及初期实验数据为基准,对计算机模拟模型进行了二次模型优化尝试。第一次尝试根据模型的结构动力学特征,针对外部约束条件以及构件内部连接性质同时进行优化,大致确定了各约束以及连接的转动刚度数值。第二次尝试则根据初期实验数据,对其中柱中连接的转动刚度进行了更细致的调整。经过两次优化后,计算机模拟模型已初步具备拟合实验室模型动力学特征以及输入/输出对应的功能要求。

Higher mode effects in hinged wall with BRBsin base-frame structures using distributed parameter models

To investigate the effect of higher modes on the displacement and inner forces in HWBB(hinged wall with buckling-restrained braces in base)-frame structure,distributed parameter models for both the HWBB-hinged frame structure and the HWBB-MRF(moment resisting frame)structure are built.The hinged wall is simplified as a flexural beam.BRBs(bucking-restrained braces)are simplified to a rotational spring.MRF is simplified to a shear beam.Vibration equations of distributed parameter models are derived.Natural periods,natural modes of vibration,inner forces and displacements of the distributed parameter models are derived based on the vibration equations using numerical methods.The effect of the relative stiffness ratio and the rotational stiffness ratio on the higher mode effects is investigated.For elastic structures,the global displacement and shear in MRF are predominantly controlled by the first mode,while the shear and bending moment in the wall are significantly affected by higher mode effects.The effect of the yielding of BRB on the inner forces distribution in the HWBB-hinged frame is investigated.The results indicate that the first mode will no longer contribute to the inner forces and the contribution from higher modes to inner forces increases after the BRBs yield.Displacement is not sensitive to higher mode effects and it is controlled by the first mode after the BRBs yield.Parameter analysis demonstrates that the displacement amplitudes are reduced with the increase in the flexural stiffness of the wall before the flexural stiffness reaches a certain value.The first three periods decrease with the increase in the rotational stiffness.With the increase in the rotational stiffness ratio,the contribution from the first mode decreases while contributions from both the second mode and third mode increase.

半刚性连接高层钢框架P-△效应分析的简化方法

介绍一个半刚性连接高层钢框架P-△效应分析的实用简化方法。以部分框架为分析子单元,用变刚度的转动弹簧模拟梁柱节点连接的半刚性,建立了考虑P-△效应的半刚性连接高层钢框架内力和位移计算的无迭代简化公式。算例表明,梁柱连接的半刚性确实降低了钢框架的抗剪刚度,明显增加了结构的水平位移和P-△效应,应当在高层钢框架的P-△效应分析中考虑半刚性连接的影响。该方法不仅简单实用,便于手算,而且精度较高,可供工程设计人员在半刚性连接高层钢框架设计时使用。影响半刚性连接高层钢框架P-△效应的主要因素是柱的抗剪刚度、梁与柱的线刚度之比、半刚性连接的类型和相应的连接刚度系数α值。