竖向地震动强度包络函数的空间变化规律

利用SMART 1台阵三次地震记录拟合了各个测点在地震中的竖向地震动强度包络曲线及Amin 和Ang的强度包络函数中各模型参数值,分析了各模型参数的空间变化规律,建立了各模型参数随二维空间坐标及土层厚度变化的随机模型,为多点地震动合成中竖向强度包络函数的计算提供了理论依据。     

同一测点不同地震动分量空间相干性分析

利用SMART-1台阵的3次地震记录计算了同一测点三平动地震动分量问的相干值,并提出了相干函数模型。分析表明,同一测点各地震动分量间是低相干的,随频率衰减不明显;两水平分量问的相干性比水平分量与垂直分量间的相干性大。因此在工程计算中不计相干函数随频率的变化不会带来太大的误差。     

Degradation and Mechanism of the Mechanics and Durability of Reinforced Concrete Slab in A Marine Environment

An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete (RC) slab at different ages in a marine environment. Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab. In the first stage, cracks appear. In the second stage, cracks develop from the edges to the middle of the slab. In the third stage, longitudinal and transverse corrosion-induced cracks coexist. The corrosion ratio of reinforcements nonlinearly increases with the age, and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established. The flexural capacity of the corroded RC slab nonlinearly decreases with the age, and the model for the bearing capacity factor of the corroded RC slab is established. The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio. Finally, the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.     

砂浆-花岗岩界面动态轴向拉伸力学性能试验研究

骨料-砂浆界面过渡区的力学性能对混凝土宏观受力特性有很重要的影响。在MTS试验机上对40个砂浆-花岗岩交界面试件进行了动态轴向拉伸力学性能试验研究,分析不同应变率（10-6～10-2 s-1）、不同程度预静载（30%、50%、70%静载强度）以及往复荷载（1、5 Hz）对交界面动态轴向拉伸力学性能的影响,并对其动态破坏机制进行了初探。研究结果表明：①交界面动抗拉强度随应变率增加有明显增加趋势;②较小预静载（不超过50%）不仅没有使动抗拉强度降低,反而有可能提高动抗拉强度,较大的预静载对损伤弱化效应起主导作用,从而使动抗拉强度降低;③往复荷载作用下会出现明显的低周疲劳损伤,而且残余变形随往复荷载的频率增加而减小;④不同应变率下的交界面应力-应变曲线上升段类似,约50%强度后呈现非线性变化,但非线性程度随应变率增加趋向不明显。另外,尝试性地进行了交界面试件轴向拉伸应力-应变全曲线的试验,得到了稳定断裂的全过程曲线。     

最大峰值加速度与有效峰值加速度的大小比例关系及影响因素探讨

分别以最大峰值加速度(以下简称PGA)和有效峰值加速度(以下简称EPA)为参数,对金沙江流域上12个工程场点进行了地震危险性分析,得到了各个场点在不同的年超越概率下的基岩PGA和EPA值。通过对PGA、EPA值比较分析认为:PGA与EPA值的大小比例关系主要受年超越概率大小的影响,当年超越概率较大时,表现为PGA>EPA;当年超越概率较小时,PGA与EPA的比例关系还与场点周围的潜源分布形式及潜源的震级上限的大小有关,不同的年超越概率、不同的潜源分布形式和震级上限,可使PGA>EPA,也可使PGA相似文献