设置传力构件的矩形钢管混凝土柱轴压性能分析

采用有限元软件ABAQUS,对不考虑钢管壁与核心混凝土的粘结,只设置传力构件的矩形钢管混凝土轴压柱进行研究分析。分析核心混凝土及钢管壁的轴力-竖向位移曲线,得出设置传力构件的矩形钢管混凝土柱的轴力-竖向位移曲线及混凝土工作承担系数。通过对轴压作用下设置传力构件的矩形钢管混凝土柱性能的研究分析,验证了可采用CECS159∶2004《矩形钢管混凝土结构技术规程》的相关规定对设置传力构件的矩形钢管混凝土柱的轴压承载力进行计算。

预应力混凝土管桩的抗震设计探讨

简要介绍了预应力混凝土管桩的特点,分析其在地震荷载作用时桩基础所受到的外力包括应力、弯矩、形变等,并在参考国外相关规范基础上,得出抗震设计的计算公式。对于预应力混凝土管桩的抗震设计有一定的指导意义。

A Theoretical Analysis of the Bearing Performance of Vertically Loaded Large-Diameter Pipe Pile Groups

This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of both a single pile and pile groups.Considering the pile group effect and the skin friction from both outer and inner soils,an analytical solution is developed to calculate the settlement and axial force in large-diameter pipe pile groups.The analytical solution was verified by centrifuge and field testing results.An extensive parametric analysis was performed to study the bearing performance of the pipe pile groups.The results reveal that the axial forces in group piles are not the same.The larger the distance from central pile,the larger the axial force.The axial force in the central pile is the smallest,while that in corner piles is the largest.The axial force on the top of the corner piles decreases while that in the central pile increases with increasing of pile spacing and decreasing of pile length.The axial force in side piles varies little with the variations of pile spacing,pile length,and shear modulus of the soil and is approximately equal to the average load shared by one pile.For a pile group,the larger the pile length is,the larger the influence radius is.As a result,the pile group effect is more apparent for a larger pile length.The settlement of pile groups decreases with increasing of the pile number in the group and the shear modulus of the underlying soil.

3D finite elements analysis of vertically loaded composite piled raft

In recent years,a new type of foundation named composite piled raft foundation (also called long short composite piled raft) has been developed.Where designing shallow foundations would mean unacceptable settlement,or other environmental risks exist which could impair the structure in the future,composite piled raft foundations could be used.Finite element method was applied to study the behavior of this type of foundation subjected to vertical loading.In order to determine an optimal pile arrangement pattern which yields the minimum settlement,various pile arrangements under different vertical stress levels were investigated.Results show that with increasing the vertical stress on the raft,the effectiveness of the arrangements of short and long piles become more visible.In addition,a new factor named "composite piled raft efficiency" (CPRE) has been defined which determines the efficiency of long short piles arrangement in a composite piled raft foundation.This factor will increase when short piles take more axial stresses and long piles take less axial stresses.In addition,it is found that the changes in settlements for different long short piles arrangement are in a well agreement with changes in values of CPRE ratio.Thus,CPRE ratio can be used as a factor to determine the efficiency of piles arrangements in composite piled raft foundation from the view point of reducing raft settlements.