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Experimental study on exposed steel column bases connected to riser foundation concrete

外露钢柱底座与立管基础混凝土连接试验研究

基本信息

批准号：
03650469
负责人：
NAKASHIMA Shigetoshi
金额：
$ 1.22万
依托单位：
Osaka Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

It is known that the ultimate strength of an exposed type column base greatly depends on the bearing strength of concrete under the base plate. Experimental studies on concrete bearing strengh have been carried out for many years, but they mostly deal with reduced size models which have no reinforcement, and rarely use full scale models.This study, however, achieved a life-size under -stress representation of the bottom surface of the exposed type column base plate, and evaluated its bearing strengh.From this experiment, the following facts were clarified.If the edge distance remains the same, as the bearing width decreases, the bearing strength ratio increases. If the bearing width remains the same, as the edge distance increases, the bearing strengh ratio increases. The bearing strength is generally given in the following formula. sigmab/sigmac=alpha(Ab/Ae)^<beta>,sigmab : Bearing stress, sigmac : Cylinder compressive stress of concrete, Ab : Bearing area, Ab=b*x, Ae : Effective supporting area, Ae=(b+2e)*(x+2e), alpha, beta : Coefficients determined by experiment.The mean values of coefficients (alpha and beta)in this experiment were as thus calculated to be alpha=0.86 and beta=-0.441, respectively.On the other hand, compressive stress distribution under the bass plate bottom surface is assumed to be rectangular, the above relationship was then used to obtain a relation between the axial compression on the bearing area and the bending moment due to eccentricity of the gravity of them. Then, a new method to evaluate the ultimate strength of the exposed type column base, based on the experimental result is proposed. Values obtained using this method closely match the experimental values.

众所周知，外露式柱脚的极限承载力在很大程度上取决于底板下混凝土的承载力。混凝土承载力的试验研究已进行多年，但大多是在不加钢筋的缩尺模型上进行的，很少采用足尺模型。本研究对外露式柱底板底面进行了真实尺寸的受力模拟，并对其承载力进行了评价。在边缘距离相同的情况下，随着支承宽度的减小，支承强度比增大。如果支承宽度保持不变，则随着边缘距离的增加，支承强度比增加。承载强度一般用下式给出。sigumab/sigmac = alpha（Ab/Ae）^，sigumab：<beta>支承应力，sigmac：混凝土圆柱体压应力，Ab：承载面积，Ab = B * x，Ae：有效支承面积，Ae =（B +2e）*（x +2e），alpha，beta：由实验确定的系数。系数的平均值因此，在该实验中，α和β分别计算为α = 0.86和β =-0.441。假定底板底面下的压应力分布为矩形，利用上述关系式，得到了支承区轴向压力与重力偏心引起的弯矩之间的关系。在此基础上，提出了一种基于试验结果的外露式柱脚极限承载力计算方法。使用该方法获得的值与实验值非常吻合。