CALCULATION AND ANALYSIS OF CREEP MULTIPLIER OF COMPOSITE BEAMS IN EUROCODE 4
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摘要: 欧洲标准4(EN 1994-2)将徐变不利影响表示为混凝土弹性模量的折减系数,该系数是用定值徐变因子和徐变系数表示的时间的函数。但定值徐变因子不能反映钢梁高度等重要参数,有必要推导解析算式作为补充。基于徐变微分本构方程,在合理简化基础上推导轴压徐变因子和弯曲徐变因子的算式,分别用于换算混凝土等效钢的面积和惯性矩。通过微分方程组的电算解验证,这两个算式可行。对钢梁高度进行参数分析,结果表明:EN 1994-2的折减系数符合组合梁挠曲刚度随时间增长而降低的规律,但会低估各种不利影响,而且随着钢梁高度的增加偏差加大。Abstract: In Eurocode 4, adverse effects of creep are expressed as the reduction factor of concrete elastic modulus, which is the function of time including a constant creep multiplier and creep coefficient. However, the constant creep multiplier can not reflect important factors such as the beam height, it is necessary to derive analytical formula as a supplement. Based on Dischinger creep differential constitutive equation, formulas of axial creep multiplier and bending creep multiplier were derived after a reasonable simplification, which could be used to transform the area and moment of inertia of concrete into those of the equivalent steel respectively. Through the computer solution of differential equations, the two formulas were verified. Parameter analysis was carried out on the beam height, the results showed that reduction factor in Eurocode 4 was recommended for the conformity with the time-dependent law of composite beams, but it underestimated the adverse impact and the errors increased with the increased of steel beam height.
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Key words:
- steel-concrete composite beam /
- axial creep multipier /
- bending creep multipier /
- stress /
- deflection
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