In most Codes of practice,very simple formulae are given for the calculation of effective width. EC4(欧洲组合结构规范)proposed that the effective width on each side of the steel web should be L/8,but not greater than half the distance to the next adjacent web,not greater than the projection of the cantilever slab for edge beams. ·In Chinese design practice(中国规范)of composite beams,similar effective width is adopted given as the following where b,b,are effective width on each side of the steel web,be L/6
• In most Codes of practice, very simple formulae are given for the calculation of effective width. • EC4 （欧洲组合结构规范）proposed that the effective width on each side of the steel web should be L/8, but not greater than half the distance to the next adjacent web, not greater than the projection of the cantilever slab for edge beams. • In Chinese design practice（中国规范） of composite beams, similar effective width is adopted given as the following: • where b1 , b2 are effective width on each side of the steel web, be L/6, be b1 b2 b0
b 〔a)composite beam (b)composite beam with haunch Effective width of concrete slab 混凝土有效翼缘宽度
Effective width of concrete slab 混凝土有效翼缘宽度
4.5 Elastic analysis(弹性分析) 正常使用极限状态分析按弹性分析方法进行。 基本假定(1)钢、混凝土为理想线弹性，(2)平截面， (3)不计滑移，(4)不计混凝土板内钢筋 Checks must be made to ensure that at service loads, its deflection is not excessive and the stresses are within the elastic range. When elastic theory is used,it may be necessary to include the effects of creep and shrinkage of concrete, and of temperature,if accurate results are required
4.5 Elastic analysis (弹性分析) • 正常使用极限状态分析按弹性分析方法进行。 • 基本假定(1)钢、混凝土为理想线弹性，(2)平截面， (3)不计滑移，(4) 不计混凝土板内钢筋 • Checks must be made to ensure that at service loads, its deflection is not excessive and the stresses are within the elastic range. • When elastic theory is used, it may be necessary to include the effects of creep and shrinkage of concrete, and of temperature, if accurate results are required
Properties of concrete Time dependence of concrete properties,i.e., shrinkage and creep,should be considered when determining the response of composite structures under sustained loads,with particular reference to member stiffness. .A value of the modular is defined to account for the creep effect in the analysis: E、 Es nef= Ec.ef [Ec/(1+)] Ec.ef= an effective modulus of elasticity for the concrete a creep coefficient approximating the ratio of creep strain to elastic strain for sustained compressive stress
Properties of concrete • Time dependence of concrete properties, i.e., shrinkage and creep, should be considered when determining the response of composite structures under sustained loads, with particular reference to member stiffness. • A value of the modular is defined to account for the creep effect in the analysis: