The paper presents analysis of the stress-strain behaviour due to creep in statically determinate composite steel-concrete beam according to Eurocode 2, ACI209R-92 and Gardner&Lockman models. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law of Boltzmann-Volterra for the concrete part considering the above mentioned models. On the basis of theory of the viscoelastic body of Maslov-Arutyunian-Trost-Zerna-Bažant for determining the redistribution of stresses in beam section between concrete plate and steel beam with respect to time ‘t‘, two independent Volterra integral equations of the second kind have been derived. Numerical metod based on linear approximation of the singular kernel function in the integral equation is presented. Example with the model proposed is investigated. and Obsahuje seznam literatury
The paper presents analysis of the stress and deflections changes due to creep in statically determinate composite steel-concrete beam. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law of Boltzmann-Volterra for the concrete part. On the basis of the theory of the viscoelastic body of Arutyunian-Trost-Bažant for determining the redistribution of stesses in beam section between concrete plate and steel beam with respect to time ‘t‘, two independent Volterra integral equations of the second kind have been derived. Numerical method based on linear approximation of he singular kernal function in the integral equation is presented. Example with the model proposed is investigated. The creep functions is suggested by the ACI 209R-92 model. The elastic modulus of concrete Ec(t) is assumed to be constant in time ‘t‘. The obtained results are compared with the results from the model CEB MC90-99. and Obsahuje seznam literatury
The paper present analysis of the stress changes due to creep in statically determinate composite steel-concrete beam. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. and elastic law for the steel part and an integral-type creep law of Boltzmann-Volterra for the concrete part. For determining the redistribution of stresses in beam section between concrete plate and steel beam with respect to time t, Volterra integral equations of the second kind have been derived, on the basis of the theory of the viscoelastic body of Arutyunian-Trost-Bazant. Numerical method, which makes use of linear approximation of the singular kernal function in the integral equations is presented. Example with the model proposed is investigated. The creep functions is suggested by the 'CEB-FIP' models code 1990. The elastic modulus of concrete Ec(t) is assumed to be constant in time t. and Obsahuje seznam literatury