Improved phenomenological modelling ofrntransient thermal strains for concreternat high temperatures

Several extensions to the Thelandersson phenomenological model for concrete under transientrnhigh temperatures are explored. These include novel expressions for the temperature degradation of thernelastic modulus and the temperature dependency of the coefficient of the free thermal strain. Furthermore,rna coefficient of thermo mechanical strain is proposed as a bi-linear function of temperature. Goodrnqualitative agreement with various test results taken from the literature is demonstrated. Further extensionsrninclude the effects of plastic straining and temperature dependent Poisson? ratio. The models performancernis illustrated on several simple benchmark problems under uniaxial and biaxial stress states.