Experimental and statistical research of secant modulus of heavy concrete deformations at long central compression by varying intensity loads

There are given the results of experimental and statistical studies of secant stress-strain modulus of heavy concrete with a long central compression load of varying intensity. The statistical analysis of the results for the long-term testing of heavy concrete allowed to establish a reliable linear correlation between secant stress-strain modulus Еh ,t,t and the initial level of stress ht in the long central compression under constant pressure st . The linear relationship Eh ,t,t ¢ -ht allowed to receive the theoretical value of secant modules of complete deformations Еh ,t,t under relative initial stress st =0 - Еo,t,t and cd = f st - ERt,t ¢ with corresponding jo,t,t initial value and j R,t,t boundary value of creep characteristics for heavy concrete. We received analytical dependence for the theoretical value of the secant modulus of complete deformation for heavy concrete Eh,t,t ¢ under constant squeezing load the initial level of stress ht <0,9fcd at any time of its action (t -t ). Scalar parameters values being the part of analytic dependence have been received from the correlation analysis of dependence Eh,t,t ¢ - ht and approximation of experimental correlation curves jo,t,t and j R,t,t over time. Concrete and reinforced concrete structures are main modern building materials. That is the reason for precise attention to calculations and design of such structures. One of the most important issues is the study of stressed-strain state of constructions during long-lasting pressure of different intensity. The authors demonstrate results of experimental and statistic studies of performance of heavy concrete under long-lasting compressive load. Based on the above, the linear correlative dependence between the secant modulus of full deformations Eh,t,t ¢ and initial relative stress level t t t s h cd , f = was defined. Based on linear dependence Eh,t,t ¢ -ht theoretical figures of secant modulus of deformations Eh,t,t ¢ for relative initial stress level were obtained, ht =0 - Еo,t,t and cd = f ht - ER,t,t ¢ corresponding to initial jo,t,t and limiting j R,t,t creep characteristics. Based on correlation analysis of dependences Eh,t,t ¢ -ht and approximation of experimentalcorrelative curves jo,t,t and j R,t,t in time the hyperbolic dependence was obtained to define secant modulus of total deformation of heavy concrete Eh,t,t ¢ under compressive load of level ht < 0,9fcd at any time (t -t ). The obtained results Eh,t,t ¢ as for the suggested dependence were compared with experimental figures. Deviation did not exceed 10%