ABSTRACT:

This paper presents a model of tensile fracture of concrete as heterogeneous material on the basis of the phenomenological approach. A criterion of destruction is the work for formation of a new fracture surface. The developed test method of experimental definition of tensile concrete characteristics is described. Results from the research of a fracture surface are presented. The obtained statistical data used at realization of the proposed model. The experimental research of the fracture process in a bent reinforced-concrete beam show, that it is possible to use the proposed criterion for forecasting work building constructions.

INTRODUCTION

Exploitation safety of sea hydraulic engineering reinforced concrete constructions is ensured by means of the regular monitoring of their surfaces. As regards the construction toughness, a crack in the concrete within a protection layer does not prevent normal exploitation of reinforced concrete constructions. At the same time, crack results in transition of process of concrete external corrosion in internal on the one hand, and, on the other hand, they are stress concentrators at the solution of a fatigue problem. Another very important problem is how to provide requirements to strength characteristics of constructional building materials for maintenance of reliability and safety of hydraulic engineering constructions during the whole exploitation period. The fracture mechanics enables the analysis of cracks origin and growth process in metal, ceramics and other materials. But application of theoretical and experimental fracture mechanics methods to an estimation of strength and durability of reinforced concrete constructions is hampered because of concrete structure singularities. A simple model for tensile fracture of concrete is proposed to include the heterogeneity of material on a macro scale. In this work we develop a new experimental method for finding concrete fracture characteristics. Then the characteristics are used in calculation of reinforced concrete construction.

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