Ana Yanakieva

Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

Abstract Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model’s plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

Modelling of the Bending Behaviour of a Double-Reinforced Beam from Recycled Materials for Application in NZEBs

A number of design approaches of nearly zero energy buildings (NZEBs) are known in literature. The aim of the present paper is to study the bending behavior of a structural bi-material element of a recycled concrete beam reinforced along its lower and upper side by highly-tough thin layers. On one hand, the design of such a structural element would produce a light weight element, since no conventional reinforcement would be involved, and on the other hand, the recycled aggregate of the concrete matrix would make the element applicable to NZEBs. Thus, natural energy resources may be saved. Moreover, thin reinforcing layers guarantee good bearing capacity due to their high toughness, excellent crack resistance under dynamic impacts, as well as fire resistance when fabricated from special polymer materials. The approach of employing such lightweight structural bi-material elements in constructions is energy saving and innovative. The study provides a method of specifying the thickness of the reinforcing layer assuming the existence of a transition area between the two materials and smooth transition between the reinforcing layer and the concrete bulk. It is also assumed that the element operates within the materials linear-elastic zone, without generation of macrocracks within concrete and debonding along the interface. The analytical results found are verified by subsequent experimental evidence available in literature.

Numerical Procedure for Identification of Constitutive Equations Based on Experimental Data

Abstract In this research experimental data obtained by well-known methods of displacement measurement are considered, whereas a thin cell meshwork has been fixed to the surface of the observed loaded object (thin metal sheet, for instance) and a set of point displacements has been ob- tained. Based on such experimental evidence, an eight point numerical procedure is proposed in the paper to identify the constitutive relations for small time increments. The presented approach is also applicable in case of micro deformations and facilitates the derivation of nonlinear constitutive equations in stress/strain increments. Approximate error es- timation of the procedure is additionally performed, and a test example is given.