As part of this study, has been developed a numerical method which allows to establish abacuses connecting the normal force with bending moment for a circular section and therefore to predict the rupture of this type of section. This may be for reinforced concrete (traditional steel) or concrete reinforced with steel fibers. The numerical simulation was performed in nonlinear elasticity up to exhaustion of the bearing capacity of the section. The rupture modes considered occur by plasticization of the steel or rupture of the concrete (under compressive stresses or tensile stresses). Regarding the fiber-reinforced concrete, the rupture occurs, usually, by tearing of the fibers. The behavior laws of the different materials (concrete and steel) correspond to the real behavior. The influence of several parameters was investigated, namely; diameter of the section, concrete strength, type of steel, percentage of reinforcement and contribution of concrete in tension between two successive cracks of bending. A comparison was made with the behavior of a section considering the conventional diagrams of materials; provided by the BAEL rules. A second comparative study was performed for fibers reinforced section.

In this paper, we present an analytical model to analyze reinforced and prestressed concrete beams loaded in combined bending, axial load and shear, in the frame of non linear elasticity. In this model, the equilibrium of the beam is expressed by solving a system of equations, governing beams equilibrium, based on the stiffness matrix of the beam, which connects the load vector to the node displacements vector of the beam. It is built from the stiffness matrix of the section which takes into account a variation of the shearing modulus (depending on the shear variation) instead of assuming a constant shearing modulus as in linear elasticity. For the internal tendons, the stiffness matrix is completed by the terms due to the prestress effect in flexural equilibrium and by the balancing of one part of the shear by the transverse component of the force in the inclined cables.

Abstract-The flexural behavior of reinforced concrete beams is a well-known problem. In the classical studies about this subject, shear strength is neglected or taken into account by simple formula from the linear theory of elasticity, neglecting flexure and shear interaction. For this reason, these classical methods allow to predict only the flexural fracture modes, not the shearing fracture modes.We present in this paper an analytical model able to analyze reinforced concrete structures loaded in combined bending, axial load and shear in the frame of non linear elasticity. In this model, the expression adopted for the section's stiffness matrix does not take into account a constant shearing modulus G=f(E) as in linear elasticity, but a variable shearing modulus which is a function of the shear variation using simply formula. In this part, we present a calculus model of reinforced concrete beams on the three dimensions (3D). This model of computation is then expanded to spatial structures in the second part. A computing method is then developed and applied to the calculus of some reinforced concrete beams. The comparison of the results predicted by the model with several experimental results show that, on the one hand, the model predictions give a good agreement with the experimental behavior in any field of the behavior (after cracking, post cracking, post steel yielding and fracture of the beam).

Purpose The purpose of this study, is to deals with capacity design (strong column – weak beam) in reinforced concrete frames, slightly slender, which depends on the determination of a capacity ratio necessary to reach a structural plastic mechanism. To find the capacity ratio allowing to achieve a fairly ductile behavior in reinforced concrete frames, it is necessary to validate this concept by a non-linear static analysis (push-over). However, this analysis is carried out by the use of the ETABS software, and by the introduction into the beams and columns of plastic hinges according to FEMA-356 code. Design/methodology/approach This approach makes it possible to assess seismic performance, which facilitates the establishment of a system for detecting the plasticization mechanisms of structures. It is also necessary to use a probabilistic method allowing to treat the dimensioning by the identification of the most probable mechanisms and to take only those that contribute the most to the probability of global failure of the structural system. Findings In this study, three reinforced concrete frame buildings with different numbers of floors were analyzed by varying the capacity ratio of the elements. The results obtained indicate that it is strongly recommended to increase the ratio of the resistant moments of the columns on those of the beams for the Algerian seismic regulation (RPA code), knowing that the frameworks in reinforced concrete are widespread in the country. Originality/value The main interest of this paper is to criticize the resistance condition required by RPA code, which must be the subject of particular attention to reach a mechanism of favorable collapse. This study recommends, on the basis of a reliability analysis, the use of a capacity dimensioning ratio greater than or equal to two, making it possible to have a sufficiently low probability of failure to ensure a level of security for users.

Reinforced concrete frames with masonry infill are widely utilized in construction worldwide. This present study aimed to investigate the behaviour of masonry infill. Firstly, the compressive strength of the masonry infill and the evaluation methods were examined, specifically prism tests and wallette tests. The study collected a substantial database, revealing that wallette tests indicate higher stiffness compared to prism tests. Based on the findings, it is recommended to employ prism tests for assessing the stiffness of masonry and wallette tests for evaluating the compressive strength of masonry. Furthermore, the study assessed the performance of 18 empirical models to identify the most suitable model for predicting the compressive strength of masonry using the two testing methods (wallette and prism). To evaluate the strength of masonry infills under horizontal loading, a database of reinforced concrete frames with masonry infills was collected. The infill responses were determined by calculating the differences between the infilled frame and the bare frame. By employing multivariate regression analysis, equations were proposed for the various parameters of the quadri-linear relationship governing the behaviour of masonry infill. A comparison of the equations proposed in this present study with those present in the literature demonstrated their reliability.