EFFECT OF REINFORCEMENT ON THE FAILURE LOAD OF RC BEAMS

2016

The optimum design of reinforced concrete members is found according to required security measures which are defined with respect to internal forces in the critical section resulting from loading conditions. For that reason, the length of spans and number of supports are effective on the optimum cost of the RC continuous beams. In this study, the optimum cross section dimensions and detailed optimum reinforcement design were investigated for different number of supports and spans. The optimum design was performed according to the design constraints given in ACI-318 (Building Code Requirements for Structural Concrete). All live load distribution patterns were considered and the analyses of RC beam were done by using Clapeyron's three moment equations. A random search technique (RST) was employed in order to minimize the material cost of the continuous beams with different number of spans.

Open Engineering

This work presents finite element (FE) modeling using the ABAQUS program to investigate the effect of steel reinforcement with three different types of high-strength steels, grades 420, A1035, and SD685 on the flexural behavior of RC beams under monotonic loading. Experimental findings from the literature have been used to validate the proposed model. The numerical load, deflection, mode of failure, failure concrete strain, and bottom steel strain at failure of 24 numerical specimens with collapsed conditions of tension-controlled, balanced, and compression-controlled are recorded. Also, the effect of compression reinforcement is being investigated. The results reveal that the flexural behavior of the experimental test for the three steel grades is well validated by FE analysis. The ductile and brittle behavior features of yield strength (YS) larger than 420 can be predicted for specimens designed according to current standards ACI-318M-19. Also, the compression reinforcement improv...

Journal of Engineering Science and Technology, 2018

The test result of an experimental study on the flexural strength of reinforced concrete beams strengthened with steel plates is presented. The beams were simply supported and loaded monotonically with two point loads. The test variables used in this study were strengthening method and development length of steel plates. Nine beams without strengthening and nine beams strengthened with steel plates were tested until the beams reach the flexural failure specified by crushing of concrete on the top surface of compression region. The test results show that steel plates increase the capacity of the beam significantly and slightly increase the flexural stiffness of the beams. In addition, the ultimate load of the strengthened beams with debonding failure was similar to the beams without strengthening if the load kept increasing until flexural failure. The test results also showed that the debonding failure occurred after the steel plate reach the yield stress value and the development le...

Mechanics Research Communications, 2014

The paper presents the results obtained from a finite element analysis compared with those of an experimental investigation carried out on a set of reinforced concrete beams externally strengthened to flexure. An innovative steel reinforced grout system with two different external reinforcement (with and without end anchorages) was used to evaluate the effectiveness of the strengthening system. A multi-crack concrete model and a delamination damage model for the interface between concrete and external reinforcement were adopted. All the beams were extensively instrumented and tested under four-point bending. Loads at concrete cracking, yielding of tension steel and at ultimate, as well as, strains in compression concrete, tension steel and external reinforcement, were detected and compared with the numerical results. The performance of the strengthened beams, in terms of load-deflection curves, strength and ductility, was also evaluated and compared with those of the control beam to highlight the main parameters which affect the mode of failure and the overall behavior of the structural elements. Finally, in order to study the structural behavior of different types of strengthened beams a parametric analysis has been developed.

Journal of Advanced Concrete Technology, 2021

The authors have reported from experimental investigation that the use of closed stirrups, U-shaped stirrups and rod-shaped reinforcements as shear reinforcements in reinforced concrete (RC) beams results in clear differences in internal crack patterns and maximum strength. In this study, simulations of the experimental beams were performed using a three-dimensional rigid-body spring model, demonstrating that the behavior observed in the experiments is a mechanical phenomenon that can be reproduced numerically. Using the stress distribution over the beam cross section obtained from the analysis, the beam and arch action components of shear resistance are decoupled and considered from the perspective of the shear resistance mechanism. Further, through analysis of additional cases, the role of the upper and lower horizontal legs of the shear reinforcement, the effect of end anchorages on rod-shaped reinforcements were clarified.

Slovak Journal of Civil Engineering

A detailed analysis of concrete structures requires knowledge of the mechanical properties of the materials used. In the case of a non-linear analysis, the scope of the information needed is even greater. In particular, the tensile strength and fracture-mechanical parameters are required for the concrete. Prospective approaches that could increase the informative value of detailed analyses include the use of stochastic modelling. It particularly enables the definition of the effects of individual input parameters on the load capacity, failure mode, and general behaviour of the structure. The presented paper aims at a detailed analysis of a reinforced-concrete beam without shear reinforcement, which is based on a complex set of laboratory tests and non-linear analyses with a sensitivity study. The laboratory program includes different types of laboratory tests. Selected and missing material parameters of the concrete are calculated according to recommendations in scientific papers an...

Ain Shams University Structural Engineering Journal, Cairo, Egypt., 2007

The premature failure problem of beams strengthened with external plates reduces its efficiency. Although this problem is considered in different experimental and analytical studies, more effort is required to increase the efficiency of such expensive strengthening technique. As part of a comprehensive program, this experimental study i s applied on eleven continuous reinforced concrete (R .C ) beams and nine full -scale simply supported R.C beams. The effect of using different materials and schemes for external reinforcing was investigated on the overall behavior of the strengthened beams. Behavior of beams strengthened with the proposed schemes was explored considering its practicality and cost of strengthening. The ultimate load of the tested beams were compared with the design load calculated using the ACI 440-02 guidelines for external flexure and shear strengthening of beams. Generally, controlling the shear cracks propagation by using web plates and reducing stress concentration and crack propagation along the strengthening plate delays the premature mode of failure and correspondingly enhances significantly the strengthened beam’s capacity and ductility. Due to their significant effect, different common strengthening schemes need to be considered in any proposed design guidelines for more economic and reliable applications.

International Journal of Advances in Structural and Geotechnical Engineering

This paper presents numerical investigation on the overall structural behavior of reinforced concrete beams provided with different configurations of embedded steel trusses as web reinforcement. Five specimens having the same dimensions as well as the longitudinal reinforcement were modeled using ABAQUS software. One beam was reinforced with traditional vertical web reinforcement, while the remaining beams were provided with different truss' layout. The main studied criteria were the ultimate failure load, the cracking load, the cracking pattern, principle tensile strain vectors on stirrups and the load versus the mid-span deflection curve. The numerical results showed that using embedded steel truss as web reinforcement resulted in increased the ultimate capacity of the beam by range of (4%-8%) compared to that of the control beam reinforced with traditional vertical stirrups.

Materials and Structures, 2008

Some experimental investigations on ductility and prediction of minimum flexural reinforcement in reinforced concrete (RC) beams are reported. The minimum flexural reinforcement was evaluated using optimum ductility in RC beams. Beams of size 100 mm, 200 mm and 400 mm were tested, which were designed with varying percentages of flexural reinforcement i.e. 0.15, 0.30, 0.60 and 1.0. The beams were tested under four-point loading to study the flexural behaviour under uniform bending moment. The experimentally obtained average compressive strength of concrete was 30 MPa. The influence of beam size (depth) on cracking and normalised ultimate flexural strength, ductility and overall average rotation has been studied. The cracking in RC beams is complex phenomenon in small size beams, while the cracking strength decreases as the depth increases beyond 200 mm. The flexural strength of RC beams, from the present study, appears to decrease as the depth increases. The ductility of RC beams increases as the percentage of flexural reinforcement increases. The ductility number has been derived from dimensional analysis using fracture mechanics principles. The ductility of RC beams decreases as the depth of beams increases. An optimum percentage of flexural reinforcement has been established using optimum ductility number, N p , which is equal to 0.20. The minimum flexural reinforcement was found to decrease as the beam depth increases, and decreases as the yield strength of reinforcement increases.

Engineering Structures, 2014

In this paper, the results from an experimental programme, aimed at investigating moment redistribution in statically indeterminate reinforced concrete structures, are presented and compared with theoretical analysis of the structural behaviour. Due to the nonlinear structural behaviour of reinforced concrete structures, linear elastic analysis can lead to an inaccurate assessment of the behaviour and, therefore, it can become necessary to use more advanced methodologies to achieve sufficiently accurate analysis. Furthermore, more advanced methods can enable a higher degree of performance optimisation of structures than those resulting from the simplified approaches adopted by existing design codes based on linear elastic analysis with redistribution of internal forces. In order to assess the load-carrying capacity at the ultimate limit state (ULS), a model combining plastic and nonlinear analysis is presented. The evolution of moment redistribution to structural collapse was studied experimentally for continuous two-span beams. The focus of the experiments was on the influence of the longitudinal tensile reinforcement ratio at the intermediate support, the transverse reinforcement ratio and the concrete strength. The experimental response at the ULS was further compared with the predicted distribution of internal forces according to the theoretical model. Evaluation of the experimental study indicated a highly nonlinear structural behaviour of the tested beams with the distribution of moment differing from linear elastic analysis, even for low load levels. The evolution of moment redistribution and the moment redistribution at the ULS were appreciably dependent on the arrangement of longitudinal reinforcement, whilst the transverse reinforcement ratio had a marginal impact up to yielding of the longitudinal reinforcing steel, with the concrete strength slightly reducing the degree of moment redistribution. For those beams which failed in flexure, predictions from the theoretical model presented were in good agreement with the experimental results. However, several beams collapsed in shear-related failure modes.

ISET INTERNATIONAL CONFERENCE ON APPLIED SCIENCE & ENGINEERING (CASE 2021)

A detailed survey was made on the different cement proportions and concrete grades used for the structural elements. The various strengthening methods studies in concrete were done by researchers in different part of the world. Strengthening increase the ultimate load carrying capacity this approach is relatively simple to implement and result in reduction in retrofitting cost compared to other for a structure or a bridge with identical beam diameters, there are practical and dependable techniques. The primary goal of these experiments is to learn more about the behaviour of RCC beams that have been strengthened using RC plates. All material testing were carried out in the laboratory in accordance with the Indian Standard regulations. Fine aggregate, coarse aggregate, and cement were subjected to basic tests to determine their suitability for concrete production. The concrete mix was created according to IS 10262:1982 for M20 concrete grade.

University of Tehran, 2018

The current approach for designing reinforced concrete members is based on the load and resistance factor. However the load and resistance parameters are random variables, the constant values have been designated for them in the designing procedure. Assuming these factors as the constants will be led to unsafe and uneconomical designs. Safe designing of structures requires appropriate recognition of the effective parameters and their uncertainties. Therefore, this achievement is possible through clarifying the effective design parameters and applying risk-based design methods. The main purpose of this paper is the reliability-based design of the reinforcement concrete structures under bending action. Rectangular sections with tension rebars (singly reinforced), rectangular sections with tension and also compression rebars (doubly reinforced) and T-shape sections are designed based on probabilistic methods. The appropriate tool for reliability calculations is selected based on the pros and cons of each method. Evaluation of the load and the resistance factors for all mentioned beams is the next goal of this investigation. In this research, the steel usages for the desired safety level are determined through the produced graphs. Using the proposed methodologies, the economic and fully probabilistic design of the concrete beams for bending is now available.

IOP Conference Series: Earth and Environmental Science, 2020

Massive exploration of the natural materials for producing concretes affect to the environment condition and global warming that may cause natural disasters. Therefore the using of the concrete materials should be as efficient as possible. According to its natural behavior of the concrete material, it is strong in compression and weak in tension. Therefore the contribution of the tensile stresses of the concrete to the flexural capacity of the beams is neglected. However, removing concrete on the tension zone affects to the decreasing of flexural capacity. Based on the previous studies, beam without concrete at the tension zone using truss-system reinforcement causes the tension crack near the supports. This crack might because decreasing the flexural capacity of the beam. One of the solutions to solve this problem is by strengthening the beams using steel reinforcements. Therefore, this study aims to investigate the effect of steel reinforcement near the supports on the behavior of...

Strength of Materials, 2014

Îäíèì èç ýêîíîìè÷åñêè ýôôåêòèâíûõ è ïðîñòûõ ñïîñîáîâ ïîâûøåíèÿ ïðî÷íîñòè ïðè èçãèáå ÿâëÿåòñÿ óêðåïëåíèå áàëêè ñ ïîìîùüþ íàðóaeíûõ ñòåðaeíåé íà óðîâíå åå íèaeíåé ïîâåðõíîñòè. Îáñóaeäàþòñÿ ìîäåëèðîâàíèå ìåòîäîì êîíå÷íûõ ýëåìåíòîâ è íåëèíåéíûé àíàëèç aeåëåçîáåòîííûõ áàëîê ñ äîïîëíèòåëüíûìè àðìàòóðíûìè ñòåðaeíÿìè, âûïîëíåííûå íà áàçå ïðîãðàììíîãî êîìïëåêñà ANSYS 12.0. Ìîäåëèðîâàíèå ìåòîäîì êîíå÷íûõ ýëåìåíòîâ aeåëåçîáåòîííûõ áàëîê ïðîâîäèëîñü íà îñíîâå äèñêðåòíîãî ìîäåëèðîâàíèÿ àðìèðîâàíèÿ. Ïîëó÷åííûå äàííûå ñðàâíèâàëèñü ñ ðåçóëüòàòàìè ýêñïåðèìåíòàëüíûõ èññëåäîâàíèé 20 îáðàçöîâ áàëêè ïðè ÷åòûðåõòî÷å÷íîì èçãèáå. Äëÿ ìîäåëèðîâàíèÿ áàëêè ìåòîäîì êîíå÷íûõ ýëåìåíòîâ èñïîëüçîâàëèñü ýëåìåíòû SOLID65, SOLID45 è LINK8. Íàëè÷èå óïðóãèõ ýëåìåíòîâ COMBIN39 ïîçâîëèëî ñìîäåëèðîâàòü êîíòàêò òðåíèÿ ìåaeäó íèaeíåé ïîâåðõíîñòüþ áàëêè è íàðóaeíûìè ñòåðaeíÿìè. Ðåçóëüòàòû èññëåäîâàíèé èçîãíóòîé ôîðìû áàëêè, èçìåíåíèÿ äåôîðìàöèè ïî åå äëèíå è ãëóáèíå, à òàêaeå ðàñïðîñòðàíåíèå òðåùèíû íà ðàçíûõ ñòàäèÿõ íàãðóaeåíèÿ ïðåäñòàâëåíû â âèäå øèðîêîäèàïàçîííîãî ãðàôè÷åñêîãî äèñïëåÿ ñ ïîìîùüþ êîìàíäíîãî ôàéëà ñ èñïîëüçîâàíèåì êîìïëåêñà ïàðàìåòðè÷åñêîãî ïðîåêòèðîâàíèÿ ANSYS. Êëþ÷åâûå ñëîâà: íàðóaeíûå ñòåðaeíè, ïðîãðàììíûé êîìïëåêñ ANSYS, ýëåìåíò COMBIN39. Introduction. Strengthening of existing reinforced concrete (RC) structures is of prime importance in the current scenario due to the reasons such as to safeguard the non-engineered buildings, and upgrade the vulnerable buildings to current seismic codes, Retrofitting of existing buildings is always preferred over demolition and reconstruction so as to reduce the consumption of raw materials and mitigate the global warming problems. The existing strengthening methods, such as section enlargement, bonded steel plating, external post-tensioning and fiber reinforced polymer (FRP) composites wrapping, have demerits, such as high cost, loss of aesthetics, increase in self-weight, need for careful surface preparation, unexpected delamination failure, etc. The external reinforcement technique proposed by the authors [1] has advantages such as speed and simplicity of installation; minimal disruption during installation; use of cost effective materials; greater cross-sectional area of external bars when compared to prestressed tendons makes it less susceptible to corrosion, vandalism and sabotage; minimal surface preparation of concrete substrate; no delamination failure problems, as experienced in bonded plates and FRP laminates [2, 3]. In this paper, results of the nonlinear finite element (FE) analysis of twenty

Zenodo (CERN European Organization for Nuclear Research), 2019

Numerical investigation on a reinforced concrete (RC) frame structure is carried out to attain a ductile failure of structure by providing an effective detailing of reinforcement. Structure is made to undergo ductile failure by inducing plastic hinge in the beams instead of beam column junctions. A two dimensional G+9 floors frame with 4 bays is analyzed using STAAD.Pro for all kinds of load combinations, which includes earthquake and wind loads. The beam having maximum bending moment is considered and the reinforcement arrangement is done in such a way that the hinges are formed in the beams instead of beam column junctions which cause the structure to fail locally and not globally.