scholarly journals Comparative study of theoretical and real deflection of a simple and reinforced concret joist

2021 ◽  
Vol 41 (2) ◽  
pp. e86742
Author(s):  
Sócrates Pedro Muñoz ◽  
Angel Antonio Ruiz Pico ◽  
Juan Manuel Anton Perez ◽  
Dandy B. Roca-Loayza
Keyword(s):  
Reinforced Concrete ◽  
Theoretical Model ◽  
Comparative Study ◽  
Elastic Element ◽  
Integration Method ◽  
Mix Design ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Maximum Deflection ◽  
Double Integration

This research aims to determine the actual deflection of a concrete joist and to correlate the result with the theoretical deflection. This is based on the theories of elasticity as the double integration method, considering the homogeneous, isotropic and linearly elastic material from an ideal theoretical model. The construction of a concrete joist does not make a 100% homogeneous, isotropic and linearly elastic element, since its manufacture depends on many conditions such as the choice of aggregates, water, the manufacture of cement, tests carried out for the elaboration of the mix design, the operator who is going to perform the mix and the construction of the joist. The variation of the real deflection with respect to the theoretical one has been investigated. For this, 30 simple concrete joists and 30 reinforced concrete joists were manufactured. The dimensions of these joists were 15cm x15cmx53.5cm (b x h x L). The reinforcement of the last 30 joists was 4 Փ 1/4 "as longitudinal reinforcement and Փ 1/4" @ 0.10 m of transverse reinforcement. The joists were tested for flexion by measuring the maximum deflection and compared with the theoretical one, calculated by the double integration method, having much greater experimental results than those calculated with the theory of the double integration method, not being within the ranges expected in literature

scholarly journals Experimental analysis of the concrete contribution to shear strength beams without shear reinforcement

2017 ◽  
Vol 10 (1) ◽  
pp. 160-172
Author(s):  
M. S. Samora ◽  
A. C. DOS Santos ◽  
L. M. Trautwein ◽  
M. G. Marques
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Resistance Mechanisms ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Reinforced Concrete Structure ◽  
Empirical Formulas ◽  
Limit States ◽  
Domain 3

Abstract There are many theories and empirical formulas for estimating the shear strength of reinforced concrete structures without transverse reinforcement. The security factor of any reinforced concrete structure, against a possible collapse, is that it does not depend on the tensile strength of the concrete and the formation of any collapse is ductile, thus giving advance warning. The cracking from tensile stress can cause breakage of the concrete and should be avoided at all cost, with the intent that any such breakage does not incur any type of failure within the structure. In the present research study, experiments were performed in order to analyze the complementary mechanisms of the shear strength of lattice beams of reinforced concrete frames without transverse reinforcement. The experimental program entails the testing of eight frames that were subjected to a simple bending process. Two concrete resistance classes for analyzing compressive strength were considered on the construction of frames, 20 MPa and 40 MPa. To resist the bending stresses, the beams of the frames are designed in domain 3 of the ultimate limit states. Different rates and diameters of longitudinal reinforcement were used, 1.32% and 1.55% with 12.5 mm diameter and 16.0 mm in longitudinal tensile reinforcement. From the obtained results, an analysis was made of the criteria already proposed for defining the norms pertinent to the portion of relevant contribution for the shear resistance mechanisms of concrete without the use of transverse reinforcement and the influence of the concrete resistance and longitudinal reinforcement rates established in the experimental numerical results.

scholarly journals The SHEAR BEHAVIOR OF REINFORCED CONCRETE BEAMS STRENGTHENED BY CFRP STRIPS

2021 ◽  
pp. 1-9
Author(s):  
Lubna Mohammed Abd
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Maximum Deflection ◽  
Modes Of Failure ◽  
Different Shapes ◽  
Combined Failure

   In this research, (12) normal reinforced concrete beams are used with dimensions (110*10*20) cm, the compressive strength for all specimens is 30 MPa. Longitudinal steel is deformed bars 2Ø12mm with Ø6 mm transverse reinforcement which is deformed bars also for different spacing 5 cm, 10 cm and 15 cm. After casting  the specimens and removing them from the molds, they left for about 28 days. They tied by CFRP strips  with different shapes of tying (tied, inclined and X- shaped). They are all testing with two points load by a hydraulic machine for determining (Pu, P cr, maximum deflection and modes of failure) and compared among  their results with the specimens without CFRP strips. From the experimental program, the excellent behavior of the specimens with the X-shaped strips especially with the Pu which is 70% increment and maximum deflection is 39%  decrement. The addition of CFRP strips as a tying material helps to increase the strength of concrete and bearing against loads also, changes and decreases the flexural and shear failure and combined failure.

scholarly journals Investigation of longitudinal reinforcement contribution in shear punching of reinforced concrete flat slabs without transverse reinforcement

2019 ◽  
Vol 279 ◽  
pp. 02005
Author(s):  
Vladimir Alekhin ◽  
Alexander Budarin ◽  
Maxim Pletnev ◽  
Liubov Avdonina
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Load Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Factors Affecting ◽  
Codes Of Practice ◽  
Reinforced Concrete Slabs

The shear punching of the reinforced concrete slabs is a complex process occurring when considerable force is concentrated on the relatively small area of a column-slab connection. An incorrect assessment of load capacity of slab under the punching shear may lead to an accident. One of the most significant factors affecting the slab capacity is longitudinal reinforcement. In this article much attention is given to the analysis of the longitudinal rebar impact on the maximum loading capacity of reinforced concrete slabs without transverse reinforcement affected by punching shear force using the finite element method. The results obtained via the finite element simulation are compared with laboratory tests and manual calculations carried-out using various methods represented in different national building Codes of practice.

scholarly journals Confinement Effect of Reinforced Concrete Columns with Rectangular and Octagon-Shaped Spirals

2020 ◽  
Vol 12 (19) ◽  
pp. 7981
Author(s):  
Hyeong-Gook Kim ◽  
Chan-Yu Jeong ◽  
Dong-Hwan Kim ◽  
Kil-Hee Kim
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Rc Columns ◽  
Rc Column ◽  
Cyclic Lateral Load ◽  
Ductility Capacity ◽  
Constant Axial Load ◽  
Spiral Type

Conventional spiral-type transverse reinforcement is effective at increasing the ductility and the maximum strength of reinforced concrete (RC) columns because it confines the inner concrete and the longitudinal reinforcement. However, when arranging crossties in a RC column with spirals, problems such as mutual interference with longitudinal reinforcement, overcrowding of reinforcement, and deterioration of constructability occur. Furthermore, the loosening of 90 and 130-degree standard hooks due to the lateral expansion of concrete causes buckling of the longitudinal reinforcement. This paper describes the ability of a newly developed spiral-type transverse reinforcement with various yield strengths to confine RC columns subjected to cyclic lateral load and constant axial load. The ductility capacity, energy dissipation, and effective stiffness of RC columns confined by the developed spiral-type transverse reinforcement were compared with those of RC columns confined by typical rectangular reinforcement. The experimental results showed that RC column specimens with the developed spiral-type transverse reinforcement have better performances in terms of ductility capacity and energy dissipation, even though the amount of reinforcement used for the specimens decreased by about 27% compared with the specimen with typical rectangular reinforcement.

scholarly journals Analytical Estimation of the Residual Drift of Reinforced Concrete Columns under the Ultimate Displacement Capacity

2020 ◽  
Author(s):  
Sinan Cansız
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Load Level ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Reinforced Concrete Columns ◽  
Residual Drift ◽  
Drift Ratio ◽  
Ultimate Displacement

Reinforced concrete columns are the most important structural elements that determine the ductility of the structures. The main parameters affecting the behavior of reinforced concrete columns are axial load level, shear span, percent of longitudinal reinforcement and percent of transverse reinforcement. The aim of this study is to examine residual damage behavior of RC columns under cyclic loading similar to the earthquake loads combined depend on variable axial load level, spanning to depth ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. When the results of experiments are examined, it can be seen that the residual drift ratio of reinforced concrete columns can be used to characterize the damage occurred in the structure after earthquake or loading. In addition, the performance level of the reinforced concrete columns according to the residual drift ratio is defined in FEMA356. As a result of this study, the analytical equation that calculates the residual drift ratio of the reinforced concrete columns at the ultimate displacement limit is proposed.

Improvement Of The Method For Calculation Of Reinforced Concrete Bending Elements By Inclined Sections

2019 ◽  
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Transverse Reinforcement ◽  
Theoretical Studies ◽  
Longitudinal Reinforcement ◽  
Inclined Crack ◽  
Major Factors ◽  
Concrete Elements ◽  
Experimental And Theoretical Studies ◽  
Detailed Picture

Testing of a large number of bending pre-stressed concrete elements and elements without pre-stressing of longitudinal reinforcement with their destruction by inclined sections, as well as analysis of numerous experimental and theoretical studies both domestic and foreign made it possible to obtain a detailed picture of the stress-strain state in concrete and reinforcement in the area of transverse forces action. Values of influence on the bearing capacity of the bending reinforced concrete elements of such factors as cohesion forces of the rough surface of the banks in the inclined crack, the dowel effect of the longitudinal reinforcement at the intersection of its inclined fracture, pre-stress in longitudinal reinforcement, depending on the transverse width of the elements, and in transverse reinforcement, depending on the forces of the elastic compression of concrete by stressed longitudinal reinforcement, etc. are set. According to the research results, it is concluded that it is expedient to improve the method of calculating the strength of bending concrete elements by inclined sections, laid down in the regulations, taking into account the influence of all major factors.

Discrete versus average integration in shear assessment of spiral links

2009 ◽  
Vol 36 (2) ◽  
pp. 171-179 ◽  
Author(s):  
Kamal Jaafar
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Circular Cross Section ◽  
Shear Resistance ◽  
Shear Loading ◽  
Reinforced Concrete Beams ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Concrete Members ◽  
Combined Action

Common transverse reinforcement of reinforced concrete members with circular cross section consists of round ties or spirals. Its purpose in members that are not subjected to significant shear loading is to provide proper confinement for concrete, and eliminate buckling of the longitudinal reinforcement bars. If spirals are to be used as both a shear resister and confining enabler for reinforced concrete beams, then under combined action of moment and shear, spirals will be required to provide or contribute to proper shear resistance. Hence a proper assessment for spiral shear contribution is required.

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