Analysis of Dowel Action in Reinforced Concrete Beams with Shear Reinforcement

Abstract The shear transfer mechanism was examined to view the contributions of different components of shear transfer such as aggregate interlocking, dowel force and uncracked compression zone. Understanding the role of various shear transfer components with transverse reinforcement provided was complex due to traditional difficulties involved in detail assessment of accompanying kinematics during the failure. In the present paper, the issue was addressed by employing sixteen specimens and grouped under two categories representing conventional beams and beams with preformed cracks and were tested under four - point bending load with a shear span to depth ratio of 1.26 by increasing the characteristic strength of concrete. From the results obtained, empirical formulas proposed were also evaluated and it was concluded that the results were consistent and contribution of shear transfer across uncracked compression zone was maximum in shear resistance with transverse reinforcement provided. Later structural behaviour was also assessed and it was concluded that beams with preformed cracks had exhibited greater stiffness thus nullifying the effect of aggregate interlocking in shear transfer.

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Mechanism of shear transfer in reinforced concrete beams

Canadian Journal of Civil Engineering ◽

10.1139/l77-019 ◽

1977 ◽

Vol 4 (2) ◽

pp. 145-152

Author(s):

K. N. Smith ◽

S. M. Fereig

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Measurement Data ◽

Reinforced Concrete Beams ◽

Compression Zone ◽

Interface Shear ◽

Small Component ◽

Shear Transfer ◽

Dowel Action ◽

Web Reinforcement

The mechanism of shear transfer in reinforced concrete beams with short shear spans is investigated with a view to defining the relative contribution of various component actions such as interface shear transfer across the characteristic inclined crack in such members, shear transferred by the uncracked compression zone, dowel action by the longitudinal tension reinforcement, and the contribution of the web reinforcement. The members tested and analyzed have a shear span to depth ratio of 1.5 and were loaded in the common framing situation involving shear on the sides of the members.For the beams either with horizontal web reinforcement or without any web reinforcement the distribution of internal forces was similar, with interface shear transfer, dowel action, and shear carried by the compression zone contributing to the capacity. In the case of members for which vertical web reinforcement was provided, interface shear transfer and dowel action were decreased to comparatively small component actions in the system. Acquisition of extensive measurement data and analysis of the behaviour history through various stages of loading permit the mechanism of shear transfer to be quantitatively defined.

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Experimental Evaluation on Components of Shear resistance of Reinforced Concrete Beams with Shear Reinforcement Provided

10.21203/rs.3.rs-579222/v1 ◽

2021 ◽

Author(s):

Sreenivasa Prasad Joshi ◽

Poluraju P

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Shear Resistance ◽

Transfer Mechanism ◽

Reinforced Concrete Beams ◽

Structural Behavior ◽

Compression Zone ◽

Shear Reinforcement ◽

Shear Transfer ◽

Aggregate Interlocking

Abstract The contribution of aggregate interlocking and dowel force in shear strength of reinforced concrete beams was topic of research for many years. The precise forecasts of shear behavior were challenging to determine due to complication involved. The existing theories had focused on aggregate interlocking force and shear resistance arising due to concrete compression zone, neglecting the contribution of dowel force despite considering as significant constituent in shear transfer mechanism. The present investigation focuses on cogitating all components in shear transfer mechanism by providing shear reinforcement and keeping clear cover and effective span to depth ratio constant. Sixteen specimens were considered for parametric study by employing suitable variables such as increase in strength of concrete and variation in flexural reinforcement. Eight specimens were conventional beams and the remaining eight specimens were provided with preformed cracks. Moment vs. displacement curvature and strain vs. moment curvature were plotted to evaluate shear at uncracked compression zone and accordingly aggregate interlocking force and dowel force were determined based on the empirical formulas proposed. From the result it was confirmed that contribution of aggregate interlocking force and dowel force were insignificant and shear resistance due to uncracked compression zone is the sole contributor in shear transfer mechanism. Structural behavior of concrete beams was also studied and it was confirmed that beams with preformed cracks exhibited better structural behavior when related to conventional beams.

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Repair of Heavily Damaged RC Beams Failing in Shear Using U-Shaped Mortar Jackets

Buildings ◽

10.3390/buildings9060146 ◽

2019 ◽

Vol 9 (6) ◽

pp. 146 ◽

Cited By ~ 8

Author(s):

Constantin Chalioris ◽

Violetta Kytinou ◽

Maristella Voutetaki ◽

Nikos Papadopoulos

Keyword(s):

Structural Reliability ◽

Concrete Beams ◽

Small Diameter ◽

Reinforced Concrete Beams ◽

Repair System ◽

Reinforcing Bars ◽

Four Point Bending ◽

Relative Shear ◽

Bending Load ◽

Strength And Deformation

The effectiveness of slightly reinforced thin U-shaped cementitious mortar jacketing for the repair of damaged shear-critical reinforced concrete beams is experimentally investigated. The test project includes two parts. In the first one, five concrete beams over-reinforced against flexure and under-reinforced against shear with different ratio of closed stirrups were initially subjected to monotonic loading until failure. The initially tested beams have been designed to fail in shear after wide diagonal cracking and to exhibit various strength and deformation capacities along with different levels of damages. In the second experimental part, the heavily damaged beams were jacketed with mild steel small diameter U-shaped transverse stirrups and longitudinal reinforcing bars. The retrofitted specimens using the proposed jacketing technique were tested again following the same four-point-bending load scheme. Based on the overall performance of the beams, it is deduced that the shear strength and deformation capability of the jacketed beams were substantially increased compared to the corresponding capacities of the initial beams. Further, although all beams failed in a shear abrupt manner, the retrofitted ones exhibited reduced brittleness and higher deflections at failure up to six times with respect to the initially tested specimens. The level of the initial damage influences the efficiency of the jacketing. Additional test data derived from relative shear-damaged beam specimens and retrofitted with similar thin jackets is also presented herein in order to establish the effectiveness of this repair system and to clarify the parameters affecting its structural reliability. Comparisons indicated that jacketed beams can alter the failure mode from brittle shear to ductile flexural under certain circumstances.

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Structural behaviour of PSCC slab panel under four-point bending test

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1144/1/012039 ◽

2021 ◽

Vol 1144 (1) ◽

pp. 012039

Author(s):

M A Iman ◽

N Mohamad ◽

A A A Samad ◽

Steafenie George ◽

M A Tambichik ◽

...

Keyword(s):

Bending Test ◽

Structural Behaviour ◽

Four Point Bending ◽

Four Point Bending Test

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The influence of infill density gradient on the mechanical properties of PLA optimized structures by additive manufacturing

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/14644207211007159 ◽

2021 ◽

pp. 146442072110071

Author(s):

AIL Pais ◽

C Silva ◽

MC Marques ◽

JL Alves ◽

J Belinha

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Additive Manufacturing ◽

Structural Optimization ◽

Meshless Method ◽

Load Case ◽

Fused Filament Fabrication ◽

Ductile Metals ◽

Four Point Bending ◽

Bending Load

The aim of this work is the development of a novel framework for structural optimization using bio-inspired remodelling algorithm adapted to additive manufacturing. The fact that polylactic acid (PLA, E = 3145 MPa (Young’s modulus) according to the supplier for parts obtained by injection) shows a similar parameterized behavior with ductile metals, in the sense that both materials are characterized by a bi-linear elastic-plastic law, allows to simulate and prototype parts to be further constructed in ductile metals at a lower cost and then be produced with more expensive fabrication processes. Moreover, cellular materials allow for a significant weight reduction and therefore reduction of production costs. Structural optimization algorithms based on biological phenomena were used to determine the density distribution of the infill density of the specimens. Several simple structures were submitted to distinct complex load cases and analyzed using the mentioned optimization algorithms combined with the finite element method and a meshless method. The surface was divided according to similar density and then converted to stereolitography files and infilled with the gyroid structure at the desired density determined before, using open-source slicing software. Smoothing functions were used to smooth the density field obtained with the remodeling algorithms. The samples were printed with fused filament fabrication technology and submitted to mechanical flexural tests similar to the ones analyzed analytically, namely three- and four-point bending tests. Thus, the factors of analysis were the smoothing parameter and the remodeling method, and the responses evaluated were stiffness, specific stiffness, maximum force, and mass. The experimental results correlated (obtaining accuracy of 35% for the three-point bending load case and 5% for the four-point bending load case) to the numerical results in terms of flexural stiffness and it was found that the complexity of the load case is relevant for the efficiency of the functional gradient. The fused filament fabrication process is still not accurate enough to be able to experimentally compare the results based of finite element method and meshless method analyses.

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