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Frontiers of Structural and Civil Engineering

Front. Struct. Civ. Eng.    2014, Vol. 8 Issue (4) : 325-336     https://doi.org/10.1007/s11709-014-0080-1
RESEARCH ARTICLE |
Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement
Dong XU(),Yu ZHAO,Chao LIU
Department of Bridge Engineering, Tongji University, Shanghai 200092, China
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Abstract

In determining the shear capacity of reinforced concrete beams, current codes do not provide any calculation method to evaluate the influence of web horizontal reinforcement, although they exist as structural reinforcements (or skin reinforcement). The present paper comprises results of 11 reinforced concrete beams in an effort to investigate the influence of web horizontal reinforcement on the shear behavior of reinforced concrete beams. The primary design variables are the shear-span-depth ratio, different reinforcement ratio of stirrups and web horizontal reinforcement. Influence of web horizontal reinforcement on crack patterns and failure mode was studied. It was found that web horizontal reinforcement can increase the shear capacity of the beams and restrain growth of inclined cracks effectively. Test results are very valuable, as very few references of shear tests can be found focusing on the effect of web horizontal reinforcement on the shear capacity of the beams.

Keywords reinforced concrete beam      shear strength      web horizontal reinforcement      experiments     
Corresponding Authors: Dong XU   
Online First Date: 12 December 2014    Issue Date: 12 January 2015
 Cite this article:   
Dong XU,Yu ZHAO,Chao LIU. Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement[J]. Front. Struct. Civ. Eng., 2014, 8(4): 325-336.
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http://journal.hep.com.cn/fsce/EN/10.1007/s11709-014-0080-1
http://journal.hep.com.cn/fsce/EN/Y2014/V8/I4/325
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Dong XU
Yu ZHAO
Chao LIU
beam fc(MPa) bw(mm) h(mm) d(mm) sk(mm) a(mm) a/d ?l(%) ?t(%) web horizontal reinforcement ?h(%) Vexp(kN)
R40-1 42.1 200.0 400.0 350.0 80.0 690.0 2.0 3.6 0.63 ?8@80 0.63 325.0
R40-2 42.1 200.0 400.0 350.0 80.0 860.0 2.5 3.6 0.63 ?8@80 0.63 240.0
R40-3 42.1 200.0 400.0 350.0 80.0 860.0 2.5 3.6 0.63 ?8@80 0.63 245.0
R40-4 42.1 200.0 400.0 350.0 80.0 1050.0 3.0 3.6 0.63 ?8@80 0.63 -b
R25-1 32.3 120.0 320.0 290.0 80.0 600.0 2.0 3.5 0.59 ?6@60 0.78 150.0
R25-2 32.3 120.0 320.0 290.0 80.0 600.0 2.0 3.5 0.59 ?6@60 0.78 150.0
R25-3 32.3 120.0 320.0 290.0 80.0 600.0 2.0 3.5 0.59 -a 0.0 145.0
R25-4 32.3 120.0 320.0 290.0 80.0 600.0 2.0 3.5 0.59 -a 0.0 145.0
T40-1 43.2 70.0 360.0 330.0 80.0 660.0 2.0 1.4 0.34 -a 0.0 62.5
T40-2 43.2 70.0 360.0 330.0 80.0 660.0 2.0 1.4 0.34 ?3.5@80 0.34 87.5
T40-3 43.2 70.0 360.0 330.0 55.0 660.0 2.0 1.4 0.50 -a 0.0 80.0
Tab.1  Details of the beam specimens
Fig.1  Elevation and cross section of beam specimens in series R40 (unit: mm)
Fig.2  Elevation and cross section of beam specimens in series R25. (a) R25-1/2; (b) R25-3/4 (unit: mm)
Fig.3  Elevation and cross section of beam specimens in series T40. (a) T40-1; (b) T40-2; (c) T40-3 (unit: mm)
C40 C25
cement (kg/m3) 480.0 (CEM I/42.5 R) 338.0 (CEM I/32.5 R)
sand (kg/m3) 576.0 676.0
aggregate 5/20(kg/m3) 1152.0 1217.0
water (kg/m3) 192.0 169.0
w/c ratio 0.33 0.25
Ec(MPa) 3.50E+ 04 3.50E+ 04
Tab.2  Concrete composition and elasticity modulus
size area(mm2) fy(MPa) fu(MPa)
?3.5 9.62 335.0 410.0
?6 28.27 242.0 330.0
?8 50.27 234.0 325.0
?16 201.10 363.0 567.0
?20 314.20 363.0 567.0
Tab.3  Properties of reinforcing bars
Fig.4  Instrumentations in test beams. (a) strain gauges attached to steel reinforcements; (b) strain gauges attached to concrete and LVDTs
Fig.5  Test layout
Fig.6  Crack patterns in test series R40. (a) R40-1; (b) R40-2; (c) R40-3; (d) R40-4
Fig.7  Crack patterns in test series R25. (a) R25-1; (b) R25-2; (c) R25-3; (d) R25-4
Fig.8  Crack patterns in test series T40. (a) T40-1; (b) T40-2; (c) ; (d) T40-3
Fig.9  Strain results of test beam R40-1. (a) strain gauges attached to horizontal reinforcement; (b) strain value
Fig.10  Strain results of test beams in Series T40. (a) strain gauge distribution in longitudinal flexural reinforcement; (b) relation between strain in longitudinal flexural reinforcement and applied load: Beam T40-1 only with stirrups; Beam T40-2 with grid reinforcement
equations comments
EC 2 2004 beams without web reinforcement V R d c = [ 0.18 k ( 100 ρ l f c k ) 1 / 3 + 0.15 σ c p ] b w d V R d c m i n = ( 0.035 k 3 / 2 f c k 1 / 2 + σ c p ) b w d Beans with web reinforcement (VRd,c = 0) V R d , s = A s v f y v s 0.9 d cot ? θ k = 1 + 200 d 2.0 ρ l = A s l b w d 0.02 1 cot ? θ 2.5
AASHTO LRFD 2004 Vc=0.083βfcbw?0.9dVs=Asvfyvs0.9dVmax?=0.25fcbw?0.9d ? and ? listed in a table as a function of the longitudinal strain in the web and the non-dimensional shear.
ACI 318-05 Vc=(0.16fc+17ρlVdM)bwd0.29fcbwdVs=Asvfyvsd0.66fcbwd fc8.3MPaVdM1
Tab.4  Summary of different shear procedures
beam Vexp(kN) Vcal(kN) Vexp /Vcal
ACI AASHTO EC2 ACI AASHTO EC2
cot? = 1 cot? = 2.5 cot? = 1 cot? = 2.5
R40-1 325.0 192.0 260.0 92.6 231.0 1.69 1.25 3.51 1.40
R40-2 240.0 188.0 241.0 92.6 231.0 1.28 1.00 2.59 1.04
R40-3 245.0 188.0 241.0 92.6 231.0 1.30 1.02 2.65 1.06
R25-1 150.0 93.0 117.0 44.6 112.0 1.61 1.28 3.36 1.34
R25-2 150.0 93.0 117.0 44.6 112.0 1.61 1.28 3.36 1.34
R25-3 145.0 93.0 114.0 44.6 112.0 1.56 1.27 3.25 1.30
R25-4 145.0 93.0 114.0 44.6 112.0 1.56 1.27 3.25 1.30
T40-1 62.5 52.0 41.0 23.9 60.0 1.20 1.51 2.61 1.04
T40-2 87.5 52.0 49.0 23.9 60.0 1.68 1.79 3.66 1.46
T40-3 80.0 64.0 44.0 34.8 87.0 1.25 1.84 2.30 0.92
Average 1.47 1.35 3.05 1.22
Standarddeviation 0.19 0.28 0.47 0.19
COV 0.13 0.21 0.15 0.15
Tab.5  Comparisons between experimental results and theoretical predictions from different design procedures
a = shear span
As = area of bottom longitudial flexural reinforcement
Ash = area of horizontal shear reinforcement
Asv = area of transverse shear reinforcement or stirrup
bw = web width of concrete beam
d = distance from the extreme compression fiber to the centroid of longitudinal tension reinforcement
fc = cubic compression strength of concrete
fc = cylindrical compression strength of concrete
fs = stress in reinforcement
fsh = stress in horizontal shear reinforcement
fsl = stress in bottom longitudinal reinforcement
fsv = stress in transverse shear reinforcement or stirrup
ft = unaxial tensile strength of concrete
fu = ultimate strength of reinforcement
fy = yield strength of reinforcement
fyh = yield strength of horizontal shear reinforcement
fyv = yield strength of transverse shear reinforcement or stirrup
h = depth of beam
M = applied bending moment
N = applied axial force
sh = spacing of horizontal shear reinforcement
sk = spacing of transverse shear reinforcement or stirrup
V = applied shear force
Vc = contribution of concrete to shear strength
Vcal = calculated shear strength
Vexp = experimentallly observed shear strength
θ = inclination of concrete strut
ρh = ratio of horizontal shear reinforcement, ρh = Ash/bwsh
ρ1 = ratio of bottom longitudinal flexural reinforcement, ρt = As/bwd
ρt = ratio of transverse shear reinforcement, ρt = Asv/bwsk
Tab.6  Notations
1 Joint ACI-ASCE Committee 445. Recent approaches to shear design of structural concrete. Journal of Structural Engineering, 1998, 124(12): 1375-1417
2 ACI Committee 318. Building Code requirements for Structural Concrete (ACI 318-05) and Commentary (318R-05). American Concrete Institute, Farmington Hills, Mich, 2005
3 European Committee for StandardizationUNE-ENV 1992-1-1:2004 Eurocode 2. Deisgn of concrete structures. Part 1-1: General Rules and Rules for Buildings. Brussels, 2004
4 Collins M P, Mitchell D. Prestressed concrete Structures. Prentice Hall, Englewood Cliffs, N J, 1991
5 Committee C S A. A23.3. Design of concrete structures (CSA A23.3-04). Canadian Standards Association, Mississauga, 2004
6 AASHTO LRFD. Bridge Design Specification and Commentary, 3rd Edition, American Association of State Highway and Transportation Officials, Washington D C, 2004
7 Choi K K, Sherif A G, Reda-Taha M M, Chung L. Shear Strength of Slender Reinforced Concrete Beams without Web Reinforcement: A Model using Fuzzy Set Theory. Engineering Structures, 2009, 31(3): 768-777
8 Jung S, Kim K S. Knowledge-based prediction of shear strength of concrete beams without shear reinforcement. Engineering Structures, 2008, 30(6): 1515-1525
9 Reineck K H, Kuchma D A, Kim K S, Marx S. Shear database for reinforced concrete members without shear reinforcement. ACI Structural Journal, 2003, 100(2): 240-249
10 El-Chabib H, Nehdi M, Said A. Predicting shear capacity of NSC and HSC slender beams without stirrups using artificial intelligence. Computers and Concrete, 2005, 2(1): 79-96
11 Cladera A, Mari A R. Experimental Study on High-strength Concrete Beams Failing in Shear. Engineering Structures, 2005, 27(10): 1519-1527
12 Teoh B K, Mansur M A, Wee T H. Behaviour of high-strength concrete I-beams with low shear reinforcement. ACI Structural Journal, 2002, 99(3): 299-307
13 Fournier B, Razaqpur A G, Abbas A, Fathifazl G, Foo S, Isgor O B. Shear Strength of Reinforced Recycled Concrete Beams with Stirrups. Magazine of Concrete Research, 2010, 62(10): 685-699
14 Ritter W. Die Bauweise Hennebique. Switzerland: Schweizerische Bauzeitung, Switzerland1899
15 M?rsch E. Concrete-Steel Construction (Der Eisenbetonbau). English translation of the 3rd German edition, McGraw-Hill Book Co., New work. 1909.
16 JTG D62-2004 Code for Design Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts. Beijing: China Communications Press, Beijing, 2004 (in Chinese)
17 Bentz E C. Sectional analysis of reinforced concrete members. Dissertation for the Doctoral Degree. Toronto: University of Toronto, 2000
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