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.

Online First Date: 12 December 2014Issue 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.

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/m^{3})

480.0 (CEM I/42.5 R)

338.0 (CEM I/32.5 R)

sand (kg/m^{3})

576.0

676.0

aggregate 5/20(kg/m^{3})

1152.0

1217.0

water (kg/m^{3})

192.0

169.0

w/c ratio

0.33

0.25

E_{c}(MPa)

3.50E+ 04

3.50E+ 04

Tab.2 Concrete composition and elasticity modulus

size

area(mm^{2})

f_{y(}MPa)

f_{u(}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 VRdc=[0.18k(100ρlfck)1/3+0.15σcp]bwdVRdcmin=(0.035k3/2fck1/2+σcp)bwdBeans with web reinforcement (V_{Rd,c} = 0) VRd,s=Asvfyvs0.9dcot?θ

Tab.5 Comparisons between experimental results and theoretical predictions from different design procedures

a = shear span

A_{s} = area of bottom longitudial flexural reinforcement

A_{sh} = area of horizontal shear reinforcement

A_{sv} = area of transverse shear reinforcement or stirrup

b_{w} = web width of concrete beam

d = distance from the extreme compression fiber to the centroid of longitudinal tension reinforcement

f_{c} = cubic compression strength of concrete

f_{c}^{’} = cylindrical compression strength of concrete

f_{s} = stress in reinforcement

f_{sh} = stress in horizontal shear reinforcement

f_{sl} = stress in bottom longitudinal reinforcement

f_{sv} = stress in transverse shear reinforcement or stirrup

f_{t} = unaxial tensile strength of concrete

f_{u} = ultimate strength of reinforcement

f_{y} = yield strength of reinforcement

f_{yh} = yield strength of horizontal shear reinforcement

f_{yv} = yield strength of transverse shear reinforcement or stirrup

h = depth of beam

M = applied bending moment

N = applied axial force

s_{h} = spacing of horizontal shear reinforcement

s_{k} = spacing of transverse shear reinforcement or stirrup

V = applied shear force

V_{c} = contribution of concrete to shear strength

V_{cal} = calculated shear strength

V_{exp} = experimentallly observed shear strength

θ = inclination of concrete strut

ρ_{h} = ratio of horizontal shear reinforcement, ρ_{h} = A_{sh}/b_{w}s_{h}

ρ_{1} = ratio of bottom longitudinal flexural reinforcement, ρ_{t} = A_{s}/b_{w}d

ρ_{t} = ratio of transverse shear reinforcement, ρ_{t} = A_{sv}/b_{w}s_{k}

Tab.6 Notations

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2

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