Shear strength of slender SCC beams - possible differences from VC beams

In comparison with vibrated concrete (VC) of the same strength class, self-compacting concrete (SCC) typically has a lower coarse aggregate content and, eventually, a smaller maximum aggregate size. This may reduce the aggregate interlock between the fracture surfaces in SCC. Since the aggregate interlock plays an important role in the shear strength of slender beams, SCC beams may have a shear strength lower than that of similar VC beams.

This article summarizes experimental studies on the shear strength of reinforced SCC slender beams without and with shear reinforcement. The shear strengths of SCC beams are compared with the ones of VC beams and also to the calculated ones according to different code procedures. It is shown that powder-type SCC beams tend to have lower shear strength than similar VC beams and that the difference depends upon the concretes composition and the characteristics of the beams.

Keywords:
self-compacting concrete; slender beams; shear strength

Authorship

T. L. Resende

Universidade Federal dos Vales do Jequitinhonha e Mucuri, Instituto de Ciência, Engenharia e Tecnologia, Teófilo Otoni, MG, Brasil. thomas.lima@ufvjm.edu.brUniversidade Federal dos Vales do Jequitinhonha e MucuriBrazilTeófilo Otoni, MG, BrazilUniversidade Federal dos Vales do Jequitinhonha e Mucuri, Instituto de Ciência, Engenharia e Tecnologia, Teófilo Otoni, MG, Brasil. thomas.lima@ufvjm.edu.br

L. C. D. Shehata

Universidade Federal Fluminense, Departamento de Engenharia Civil, Niterói, RJ, Brasil. lidiashehata@vm.uff.brUniversidade Federal FluminenseBrazilNiterói, RJ, BrazilUniversidade Federal Fluminense, Departamento de Engenharia Civil, Niterói, RJ, Brasil. lidiashehata@vm.uff.br

I. A. E. M. Shehata

Universidade Federal do Rio de Janeiro, COPPE, Programa de Engenharia Civil, Rio de Janeiro, RJ, Brasil. ibrahim@coc.ufrj.brUniversidade Federal do Rio de JaneiroBrazilRio de Janeiro, RJ, BrazilUniversidade Federal do Rio de Janeiro, COPPE, Programa de Engenharia Civil, Rio de Janeiro, RJ, Brasil. ibrahim@coc.ufrj.br

SCIMAGO INSTITUTIONS RANKINGS

Figures | Tables

Figures (9)
Tables (3)

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Figure 1
Comparison between the ultimate shear stress of SCC and VC beams tested by Hassan, Hossain and Lachemi [¹³[13] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Behavior of full scale self-consolidating concrete beams in shear, Cement & Concrete Composites, v.30, n.7, 2008, p. 588-596.,¹⁴[14] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Strength, cracking and deflection performance of large-scale self-consolidating concrete beams subjected to shear failure, Engineering Structures, v.32, n.5, 2010, p. 1262-1271.] with A_s/(b_wh)=1.0%

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Figure 2
Comparison between the ultimate shear stress of SCC and VC beams tested by Hassan, Hossain and Lachemi [¹³[13] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Behavior of full scale self-consolidating concrete beams in shear, Cement & Concrete Composites, v.30, n.7, 2008, p. 588-596.,¹⁴[14] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Strength, cracking and deflection performance of large-scale self-consolidating concrete beams subjected to shear failure, Engineering Structures, v.32, n.5, 2010, p. 1262-1271.] with A_s/(b_wh)=2.0%

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Figure 3
Comparison between the normalized shear strength of VC and SCC beams tested by Lin and Chen [18] with a/d=3.0

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Figure 4
Normalized shear strength of the SCC beams with different types of coarse aggregate and ρ=1.68% tested by Safan [¹¹[11] Safan, M. A., Shear strength of concrete beams cast with self-compacting concrete containing different fillers and coarse aggregates, Canadian Journal of Civil Engineering v.39, n.7, 2012, p. 760-770.]

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Figure 5
Comparison of the ultimate shear stresses of high strength SCC and VC beams with f_c≅ 70MPa and small values of ρ_wf_yw [¹²[12] Resende, T. L., Shehata, L.C.D., Shehata, I.A.E.M., Shear strength of self-compacting concrete beams with small amounts of stirrups, Structural Concrete (accepted for publication, DOI: 10.1002/suco.201400084), 2015.
https://doi.org/10.1002/suco.201400084... ]

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Figure 6
Values of V_u/V_R of beams without shear reinforcement as a function of V_u/(b_wd)

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Figure 7
a Values of V_u/V_R of beams with shear reinforcement as a function of V_u/(b_wd) (Continue)

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Figure 7b
Values of V_u/V_R of beams with shear reinforcement as a function of V_u/(b_wd) (Continuation)

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Figure 8
Values of ρ_w,minf_ywk specified in different codes as a function of f_ck

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Table 1
Ranges of relevant parameters of the beams

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Table 2
Summary of procedures for shear strength calculation

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Table 3
Statistical data of V_u/V_R

Figure 1 Comparison between the ultimate shear stress of SCC and VC beams tested by Hassan, Hossain and Lachemi [¹³[13] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Behavior of full scale self-consolidating concrete beams in shear, Cement & Concrete Composites, v.30, n.7, 2008, p. 588-596.,¹⁴[14] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Strength, cracking and deflection performance of large-scale self-consolidating concrete beams subjected to shear failure, Engineering Structures, v.32, n.5, 2010, p. 1262-1271.] with A_s/(b_wh)=1.0%

Figure 2 Comparison between the ultimate shear stress of SCC and VC beams tested by Hassan, Hossain and Lachemi [¹³[13] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Behavior of full scale self-consolidating concrete beams in shear, Cement & Concrete Composites, v.30, n.7, 2008, p. 588-596.,¹⁴[14] Hassan, A.A.A., Hossain, K.M.A., Lachemi, M., Strength, cracking and deflection performance of large-scale self-consolidating concrete beams subjected to shear failure, Engineering Structures, v.32, n.5, 2010, p. 1262-1271.] with A_s/(b_wh)=2.0%

Figure 3 Comparison between the normalized shear strength of VC and SCC beams tested by Lin and Chen [18] with a/d=3.0

Figure 4 Normalized shear strength of the SCC beams with different types of coarse aggregate and ρ=1.68% tested by Safan [¹¹[11] Safan, M. A., Shear strength of concrete beams cast with self-compacting concrete containing different fillers and coarse aggregates, Canadian Journal of Civil Engineering v.39, n.7, 2012, p. 760-770.]

Figure 5 Comparison of the ultimate shear stresses of high strength SCC and VC beams with f_c≅ 70MPa and small values of ρ_wf_yw [¹²[12] Resende, T. L., Shehata, L.C.D., Shehata, I.A.E.M., Shear strength of self-compacting concrete beams with small amounts of stirrups, Structural Concrete (accepted for publication, DOI: 10.1002/suco.201400084), 2015.
https://doi.org/10.1002/suco.201400084... ]

Figure 6 Values of V_u/V_R of beams without shear reinforcement as a function of V_u/(b_wd)

Figure 7 a Values of V_u/V_R of beams with shear reinforcement as a function of V_u/(b_wd) (Continue)

Figure 7b Values of V_u/V_R of beams with shear reinforcement as a function of V_u/(b_wd) (Continuation)

Figure 8 Values of ρ_w,minf_ywk specified in different codes as a function of f_ck

Table 1 Ranges of relevant parameters of the beams

Parameter	Range	Parameter	Range
Shear span to effective depth ratio a/d	2.5 to 3.8	Effective depth to tensile reinforcement d (mm)	100 to 668
Cylinder compressive strength f_c (MPa)	25 to 75	Longitudinal tensile reinforcement ratio ρ (%)	1.0 to 4.5
Maximum aggregate size d_max(mm)	10 to 19	Transverse reinforcement index ρ_wf_yw (MPa)	0.0 to 1.8

Table 2 Summary of procedures for shear strength calculation

Procedure		θ (°)	V_R
ABNT NBR 6118:2014	Model I	45	V_c+V_s
ABNT NBR 6118:2014	Model II	30 to 45
ACI 318:2014*		45
EN 1992-1-1:2004**		21.8 to 45	V_c or V_s
FIB MC 2010***	Level I	30 to 45
	Level II	(20+10000ε_x) to 45
	Level III	(20+10000ε_x) to 45	V_c+V_s

^*
(exception to this limit is permitted in beams with ρ_w> ρ_w,min)
^**
< 2 ; ρ < 0.02
^***
; ε_x is the longitudinal strain at the mid-depth, approximated to half the strain in the tensile longitudinal reinforcement; V_R,max,θmin is the upper limit to the shear resistance correspondent to the limit stress in the diagonal concrete struts considering θ=θ_min. For members without transverse reinforcement, only Levels I and II are applicable

Table 3 Statistical data of V_u/V_R

Procedure	ρ_wf_yw= 0				ρ_wf_yw ≥ ρ_w,minf_ywk
Procedure	Average	Median	Coef. Var.	V_u/V_R<1	Average	Median	Coef. Var.	V_u/V_R<1
	SCC
NBR 6118:2014^I	—	—	—	—	1.55	1.59	0.172	0.0%
NBR 6118:2014^II	—	—	—	—	1.32	1.37	0.170	3.2%
ACI 318:2014^*	1.29	1.31	0.158	5.4%	1.64	1.75	0.228	5.7%
ACI 318:2014	1.26	1.29	0.149	7.1%	1.56	1.62	0.225	8.6%
EN 1992-1-1:2004	1.05	1.04	0.116	32%	1.49	1.46	0.215	0.0%
FIB MC 2010^I	1.64	1.63	0.145	0.0%	2.14	2.11	0.215	0.0%
FIB MC 2010^II	1.23	1.22	0.118	1.8%	1.90	1.83	0.237	0.0%
FIB MC 2010^III	—	—	—	—	1.48	1.46	0.230	8.8%
	VC
NBR 6118:2014^I	—	—	—	—	1.58	1.52	0.178	0.0%
NBR 6118:2014^II	—	—	—	—	1.34	1.27	0.174	0.0%
ACI 318:2014^*	1.30	1.33	0.196	15%	1.74	1.64	0.168	0.0%
ACI 318:2014	1.26	1.31	0.187	15%	1.64	1.56	0.164	0.0%
EN 1992-1-1:2004	1.09	1.08	0.121	25%	1.46	1.46	0.175	0.0%
FIB MC 2010^I	1.81	1.73	0.153	0.0%	2.11	2.11	0.175	0.0%
FIB MC 2010^II	1.28	1.29	0.127	5.0%	1.85	1.85	0.184	0.0%
FIB MC 2010^III	—	—	—	—	1.50	1.46	0.177	0.0%

^*
More simplified formula of V_c ; I, II, III: Model or level of approximation

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Shear strength of slender SCC beams - possible differences from VC beams

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Mensagem

[TFN1] ^*
(exception to this limit is permitted in beams with ρ_w> ρ_w,min)

[TFN2] ^**
< 2 ; ρ < 0.02

[TFN3] ^***
; ε_x is the longitudinal strain at the mid-depth, approximated to half the strain in the tensile longitudinal reinforcement; V_R,max,θmin is the upper limit to the shear resistance correspondent to the limit stress in the diagonal concrete struts considering θ=θ_min. For members without transverse reinforcement, only Levels I and II are applicable