Shear design of high strength concrete prestressed girders

doi:10.1007/s11709-014-0087-7

Front. Struct. Civ. Eng.

2014, Vol. 8

Issue (4) : 373-387 https://doi.org/10.1007/s11709-014-0087-7

RESEARCH ARTICLE

Shear design of high strength concrete prestressed girders

Emad L. LABIB¹, Hemant B. DHONDE², Thomas T. C. HSU³, Y. L. MO³(

)

¹. Oil Field Development Engineering LLC, Houston, TX 77079, USA
². Department of Civil Engineering, VIIT, University of Pune, Pune 411007, India
³. Department of Civil and Environmental Engineering, University of Houston, Houston, TX 77004, USA

Download: PDF(1660 KB) HTML
Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks

Abstract

Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m (25 feet) long girders made with high strength concrete were designed, cast, and tested at the University of Houston (UH) to study the ultimate shear strength and the shear concrete contribution (V_c) as a function of concrete strength ( $f ′ \hskip -3pt c$ ). A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength ( $f ′ \hskip -3pt c$ ), web area (b_wd), shear span to effective depth ratio (a/d), and percentage of transverse steel (ρ_t). The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17000 psi) ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD (2010) code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa (17000 psi).

Keywords shear design high strength concrete prestressed girders full-scale tests

Corresponding Author(s): Y. L. MO

Online First Date: 12 December 2014 Issue Date: 12 January 2015

Cite this article:

Emad L. LABIB,Hemant B. DHONDE,Thomas T. C. HSU, et al. Shear design of high strength concrete prestressed girders[J]. Front. Struct. Civ. Eng., 2014, 8(4): 373-387.

URL:

https://academic.hep.com.cn/fsce/EN/10.1007/s11709-014-0087-7
https://academic.hep.com.cn/fsce/EN/Y2014/V8/I4/373

Fig.1 Determination of number of stirrups for steel contribution

V s

in a PC girder. (a) Smeared stirrups method; (b) minimum shear resistance method

Tab.1 Concrete mix proportions used for casting PC girder specimens

Fig.2 Layout of Tx54 girders with top deck (unit: mm)

Fig.3 Full scale and scaled down cross-sections of PC girders. (a) Full scale cross-section; (b) scaled down cross-section (unit: mm)

Fig.4 Cross-section and reinforcement details for modified Tx28 girders (unit: mm)

Fig.5 Cross-section and reinforcement details for modified Tx28 girders C2 and C4 (unit: mm)

Fig.6 Positions of loading actuators and load cells for various girder specimens. (a) A1, F1, F3, C1, and C3 with a/d equals 1.77; (b) F2 and F4 with a/d equals 2.25; (c) A2, C2 and C4 with a/d equals 3.00 (unit: mm)

Tab.2 Reinforcement details for PC girder specimens

Fig.7 Test setup for high strength PC I-girders

Fig.8 Typical LVDT rosette installed on girder specimens at end zone

Fig.9 Shear force vs. net deflection curves for Group A PC girders

Fig.10 Shear force vs. net deflection curves for Group F PC girders

Fig.11 Shear force vs. net deflection curves for Group C PC girders

girder I.D.	expt. ult. shear strength V_test/kN	a/d	$f ′ c$ /MPa	transverse steel				expt. concrete contribution V_c/kN	expt. failure mode
girder I.D.	expt. ult. shear strength V_test/kN	a/d	$f ′ c$ /MPa	ρ/%	balanced V_s, Eq. (7)/KN	avg. strain ε_avg	expt. V_s/kN	expt. concrete contribution V_c/kN	expt. failure mode
A1	north 632.14	1.77	48.3	1.76	231.44	ε_y	256.22	375.92	web-shear
A1	south 519.82	1.77	48.3	1.76	231.44	-	-	-	web-shear
A2	north 576.04	3.00	49.6	2.30	313.73	ε_y	359.82	216.23	web-shear
A2	south 551.77	3.00	49.6	2.30	313.73	ε_y	359.82	191.95	web-shear
F1	north 919.91	1.77	91.0	1.88	317.83	ε_y	279.35	640.56	web-shear
F1	south 896.72	1.77	91.0	1.88	317.83	ε_y	279.35	617.37	web-shear
F2	north 885.82	2.25	89.6	2.58	368.58	ε_y	415.15	470.67	web-shear
F2	south 841.83	2.25	89.6	2.58	368.58	ε_y	415.15	426.67	web-shear
F3	north 895.01	1.77	91.7	2.43	319.03	ε_y	385.84	509.17	web-shear
F3	south 904.99	1.77	91.7	2.43	319.03	ε_y	385.84	519.15	web-shear
F4	north 723.73	2.25	90.3	3.31	370.00	0.70 ε_y	388.20	335.53	web-shear
F4	south 786.13	2.25	90.3	3.31	370.00	0.70 ε_y	388.20	397.94	web-shear
C1	north 851.39	1.77	108.2	2.58	346.65	0.90 ε_y	373.61	477.78	web-shear
C1	south 766.87	1.77	108.2	2.58	346.65	0.85 ε_y	352.88	414.00	web-shear
C2	north 858.51	3.00	103.4	3.18	452.87	ε_y	530.01	328.50	flexure-shear
C2	south 745.08	3.00	103.4	3.18	452.87	0.85 ε_y	450.52	294.56	flexure-shear
C3	north 971.22	1.77	116.5	3.44	359.64	0.90 ε_y	522.98	448.25	web-shear
C3	south 1032.6	1.77	116.5	3.44	359.64	0.90 ε_y	522.98	509.63	web-shear
C4	north 875.85	3.00	105.5	4.13	457.37	0.70 ε_y	499.71	376.14	flexure-shear
C4	south 775.77	3.00	105.5	4.13	457.37	0.70 ε_y	499.71	276.06	flexure-shear

Tab.3 Calculations of steel and concrete shear contribution

Fig.12 Variation of the normalized concrete shear contribution with shear span to depth ratio for PC girders

girder I.D.	expt. ult. shear strength V_test/kN	a/d	$f ′ c$ /MPa	transverse steel				expt. concrete contribution V_c/kN	expt. failure mode
girder I.D.	expt. ult. shear strength V_test/kN	a/d	$f ′ c$ /MPa	ρ/%	balanced V_s, Eq. (7)/KN	avg. strain ε_avg	expt. V_s/kN	expt. concrete contribution V_c/kN	expt. failure mode
A1	north 632.14	1.77	48.3	1.76	231.44	ε_y	256.22	375.92	web-shear
A1	south 519.82	1.77	48.3	1.76	231.44	-	-	-	web-shear
A2	north 576.04	3.00	49.6	2.30	313.73	ε_y	359.82	216.23	web-shear
A2	south 551.77	3.00	49.6	2.30	313.73	ε_y	359.82	191.95	web-shear
F1	north 919.91	1.77	91.0	1.88	317.83	ε_y	279.35	640.56	web-shear
F1	south 896.72	1.77	91.0	1.88	317.83	ε_y	279.35	617.37	web-shear
F2	north 885.82	2.25	89.6	2.58	368.58	ε_y	415.15	470.67	web-shear
F2	south 841.83	2.25	89.6	2.58	368.58	ε_y	415.15	426.67	web-shear
F3	north 895.01	1.77	91.7	2.43	319.03	ε_y	385.84	509.17	web-shear
F3	south 904.99	1.77	91.7	2.43	319.03	ε_y	385.84	519.15	web-shear
F4	north 723.73	2.25	90.3	3.31	370.00	0.70 ε_y	388.20	335.53	web-shear
F4	south 786.13	2.25	90.3	3.31	370.00	0.70 ε_y	388.20	397.94	web-shear
C1	north 851.39	1.77	108.2	2.58	346.65	0.90 ε_y	373.61	477.78	web-shear
C1	south 766.87	1.77	108.2	2.58	346.65	0.85 ε_y	352.88	414.00	web-shear
C2	north 858.51	3.00	103.4	3.18	452.87	ε_y	530.01	328.50	flexure-shear
C2	south 745.08	3.00	103.4	3.18	452.87	0.85 ε_y	450.52	294.56	flexure-shear
C3	north 971.22	1.77	116.5	3.44	359.64	0.90 ε_y	522.98	448.25	web-shear
C3	south 1032.6	1.77	116.5	3.44	359.64	0.90 ε_y	522.98	509.63	web-shear
C4	north 875.85	3.00	105.5	4.13	457.37	0.70 ε_y	499.71	376.14	flexure-shear
C4	south 775.77	3.00	105.5	4.13	457.37	0.70 ε_y	499.71	276.06	flexure-shear

Tab.4 Calculations of steel and concrete shear contribution

Fig.13 Variation of the normalized concrete shear contribution with shear span to depth ratio for PC girders

a	shear span, in.
A_v	cross sectional area of single stirrup, in²
b_w	width of the web of girder, in
d	effective depth from the centroid of the strands to the top compression fiber of the girder and not less than 80% of the total depth of the girder, in
d_v	effective shear depth per ASSHTO LRFD= 0.9d (assumed in this work)
$f c ′$	cylinder compressive strength of concrete, psi.
$f c ′$	square root of cylinder compressive strength of concrete (same unit as $f c ′$ )
$f y$	yielding strength in bare steel bars, psi
s	spacing of stirrups, in.
V_c	concrete contribution to shear resistance in girders, kips
V_s	steel contribution to shear resistance in girders, kips
V_n,max	maximum design shear capacity of prestressed girders, kips
V_test	experimental ultimate shear force in prestressed girders at failure, kips
$ρ$	transverse steel reinforcement ratio, %
$E s$	modulus of elasticity of a bare steel bar
V_p	contribution of draped strands to shear resistance in prestressed girders
$ε a v g$	average strain in transverse rebar measured using strain gauges in a girder test.

1	A Laskar, T T C Hsu, Y L Mo. Shear strength of prestressed concrete girders part 1: Experiments and shear design equations. ACI Structural Journal, 2010, 107(3): 330–339
2	A Belarbi, T T C Hsu. Constitutive laws of concrete in tension and reinforcing bars stiffened by concrete. ACI Structural Journal, 1994, 91(4): 465–474
3	A Belarbi, T T C Hsu. Constitutive Laws of Softened Concrete in Biaxial Tension-Compression. ACI Structural Journal, 1995, 92(5): 562–573
4	X B Pang, T T C Hsu. Fixed-angle softened-truss model for reinforced concrete. ACI Structural Journal, 1996, 93(2): 197–207
5	T T C Hsu, L X Zhang. Tension stiffening in reinforced concrete membrane elements. ACI Structural Journal, 1996, 93(1): 108–115
6	L X Zhang, T T C Hsu. Behavior and analysis of 100MPa concrete membrane elements. Journal of Structural Engineering, 1998, 124(1): 24–34
7	A Laskar, J Wang, T T C Hsu, Y L Mo. Rational Shear Provisions for AASHTO LRFD Specifications. Technical Report 0−4759−1 to Texas Department of Transportation, Department of Civil and Environmental Engineering, University of Houston, Houston, TX, 2007, 216
8	R E Loov. Shear Design of Uniformly Loaded Girders. Presented at the Sixth International Conference on Short and Medium Span Bridges, Vancouver, Canada, 2002-July-31
9	A Laskar. Shear behavior and design of prestressed concrete members. Dissertation for the Doctoral Degree. Houston: University of Houston, 2009, 322
10	TxDOT 0−4759−1. Rational Shear Provisions for AASHTO LRFD specifications. Technical Report 0−4759−1, by Laskar A, Wang J, Hsu T T C, Mo Y L. Texas Department of Transportation, TX, University of Houston, TX, 2007
11	ASTM C 494/C 494M−99. Standard Specification for Chemical Admixtures for Concrete. ASTM International, West Conshohocken, P A, 1999, 10
12	ACI-318. Building Code Requirements for Structural Concrete Commentary. American Concrete Institute, Farmington Hills, Michigan, 2011
13	AASHTO. AASHTO LRFD Bridge Design Specifications. 4th ed. American Association of State Highway and Transportation Officials (AASHTO), Washington, D C, 2010
14	E L Labib. Shear behavior and design of high strength concrete prestressed bridge girders. Dissertation for the Doctoral Degree. Houston: University of Houston, 2012, 592
15	E W Bennett, B M A Balasooriya. Shear strength of prestressed girders with thin webs failing in inclined compression. ACI Journal Proceedings, 1971, 69(3): 204–212
16	B V Rangan. Web crushing strength of reinforced and prestressed concrete girders. ACI Structural Journal, 1991, 88(1): 12–16
17	Z J Ma, M K Tadros, M Baishya. Shear behavior of pretensioned high-strength concrete bridge I-girders. ACI Structural Journal, 2000, 97(1): 185–193
18	NCHRP 549. Simplified Shear Design of Structural Concrete Members. NCHRP Report 549, Transportation Research, 2005
19	TxDOT 0-6152-2. Shear in High Strength Concrete Bridge Girders. Technical Report 0−6152−2, by E L Labib, B H Dhonde, R Howser, Y L Mo, T T C Hsu, A Ayoub. Texas Department of Transportation, Department of Civil and Environmental Engineering, University of Houston, Houston, TX, 2013, 303
20	G Hernandez. Strength of Prestressed Concrete Girders with Web Reinforcement. Report, the Engineering Experiment Station, University of Illinois, Urbana, Illinois, 1958, 135
21	A H Mattock, P H Kaar. Precast-prestressed concrete bridges – 4: Shear tests of continuous girders. Journal of the PCA Research Development Laboratories, 1961, 19–47
22	J M Hanson, C L Hulsbos. Overload Behavior of Pretensioned Prestressed Concrete I-Girders with Web Reinforcement. Highway Research Record 76, Highway Research Board, 1965, 1–31
23	A H Elzanaty, A H Nilson, F O Slate. Shear capacity of prestressed concrete girders using high-strength concrete. ACI Journal, 1986, 83(3): 359–368
24	M K Kaufman, J A Ramirez. Re-evaluation of ultimate shear behavior of high-strength concrete prestressed I-girders. ACI Structural Journal, 1988, 85(3): 295–303
25	J G MacGregor, M A Sozen, C P Siess. Strength and Behavior of Prestressed Concrete Girders with Web Reinforcement. Research Report, The Engineering Experiment Station, University of Illinois, Urbana, Illinois, 1960
26	R N Bruce. An experimental study of the action of web reinforcement in prestressed concrete girders. Dissertation for the Doctoral Degree. Champaign: University of Illinois Urbana, 1962
27	B S Lyngberg. Ultimate shear resistance of partially prestressed reinforced concrete I-girders. ACI Journal, 1976, 73(4): 214–222
28	I N Robertson, A J Durrani. Shear strength of prestressed concrete T girders with welded wire fabric as shear reinforcement. PCI Journal, 1987, 32(2): 46–61
29	M A Shahawy, B Batchelor. Shear behavior of full-scale prestressed concrete girders: Comparison between AASTHO specifications and LRFD code. PCI Journal, Precast/Prestressed Concrete Institute, 1996, 41(3): 48–62

[1]	Jun WU,Xuemei LIU. Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration of interface properties[J]. Front. Struct. Civ. Eng., 2015, 9(3): 323-340.
[2]	LI Min, QIAN Chunxiang, KAO Hongtao. Degradation of permeability resistance of high strength concrete after combustion[J]. Front. Struct. Civ. Eng., 2008, 2(3): 281-287.

Viewed

Full text

Abstract

Cited

Shared

Discussed