Flexural Strength of Prestressed Concrete Members

Skogman, Brian C.; Tadros, Maher K.; Grasmick, Ronald

doi:10.15554/pcij.09011988.96.123

Cited by 13 publications

(12 citation statements)

References 6 publications

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“…In the ACI318-14 code, it is specified that the net tensile stress of the prestressing strands (Df ps ) shall not exceed 250 MPa for the Class C PSC members to ensure proper crack control at the service loads. In order to estimate the net tensile stress of the prestressing strands (Df ps ) in the Class C flexural members under the service load conditions, the cracked section analysis should be essentially conducted, which unfortunately requires very complex and time-consuming iterative calculations, as pointed out by Skogman et al (1988). and Mast et al (2008).…”

Section: Introductionmentioning

confidence: 99%

Control of Tensile Stress in Prestressed Concrete Members Under Service Loads

Lee¹,

Han²,

Joo³

et al. 2018

Int J Concr Struct Mater

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In current design codes, crack control design criterion for prestressed concrete (PSC) members is stricter than conventional reinforced concrete (RC) members. In particular, it is stipulated that the net tensile stress of prestressing strands should be controlled under 250 MPa in the serviceability design of PSC members belonging to the Class C category section that is expected to be cracked due to flexure under service load conditions as defined in ACI318 code. Thus, the cracked section analysis is essentially required to estimate the tensile stress of the prestressing strands under the service loads, which requires very complex iterative calculations, thereby causing many difficulties in the applications of the Class C PSC members in practice. Thus, this study proposed a simple method to estimate the net tensile stress of the prestressing strands (Df ps ) under the service load conditions, and also provided a summary table to be used for checking whether the net tensile stress (Df ps ) exceeds the stress limit (250 or 350 MPa) with respect to the magnitude of effective prestress (f se ).

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Section: Introductionmentioning

confidence: 99%

Control of Tensile Stress in Prestressed Concrete Members Under Service Loads

Lee¹,

Han²,

Joo³

et al. 2018

Int J Concr Struct Mater

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“…Research studies and knowledge of prestressed LWC are, however, very limited, as prestressed concrete construction has mainly involved normal-weight concrete (NWC) (Bennett and Veerasubramanian, 1972;Collins and Mitchell, 1991;Harajli and Naaman, 1985;Mo and Chien, 1993;Taylor et al, 1978;Warwaruk et al, 1962;Wu et al, 2010). In addition, all the design equations used to predict the stress of bonded prestressing strands at the ultimate strength of beams are empirically derived and verified using test data on NWC beams (ACI, 2011;Harajli and Naaman, 1985;Loov, 1988;Skogman et al, 1988). Approximate steel strains are then computed from conditions of compatibility and equilibrium.…”

Section: Introductionmentioning

confidence: 99%

“…Flexural capacity measured from eight prestressed LWC beams was compared with that of pre-tensioned NWC beams compiled from the available literature (Bennett and Veerasubramanian, 1972;Harajli and Naaman, 1985) and predictions obtained using the equivalent stress block specified in ACI 318-11 (ACI, 2011) combined with ultimate stresses proposed for bonded strands and the non-linear strain compatibility analysis. The empirical equations proposed by the ACI (2011), Harajli and Naaman (1985), Loov (1988) and Skogman et al (1988) were adopted for different sources for the stress of bonded tendons at the ultimate strength of prestressed NWC beams.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, several investigations (ACI, 2011;Harajli and Naaman, 1985;Loov, 1988;Skogman et al, 1988) have been conducted to develop a reliable model for f ps , which must be estimated to easily predict the flexural capacity of prestressed beams.…”

mentioning

confidence: 99%

“…The empirically derived formulas to evaluate f ps (ACI, 2011;Harajli and Naaman, 1985;Loov, 1988;Skogman et al, 1988) are fully summarised in the literature (Skogman et al, 1988). These formulas, (apart from that proposed in ACI 318-11), show that f ps is strongly dependent on the depth of the neutral axis.…”

mentioning

confidence: 99%

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Flexural tests on pre-tensioned lightweight concrete beams

Yang

Mun

Lee³

2014

Proceedings of the Institution of Civil Engineers - Structures

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Eight pre-tensioned beams made using lightweight concrete with a design compressive strength of 35 MPa were tested under two symmetrical third-point concentrated loads. The main variables investigated were the eccentricity and effective prestress of the strands and the partial prestressing ratio. The flexural capacity of the beam specimens was compared with predictions obtained from simple equations using the equivalent stress block combined with different formulas proposed for the stress of bonded tendons at the ultimate strength of beams and from non-linear strain compatibility analysis. Test results showed that the normalised flexural capacity measured from pre-tensioned lightweight concrete beams with a reinforcing index below 0 . 15 was comparable to that of pre-tensioned normalweight concrete beams with a similar reinforcing index, while that of a pre-tensioned lightweight concrete beam with a reinforcing index of 0 . 207 was lower than that of pre-tensioned normal weight concrete beams with a reinforcing index of 0 . 2. As a result, the increasing rate of normalised flexural capacity against the reinforcing index in pre-tensioned lightweight concrete beams was slightly lower than that observed in pre-tensioned normal weight concrete beams. The flexural capacity of pre-tensioned concrete beams predicted using an equivalent stress block was marginally influenced by the values determined from different formulas for the stress of bonded tendons at the ultimate strength of beams, although the ratio of the measured and predicted flexural capacities was commonly lower in pre-tensioned lightweight concrete beams than in pre-tensioned normal weight concrete beams.

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Design method for checking tensile stresses under service loads in cracked prestressed concrete members with 2,400‐MPa strands

Joo

Han

Lee

et al. 2019

Structural Design Tall Build

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SummaryThe ACI 318‐14 building code requirements specify that the net tensile stresses of prestressing strands under service loads (Δfps) shall be limited to 250 MPa for proper crack control of prestressed concrete (PC) members which are classified as Class C. However, as high‐strength prestressing strands with a tensile strength of 2,400 MPa have recently been developed and applied to PC members, this requirement needs to be reviewed. In this study, experiments and analysis were carried out in order to investigate the Δfps of PC members with the recently developed 2400 MPa strands, and in the test, the strain distributions, flexural crack widths, and stress change in bonded prestressed reinforcement were measured in detail according to the applied loads. In addition, the minimum magnitudes of effective prestress to satisfy the stress limitation of the net tensile stress of prestressing strands specified in the current design code were estimated using a nonlinear flexural analysis model, and a simplified design equation was proposed for a simple calculation of the Δfps at the design stage.

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Flexural Strength of Prestressed Concrete Members

Cited by 13 publications

References 6 publications

Control of Tensile Stress in Prestressed Concrete Members Under Service Loads

Control of Tensile Stress in Prestressed Concrete Members Under Service Loads

Flexural tests on pre-tensioned lightweight concrete beams

Design method for checking tensile stresses under service loads in cracked prestressed concrete members with 2,400‐MPa strands

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