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| Date Asked: 04/06/2020 | Date Answered: 04/08/2020 |
| Poster: Anthony Mesiti | Company: Cardi Corporation |
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Question:
Please clarify “The composite system must meet the flexural and shear resistance requirements as indicated above” for the required moment capacity. The shear is written as “Required Factored Shear Capacity of FRP” while the moment is written as “Required Factored Moment Capacity” giving us reason to believe that the factored moment is the total factored moment between the T beam and the FRP. Is the moment of 850 k-ft, the total moment between the T beam and the FRP? Meaning total moment capacity of 850 k-ft minus moment capacity of T beam equals moment capacity FRP is to resist? Which would be less than the 850 k-ft moment. Please clarify the target moment capacity of the FRP? |
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Answer:
For moment – The specified 850 ft-kip is the total required moment capacity for the combination of the Tee-beam section plus the FRP composite system. Flexure for the concrete T-beam section shall be computed based on the design parameters stated in the contract specification. The total moment capacity of the T-beam section plus proposed FRP composite shall be computed per ACI 440.2R design procedure for FRP flexural strengthening and is a function of the strain compatibility between the FRP system and concrete T-beam, as well as the modulus of elasticity of the proposed FRP. As such, the two flexural capacity components are not additive. For shear – The specified 60 kips shear capacity is the required additional shear capacity to be provided by the FRP. Unlike moment design, shear capacity of the composite FRP and concrete T-beam system is additive and therefore the shear capacity of the FRP can be computed independent of the shear capacity of the concrete section. PLEASE NOTE – The specified target capacities are FACTORED capacities, and therefore represent the capacity with the appropriate reduction factors applied, as per AASHTO LRFD and ACI 440.2R. |
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