Expected compressive strength in precast, prestressed concrete design: A methodology to analyze...

[摘要] Concrete production relies on a combination ofequipment, materials, methods, and labor, each withits own associated variability. As a result, inherent statistical variability is expected in measured concretestrength results. Appropriate characterization of expectedconcrete strength is critical to ensure structural reliability1of precast concrete components as well as to ensure thatdesigners can predict deformational behavior (for example,camber and deflection) with sufficient accuracy to avoid fitor functional use issues. Producers often rely on AmericanConcrete Institute (ACI) design guidance1,2 to help select appropriate mixture proportions to meet the specifiedcompressive strength requirements; however, failure toconcurrently account for the expected modulus of elasticityin serviceability design may lead to undesirable service limitstate behavior.3 Camber, deflections, and prestress lossesin precast, prestressed concrete elements can differ greatlyfrom predicted values calculated using specified materialproperties. As an example, the significant differences inmeasured versus predicted camber and effective prestressare evident in Fig. 1 for actual prestressed concrete bulb-teebridge girders.4 To address this design challenge, previousresearchers5–8 have reviewed historical strength test recordsfor precast, prestressed concrete girders for selected U.S.regions and proposed single-factor empirical expressionsenabling designers to predict expected concrete compressivestrength as a function of specified strength.

[学科分类] 建筑学