Mechanical Model for Shear Friction Capacity of Concrete at Construction Joints

Abstract

is study examined the reliability and limitations of code equations for determining the shear friction strength of a concrete interface with construction joints. is was achieved by examining the code equations (ACI 318-14, AASHTO, and fib 2010) and comparing the results predicted by equations with experimental data compiled from 207 push-off specimens (133 rough and 74 smooth construction joints). e integrated mechanical model for the monolithic interface, derived from the upper-bound theorem of concrete plasticity, was also modified to estimate the shear friction strength of the construction joints. e upper limit for shear friction strength was formulated from a concrete crushing failure limit on the strut-and-tie action along the interfacial plane, to avoid overestimating the shear transfer capacity of transverse reinforcement with a high clamping force. Code equations are highly conservative and dispersive in predicting the shear friction strength of rough construction joints and yield large scattering in the data for the ratios between the measured and predicted shear friction strengths. e predictions obtained using the proposed model agreed well with test results, indicating correlating trends with the test results for evaluating the effects of various parameters on the shear friction strength of rough construction joints. According to the proposed model, the values of cohesion and coefficient of friction for concrete could be determined as 0.11 (f c ′ ) 0.65 and 0.64, respectively, for smooth construction joints and 0.27 (f c ′ ) 0.65 and 0.95, respectively, for rough construction joints, where f c ′ is the compressive strength of concrete.

Service Life Prediction of Precast Concrete Structures Exposed to Chloride Environment

“…Unlike in components, shear force can transfer across the connection interface with several mechanisms, including friction induced by axial force and clamping stress, concrete cohesion, and dowel action of reinforcement [36]. Among them, shear friction is the most widely accepted one [58], but models based on it may be too conservative [59], and an improved model that incorporates concrete cohesion in can be written as [60]…”

“…where ρ c is the density of concrete in kg/m 3 and ϕ ′ is the frictional angle mentioned before, which can be chosen between 29.4°and 44.5° [60]. However, the aforementioned models for the interface shear strength do not include the influence of corrosion, and no existing model has been proposed to consider this problem.…”

Effectiveness of polypropylene fibres as shear reinforcement in structural elements

“…Finally, to validate the determined µ and b, they were compared in Table 3-17 with those µ and b suggested by MC2010, Climaco and Regan [201], and Seung-Jun Kwon et al [202] for rough surfaces. To supplement Table 3- The present experimental results always provided slightly higher µ and b coefficients than those recommended by MC2010, which were lower than the other expressions.…”