Axial load–moment interaction diagram of full-scale circular LWSCC columns reinforced with BFRP and GFRP bars and spirals: Experimental and theoretical investigations

The capacity-to-torque ratio, Kt, has been used in the design of helical piles and anchors for over half a century. Numerous research efforts have been conducted to accurately predict this capaci-ty-to-torque ratio. However, almost of all these Kt factors are based on shaft geometry alone. The ca-pacity-to-torque ratio described herein was found to depend on the shaft diameter, shaft geometry, helix configuration, axial load direction, and installation torque. In this study, 799 full scale static load tests in compression and tension were conducted on helical piles of varying shaft diameters, shaft geometry, and helix configurations in different soil types (sand, clay, and weathered bedrock). The collected data were used to study the effect of these variables on the capacity-to-torque ratio and resulted in developing a more reliable capacity-to-torque ratio, Km, that considers the effect of the variables mentioned above. The study shows that the published Kt values in AC358 (ICC-ES Acceptance Criteria for Helical Piles Systems and Devices) underestimate the pile capacity at low torque and overestimate it at high torque. In addition, and based on probability analysis, the predicted capacity using the modified Km results in a higher degree of accuracy than the one based on the published Kt values in AC358.

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Parametric study of the strength of reinforced concrete polygonal sections submitted to oblique composite flexion

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952020000500012 ◽

2020 ◽

Vol 13 (5) ◽

Author(s):

Lucas Peres de Souza ◽

Marco André Argenta

Keyword(s):

Reinforced Concrete ◽

Axial Load ◽

Bending Strength ◽

Computational Algorithm ◽

Bending Moment ◽

Failure Surface ◽

Surface Shape ◽

Axial Loads ◽

Interaction Diagram ◽

Cylinder Strength

abstract: This work aims to verify the influence of characteristic compressive cylinder strength ( f c k), section geometry and eccentric axial load on the strength of square, cross, “T” and “L” reinforced concrete sections, under oblique composite flexion. A computational algorithm was created to calculate sections interaction diagram of bending strength, taking into account NBR 6118 idealized parabola-rectangle stress-strain relationships for 20 to 90 MPa f c k concretes. The results show that f c k influence is stronger for higher values of axial load and that the failure surface shape in interaction diagrams depends directly on the f c k and on the rebars distribution in the section. Furthermore, under lower compressive axial loads, higher oblique composite flexion strengths are reached when there is more reinforcement area in tension regions but, as the compression increases, the reinforcement presence and larger concrete areas in compression zones provide higher bending moment strengths.

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