Flexural performance of pretensioned spun concrete piles reinforced with steel strands

Abstract

The application of pretensioned spun high-strength concrete (PHC) piles in high intensity seismic areas has so far been limited by insufficient horizontal load resistance and poor deformation capacity. A new type of pretensioned spun concrete pile with high strength and high elongation steel strands instead of steel bars has been developed. This paper presents the flexural performance evaluation of the new centrifugal spun concrete pile with steel strands (hereafter referred to as PSC pile). An experimental study is presented first, including the bending tests on six full-scale pile test specimens with three different pile diameters. The flexural performances of PHC and PSC piles are comparatively assessed in terms of crack resistance, ultimate bearing capacity, deformation capacity and failure mode. The results show that the new PSC piles have similar crack resistance, but higher ultimate bearing capacity and better deformation capacity under a flexural condition. Comparing to PHC piles which exhibit a brittle bending failure due to the rupture of prestressing steel bars, PSC piles demonstrate a ductile bending failure with a more gradual crushing of concrete in the compression zone. Following the experimental study, a theoretical model is developed to evaluate the flexural strength of the piles, and a simplified calculation equation for ultimate bending moment is proposed. Finally, a finite element model is also established to simulate the flexural performance of the piles and the modelling results are found to be in good agreement with the experimental results.

Investigation on Seismic Behavior of Prestressed Steel Strand Composite Reinforced High-Strength Concrete Column

“…Tian et al [10] have proposed a method with wide spacing and high-strength longitudinal bars, which simplifies the construction of node areas, reduces construction difficulties, and improves construction efficiency while ensuring construction quality. The widespread application of prestressing technology can draw insights from prefabricated prestressed bridge piers and prestressed steel strand piles [11][12][13][14][15]. Prestressed steel strands tackle issues related to the poor ductility of prestressed steel bars in ordinary prestressed piles, leading to compromised lateral resistance, flexural and shear ductility, and susceptibility to brittle failure.…”

Field Test Study on the Bearing Capacity of Extra-Long PHC Pipe Piles under Dynamic and Static Loads

“…A pretensioned prestressed high strength concrete pipe is called a PHC pile for short [1][2][3][4]. Its bearing capacity includes vertical bearing capacity, horizontal bearing capacity and seismic bearing capacity [5][6][7][8][9][10][11][12]. A single pile static load test is currently the most reliable method for a quality inspection of pile foundation engineering, and it is also a method that can measure the relationship between pile-soil stress and strain, and the results can be used as the basis for pile foundation engineering design [13].…”

Seismic performance of pretensioned centrifugal spun concrete piles with steel strands

“…PHC piles have been extensively used in foundation engineering in soft soil regions as a consequence of the advantages in terms of good quality control, high axial load-carrying capacity, efficient on-site construction and cost effectiveness. However, the helical grooved steel bars are generally used as the prestressing tendons in PHC piles, which have the disadvantage of poor tensile ductility with a rupture strain of only about 3.0% [1,2]. Moreover, the contact between the pier heads of the steel bars and the anchor holes of the end plates at both ends of the PHC piles is often insufficient, which results in uneven tensioning stresses and even premature brittle rupture of the prestressing steel bars.…”

“…In order to overcome the problem with limited tensile deformation ability of steel bars, methods of using steel strands with better elongation and higher strength as the prestressing tendons have been put forward [1,2], and piles using such prestressing steel strands, called as PSC piles, have been developed. Compared with common prestressed concrete round piles and octagonal piles [8][9][10], the initial pre-stresses in prestressing tendons and concrete in PSC piles are evenly distributed along the pile body due to the special anchorage structure.…”

“…The relative slippage between steel strands and pile body concrete is small even when a large lateral deformation occurs in the pile body. An experimental investigation into the flexural behavior of PSC piles under monotonic loading has been conducted [2], and the bending test results demonstrated that PSC piles with a smaller amount of prestressing tendons exhibited better deformation capacity and higher flexural capacity than PHC piles.…”