Mechanical properties of large-diameter semi-grouted sleeve connections for railway platform canopies. (May 2023)

• Record Type: Journal Article
• Authors: Lin, Pengzhen; Hou, Shuailong; Wang, Yapeng
• Is Part Of: Structures. Volume 51(2023)
• Page Start: 171
• Page End: 184
• Publication Date: 2023-05
• Subjects: lb Embedded length of steel bar -- db Steel bar diameter -- ts Thickness of sleeve wall -- ds Outer diameter of sleeve -- As Inner surface area of sleeve -- Ab Embedded area of steel bar -- ub Bond stress -- un Radial stress of sleeve -- un.b Radial stress of steel bar -- fct Tensile strength of grouting material -- fg Ultimate compressive strength of grouting material -- GSC Grouted sleeve connector -- AE Anchorage end -- SE Screw thread end; Grouted sleeve -- Freeze–thaw cycle -- Bond strength -- The material constitutive -- The numerical simulation; Structural engineering -- Periodicals; 624.1
• DOI: 10.1016/j.istruc.2023.03.002
• Languages: English
• ISSNs: 2352-0124

Abstract

Abstract: To study the mechanical properties of a large-diameter semi-grouted sleeve of a railway platform canopy under a construction environment in winter, this study designed five groups of specimens for unidirectional tensile loading tests based on different curing conditions and freeze–thaw deterioration. The ultimate bearing capacity, strain distribution, failure mode, and grouting material damage were compared and analyzed under different working conditions. Based on the theory of thick-walled cylinders and the constraint analysis model, formulas for calculating the bond strength of grouted sleeve joints were developed to predict the bond strength of joints. Finally, a finite element model was established to study the effects of the steel bar embedded length, grouting material saturation, sleeve type, and steel bar diameter on the mechanical properties and damage of the specimens. The results indicate that the failure modes of GSC s include steel bar fracturing, steel bar slippage, sleeve fracturing, and screw thread failure. The ultimate bearing capacity of the GSC increased by 1.1% when the curing temperature increased from −5 to + 5 °C in the freeze–thaw group. Compared with the condition without freeze–thaw cycles, the short-term low-temperature curing freeze–thaw cycles increased the bond-strength of the grouted sleeve by 1.3%, whereas the high-temperature curing freeze–thaw cycles reduced the bond-strength by 3.5%. The maximum error between the proposed formula and the test result was less than 2%, which could be used to effectively predict the bond strength of a grouted sleeve joint. In addition, the ultimate bearing capacity of the GSC s decreased with decreases in the steel bar embedded length, grouting material saturation, and steel bar and sleeve diameter. When the steel bar embedded length and grouting material saturation decreased from 7d to 6.5d, the ultimate bearing capacity decreased by 9.4% and 2.5%, respectively, and the failure mode changed from steel bar to sleeve fracturing. Two methods, involving an increased wall thickness and a combined sleeve, are proposed for sleeve fracture defects. They effectively solve the problem of reduction in the ultimate bearing capacity owing to the increase in local stress caused by the insufficient length of the steel bar embedment and grouting material.