precast prestressed concrete
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Author(s):  
Amanda Pushka ◽  
Jonathan D Regehr ◽  
Graziano Fiorillo ◽  
Aftab Mufti ◽  
Basheer Hasan Algohi

Several provinces in Canada have modified the live load model specified in national bridge design codes to account for locally permitted trucks. Manitoba similarly introduced a live load model for the design of provincial bridges in accordance with AASHTO LRFD, the Modified HSS-25. This article presents truck weight datasets and methods used to develop Manitoba-specific live load statistics to conduct a reliability analysis for three typical simply supported structure types: precast prestressed concrete box girder, precast prestressed concrete I-girder and steel girder. The average reliability indices ranged from 4.69 to 4.95 with respect to the AASHTO LRFD live load statistics used to calibrate the code and 4.65 to 5.04 with respect to the Manitoba statistics. The results demonstrate a level of safety that exceeds the code requirements, indicating that structures designed to the HSS-25 potentially possess the structural capacity to withstand increased vehicular load effects for the considered bridge types.


2021 ◽  
Author(s):  
Antonio Cofini

Canada is facing a major crisis with the deterioration of its infrastructure (bridges, harbours, buildings, water structures, sewers, parking garages, etc.). Many of these structures were build using precast prestressed concrete members. These members may be under-strength because of deficiencies in design, increase in applied loads, loss of prestress, or damage due to the effects of corrosion, collision or military operations. Epoxy-bonding composite materials to the tension side of prestressed concrete girders is an effective technique for shear/flexural rehabilitation and strengthening of such members. To ensure successful and cost-effective applications of such materials, engineers need to improve their knowledge with respect to the actual behavior of full-size girders so that they can gain confidence on using these materials on structural strengthening and rehabilitation. This can be achieved by providing more data on testing-to-collapse and on field conditions full-scale prestressed girders strengthened using FRP materials. This study details the use of Carbon Fiber Reinforced Polymer (CFRP) Sheets to repair and strengthen precast presetressed concrete Double-Tee (DT) girders in flexure and shear. Three actual-size partially-damaged DT precast pretensioned girders were obtained from the manufacturer. All three of the girders were repaired and strengthened, and then tested to failure to determine flexural and shear capacities. The stems of two of these girders were strengthened in flexures using U-shape un-directional carbon fiber reinforced polymer sheets (CFRP), extending from the mid-span to the quarter points of the girders. Two girders were strengthened in shear the dapped ends using 0° wrapping technique around the stem, while the dapped ends of the third girder were strengthened using 0°/90° wrapping technique. Each girder was loaded incrementally up to failure using Jersey Barriers. This project summarizes the loading history and reports test results that can be further used to demonstrate the practicality of girder strengthening with CFRP sheets in field conditions.


2021 ◽  
Author(s):  
Antonio Cofini

Canada is facing a major crisis with the deterioration of its infrastructure (bridges, harbours, buildings, water structures, sewers, parking garages, etc.). Many of these structures were build using precast prestressed concrete members. These members may be under-strength because of deficiencies in design, increase in applied loads, loss of prestress, or damage due to the effects of corrosion, collision or military operations. Epoxy-bonding composite materials to the tension side of prestressed concrete girders is an effective technique for shear/flexural rehabilitation and strengthening of such members. To ensure successful and cost-effective applications of such materials, engineers need to improve their knowledge with respect to the actual behavior of full-size girders so that they can gain confidence on using these materials on structural strengthening and rehabilitation. This can be achieved by providing more data on testing-to-collapse and on field conditions full-scale prestressed girders strengthened using FRP materials. This study details the use of Carbon Fiber Reinforced Polymer (CFRP) Sheets to repair and strengthen precast presetressed concrete Double-Tee (DT) girders in flexure and shear. Three actual-size partially-damaged DT precast pretensioned girders were obtained from the manufacturer. All three of the girders were repaired and strengthened, and then tested to failure to determine flexural and shear capacities. The stems of two of these girders were strengthened in flexures using U-shape un-directional carbon fiber reinforced polymer sheets (CFRP), extending from the mid-span to the quarter points of the girders. Two girders were strengthened in shear the dapped ends using 0° wrapping technique around the stem, while the dapped ends of the third girder were strengthened using 0°/90° wrapping technique. Each girder was loaded incrementally up to failure using Jersey Barriers. This project summarizes the loading history and reports test results that can be further used to demonstrate the practicality of girder strengthening with CFRP sheets in field conditions.


Author(s):  
Saeed Gerami ◽  
Dagmar Svecova

The rehabilitation of structures is a complex process that involves many considerations. This paper presents results of a feasibility study on the use of precast prestressed concrete prisms (PCPs) as a near-surface mounted reinforcement for rehabilitation of cracked one-way slabs. The PCPs were cast with high-strength concrete and were concentrically prestressed by one 9 mm diameter stress-relieved seven-wire steel strand. Six identical one-way slabs with a length of 3000 mm were tested. They were loaded until cracking, then fully unloaded and rehabilitated with four PCPs before loading them to failure. Deflected profiles and crack widths of the slabs before and after rehabilitation were compared in this research. This rehabilitation method reduced the magnitude of deflection and crack width of the samples. The cracks induced in the first phase of loading before PCP rehabilitation appeared fully closed after the PCP rehabilitation until five times the original cracking loads of the slabs.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jakub Kraľovanec ◽  
Martin Moravčík ◽  
Jozef Jošt

Abstract Knowledge of prestressing force’s value is in the case of prestressed concrete structure the most important basis for defining load-carrying capacity and remaining service life. Numbers of prestressed concrete structures are about to reach their limit of service life and they are exhibiting signs of deterioration due to the conceptional errors, inadequate maintenance and environmental distress. All of these factors negatively influence the actual state of prestressing. Thus, it is essential to determine the value of prestressing force considering the degradation of materials, such as corrosion of prestressing strands or wires. While assessing structure in service, it is difficult to apply magnetoelastic sensors or use other direct methods for determining the state of prestressing. Hence, the indirect methods enable to analytically calculate the prestressing force based on the results of measurement, e.g. strain, stress, deflection, or width of the crack. The present paper focuses on numerical analysis of prestressing in a twosome of precast prestressed concrete beams. For the numerical analysis, two indirect methods are applied, specifically Saw-cut method and Crack initiation method. Finally, the results are discussed and recommendations for the experimental campaign are summarized.


2021 ◽  
Author(s):  
Chuanbing (Shawn) Sun ◽  
Nahid Farzana ◽  
Dinesha Kuruppuarachchi ◽  
Oluwatobi Babarinde

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