scholarly journals Analysis of Prestressing in Precast Prestressed Concrete Beams

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jakub Kraľovanec ◽  
Martin Moravčík ◽  
Jozef Jošt
Keyword(s):  
Numerical Analysis ◽  
Service Life ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Direct Methods ◽  
Actual State ◽  
Indirect Methods ◽  
Remaining Service Life ◽  
Prestressing Force ◽  
Precast Prestressed Concrete

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.

scholarly journals Verification of Actual Prestressing in Existing Pre-Tensioned Members

2021 ◽  
Vol 11 (13) ◽  
pp. 5971
Author(s):  
Jakub Kraľovanec ◽  
František Bahleda ◽  
Jozef Prokop ◽  
Martin Moravčík ◽  
Miroslav Neslušan
Keyword(s):  
Service Life ◽  
Prestressed Concrete ◽  
Concrete Structure ◽  
Comparative Method ◽  
Design Procedure ◽  
Experimental Program ◽  
Actual State ◽  
Prestress Losses ◽  
Remaining Service Life ◽  
Prestressing Force

In the case of prestressed concrete structures, information about the actual state of prestressing is an important basis for determining their load-carrying capacity as well as remaining service life. During the service life of the prestressed concrete structure, the initial level of prestressing is inevitably reduced as a result of the actions of various factors. These reductions of prestressing force are considered as prestress losses, which are influenced by construction stages, used materials, prestressing technology, or required length of service life. Available standards enable the determination of the expected values of prestress losses. Ultimately, their calculation is part of the design procedure of every prestressed concrete structure. However, aging and often neglected infrastructure in Europe is also exposed to factors, such as environmental distress, that are not considered in standard calculations. Therefore, verified and reliable methods for determining the actual state of prestressing are needed. This paper presents an experimental program of an indirect method for the evaluation of the value of prestressing force in seven prestressed concrete sleepers. Particularly, the non-destructive saw-cut method as a pivotal object of this study is performed and assessed. Furthermore, the Barkhausen noise technique is used as a comparative method. Subsequently, the experimental campaign is supported by the numerical analysis performed in the ATENA 3D software. Finally, the experimentally determined values of residual prestressing force are compared to the expected level of prestressing according to Eurocodes.

Nonlinear numerical analysis of prestressed concrete beams and slabs

2020 ◽  
Vol 223 ◽  
pp. 111187
Author(s):  
Amilton Rodrigues da Silva ◽  
João Paulo de Souza Rosa
Keyword(s):  
Numerical Analysis ◽  
Prestressed Concrete ◽  
Concrete Beams

scholarly journals COMBINING EBR CFRP SHEET WITH PRESTRESSED NSM STEEL STRANDS TO ENHANCE THE STRUCTURAL BEHAVIOR OF PRESTRESSED CONCRETE BEAMS

2021 ◽  
Vol 27 (8) ◽  
pp. 637-650
Author(s):  
M. Obaydullah ◽  
Mohd Zamin Jumaat ◽  
U. Johnson Alengaram ◽  
Md. Humayun Kabir ◽  
Muhammad Harunur Rashid
Keyword(s):  
Prestressed Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Element Model ◽  
Control Specimen ◽  
Flexural Performance ◽  
Flexural Failure ◽  
Prestressing Force ◽  
Cfrp Sheet ◽  
Strengthening Technique

In this study, a combined strengthening technique is used to improve the flexural performance of prestressed concrete beams using CFRP sheets as EBR and prestressed steel strands as NSM. Seven prestressed beams were tested under four-point loading with one control specimen, one EBR CFRP sheet strengthened specimen, one NSM steel strand without prestress strengthened specimen and four specimens strengthened with a combination of EBR CFRP sheet and NSM steel strands prestressed from 0% to 70% of their tensile strength. The flexural responses and failure modes of the specimens were investigated and the variations due to the level of prestressing force in the PNSM steel strands were also assessed. A finite element model (FEM) was developed using ABAQUS to verify the flexural responses of the strengthened specimens. The test results revealed that the combined strengthening technique remarkably enhanced the flexural performance of the specimens. The serviceability, first crack, yield, and ultimate load capacities improved up to 44%, 49%, 55% and 70%, respectively when compared with the control specimen. The combined technique also ensured the flexural failure of the specimens with significant enhancement in stiffness and energy absorption. The results of the FEM model exhibited excellent agreement with the experimental results.

Large-scale fatigue tests on prestressed concrete beams

2021 ◽  
Author(s):  
Dennis Birkner ◽  
Steffen Marx
Keyword(s):  
Numerical Analysis ◽  
Cross Section ◽  
Prestressed Concrete ◽  
Large Scale ◽  
Concrete Beams ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Beam Specimen ◽  
The Cross ◽  
Number Of Cycles

<p>For a better estimation of the fatigue lifetime of real structures, tests on large-scale beam specimens are more suitable than on common cylindrical specimens, since effects like local stiffness changes and stress redistributions can be reproduced more realistically. This article presents an experimental setup for large-scale concrete beams subjected to fatigue loading. Additionally, the fatigue tests are simulated with a numerical model. The results of the numerical analysis show a successively increasing damage propagating from the edge into the inner part of the cross-section in the mid span with increasing number of cycles. This results in stress redistributions which extend the lifetime of the structure. The evaluation of the experimental investigation on the first beam specimen shows a larger stiffness degradation at the upper edge than in the centre of the cross-section as well as increasing strains at this location. This matches the expected effects from the numerical analysis.</p>

Beams prestressed with unbonded tendons at ultimate

1996 ◽  
Vol 23 (6) ◽  
pp. 1220-1230 ◽  
Author(s):  
Marco Andrea Pisani ◽  
Emilio Nicoli
Keyword(s):  
Numerical Analysis ◽  
Key Words ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Experimental Tests ◽  
Safety Factors ◽  
Unbonded Tendons ◽  
External Tendons ◽  
Simplified Method ◽  
Good Agreement

This paper presents a numerical investigation on beams and slabs prestressed with either unbonded internal or external tendons. Twenty-three experimental tests (beams and slabs prestressed with unbonded internal tendons) were numerically simulated to verify the reliability of the numerical algorithm adopted. The good agreement established enables us to study the behaviour of these beams in depth and to compare it with the behaviour of similar beams prestressed with external tendons. The numerical analyses were then repeated after including the safety factors related to the materials. The outputs were then compared with the results adopted by making use of the simplified method suggested by Eurocode E.C.2 Part 1-5, to check the size of the error involved in the adoption of the latter. Key words: numerical analysis, unbonded internal tendons, external tendons, European Prestandard, prestressed concrete, beams, post-tensioned.

Sign in / Sign up

Export Citation Format

Share Document