scholarly journals On the Effectiveness of Vibration-Based Monitoring for Integrity Management of Prestressed Structures

2021 ◽  
Vol 6 (12) ◽  
pp. 171
Author(s):  
Marco Andrea Pisani ◽  
Maria Pina Limongelli ◽  
Pier Francesco Giordano ◽  
Mattia Palermo
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Decision Makers ◽  
Reinforced Concrete Beams ◽  
Structural Element ◽  
Integrity Management ◽  
Large Research ◽  
Prestressed Beams ◽  
Prestressed Structures

In this paper, the effectiveness of vibration-based tests for the detection of damages for prestressed concrete beams is investigated. Despite large research efforts, discrepant and sometimes contradicting conclusions have been drawn regarding the efficacy and reliability of vibration-based monitoring for prestressed structures. Herein, a contribution to this discussion is provided by tackling the problem from a different perspective. Specifically, the question that this paper intends to answer is: “Do vibration-based tests support decision-makers in integrity management operations for prestressed elements?” The discussion is carried out by comparing the performance of prestressed and ordinary reinforced concrete beams with similar capacities. Both analytical and numerical case studies are considered. Results show that, for prestressed beams, in contrast to reinforced concrete beams, modal parameters can provide information regarding damage only when the structure is close to its ultimate conditions. This makes this information hardly useful for integrity management purposes and the effectiveness of vibration-based tests questionable for this type of structural element.

FLEXURAL DUCTILITY OF STRUCTURAL CONCRETE MEMBERS SUBJECTED TO LIMITED CYCLES OF REPEATED LOADING

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Nazar Oukaili ◽  
Mohammed Khattab
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Constant Load ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Structural Concrete ◽  
Concrete Members ◽  
Flexural Ductility ◽  
High Level

For structural concrete members that may expose to serious earthquake, overload or accident impact, the design of ductility must be given the same importance as the flexural strength. The aim of this investigation is to study the change in ductility of structural concrete flexural members during their exposure to limited cycles of repeated loading. Twenty full-scale beam specimens have been fabricated in to two identical groups; each group consisted of ten specimens. The first group was tested under monotonic static loading to failure and regarded as control beams, while the specimens of the second group were subjected to ten cycles of repeated loading with constant load interval, which ranged between 40% and 60% of ultimate load. Specimens in each group were categorized as follows: two traditional reinforced concrete specimens with different intensity of tension reinforcement; three partially prestressed specimens with bonded strands; three partially prestressed specimens with unbonded strands; and two fully prestressed concrete specimens. The main variable, which was considered for all specimens was the partial prestressing ratio (PPR). It was observed that, the ductility of reinforced concrete beams was insignificantly increased during subjecting to limited repeated loading. For fully prestressed and partially prestressed concrete beams with high level of PPR, the ductility was significantly enhanced, while, it was decreased for specimens with small level of PPR.

The Behavior of Reinforced and Pre-Stressed Concrete Beams under Elevated Temperature

2020 ◽  
Vol 47 ◽  
pp. 15-30
Author(s):  
Amr H. Badawy ◽  
Ahmed Hassan ◽  
Hala El-Kady ◽  
L.M. Abd-El Hafez
Keyword(s):  
Reinforced Concrete ◽  
Elevated Temperature ◽  
Prestressed Concrete ◽  
Mechanical Performance ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Second Phase ◽  
Prestressed Beam

The behavior of unbounded post tension and reinforced concrete beams under elevated temperature was presented. The experimental work was consisted of two major phases. In the first phase, the objective was studying the mechanical performance of prestressed beam, prestressed beam with steel addition and reinforced concrete beams respectively were studied. In the second phase, the residual mechanical performance of prestressed beam, prestressed beam with steel addition and reinforced concrete beams under elevated 400oC, for 120 minutes durations. The failure mechanisms, ultimate load capacity, and deflection at critical sections were monitored. The numerical prediction of the flexural behavior of the tested specimens is presented in this paper. This includes a comparison between the numerical and experimental test results according to ANSYS models. The results indicate that the prestressed beam with steel addition and reinforced concrete beams had higher resistance to beams under elevated 400oC than that of prestressed concrete beam in terms of ultimate capacity. It is also shown that the reinforced concrete beams have higher resistance to beams under elevated temperature than that of prestressed beam, prestressed beam with steel addition.

Flexural Behavior of Concrete Beam Reinforced with Steel and FRP Re-Bars

2006 ◽  
Vol 306-308 ◽  
pp. 1367-1372
Author(s):  
Jeong Hun Nam ◽  
Seung Sik Lee ◽  
Soon Jong Yoon ◽  
Won Sup Jang ◽  
S.K. Cho
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Structural Element ◽  
Steel Reinforced Concrete ◽  
Frp Composite ◽  
Theoretical Predictions ◽  
Coated Surface

FRP composite materials are widely applicable in the construction industries as a load-bearing structural element or a reinforcing and/or repairing materials for the concrete. In this paper, we presented the flexural behavior of steel reinforced concrete beams reinforced with FRP re-bars manufactured by different fibers but the same vinylester resin. Experimental investigation pertaining to the load-deflection and load-strain characteristics of steel reinforced concrete beams reinforced with FRP re-bars with garnet coated surface is presented and the theoretical prediction is also conducted. In the investigation, the effects of FRP re-bar reinforcement in addition to the steel reinforcement are estimated. The experimental results are compared with theoretical predictions. Good agreements are observed.

Experimental Studies on Strengthening of Reinforced Concrete Beams Using Ferrocement Wraps for Energy Efficiency

2016 ◽  
Vol 692 ◽  
pp. 38-44
Author(s):  
M.M. Vijayalakshmi ◽  
A. Vijayalakshmi
Keyword(s):  
Reinforced Concrete ◽  
Construction Industry ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Result ◽  
Construction Technology ◽  
Structural Element ◽  
Concrete Material ◽  
Code Of Practice

Construction industry is a major consumer of energy and resources, which has an impact on the environment. Ferrocement construction technology is becoming popular throughout the world. Ferrocement is a thin element used for building construction and also for retrofitting, because it can be applied quickly on the surface of the damaged structural element without the requirement of any special bonding material. It requires less skilled labour when compared to other retrofitting solutions existing at present. This paper deals with the study of performance of ferrocement wrapping in strengthening of RC beams. The ferrocement construction has an edge over the conventional reinforced concrete material because of its lighter weight, ease of construction, low self-weight, thinner section and high tensile strength which makes it a favorable material for prefabrication also. Experimental work is carried out for beam having dimensions 250mm x 125mm x 3000mm, to investigate the behaviour of reinforced concrete beams retrofitted with ferrocement to increase the strength of beams in both shear and flexure. Three reinforced concrete beams are casted in order to study different parameters such as strength, stiffness, stability and ductility. M25 grade concrete and Fe 415 steel is used. Beam is designed as per IS : 456-2000 code of practice. The mix design is done as per code IS : 10262-2000. The experimental result concludes that ferrocement technology is the best solution in strengthening of Reinforced Concrete beams to meet the demand in an efficient and economical way for sustainable development.

Shear Capacity Research on Transversely Reinforced Concrete Beams

2015 ◽  
Vol 744-746 ◽  
pp. 283-287
Author(s):  
Can Liu
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Great Influence ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Force Level ◽  
Prestressed Concrete Beam ◽  
Prestressing Force

Inner transverse prestressed bars were used to enhance the shear capacity of concrete beams in this paper, which can be used in transformer beams to reduce the sectional size. Two transversely prestressed one ordinary concrete beams were tested and calculated by finite element method, and the following conclusions can be drawn: (a)The shear capacity of transversely prestressed concrete beam increase rapidly with the increase of the prestressing force level, which means that prestressing force level has a great influence on the shear capacity of transversely prestressed concrete beam. (b) The transverse prestressing bars can efficiently enhance the anti-crack performance of the reinforced concrete beams.

scholarly journals Vibrations of cracked reinforced and prestressed concrete beams

2008 ◽  
Vol 6 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Zsolt Huszár
Keyword(s):  
Cross Sections ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Bending Moment ◽  
Reinforced Concrete Beams ◽  
Bending Rigidity ◽  
Elastic Range ◽  
Non Linear ◽  
Linear Vibrations ◽  
Prestressed Beams

The dynamic behaviour of bent reinforced concrete beams in elastic range is significantly influenced by cracks caused by former loads. Considering this fact a more accurate calculation of the eigenfrequencies of the beams is available. Experiments have shown that the features of vibration differ from the results obtained by the well-known linear model, if cracked zones exist. The cause of this phenomenon is that the bending rigidity of the cross-sections in the cracked range depends on the sign of the actual bending moment. Therefore the vibration shows non-linear characteristics in the elastic range as well. The dynamic behavior of bent prestressed concrete beams is similar. The dynamic characteristics of prestressed beams besides cracks is influenced also by the intensity and eccentricity of the axial force. For a detailed investigation of the problem, experiments and non-linear analysis were performed. On the basis of these the virtual eigenfrequencies of the non-linear vibrations were determined.

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