Experimental study on condition assessment of reinforced concrete structure using a dynamics response approach

2014 ◽  
Vol 32 (2) ◽  
pp. 89-101
Author(s):  
Chun Pong Sing ◽  
P.E.D. Love ◽  
P.R. Davis
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequency ◽  
Time Domain ◽  
Damping Ratio ◽  
Content Type ◽  
Rc Structures ◽  
Random Decrement ◽  
Rc Structure ◽  
Non Linear ◽  
Linear Damping

Purpose – Condition assessment on reinforced concrete (RC) structures is one of the critical issues as a result of structure degradation due to aging in many developed countries. The purpose of this paper is to examine the sensitivity and reliability of the conventional dynamic response approaches, which are currently applied in the RC structures. The key indicators include: natural frequency and damping ratio. To deal with the non-linear characteristics of RC, the concept of random decrement is applied to analyze time domain data and a non-linear damping curve could be constructed to reflect the condition of RC structure. Design/methodology/approach – A full-scale RC structure was tested under ambient vibration and the impact from a rubber hammer. Time history data were collected to analyze dynamics parameters such as natural frequency and damping ratio. Findings – The research demonstrated that the measured natural frequency is not a good indicator for integrity assessment. Similarly, it was revealed that the traditional theory of viscous damping performed poorly for the RC with non-linear characteristics. To address this problem, a non-linear curve is constructed using random decrement and it can be used to retrieve the condition of the RC structure in a scientific manner. Originality/value – The time domain analysis using random decrement can be used to construct a non-linear damping curve. The results from this study revealed that the damage of structure can be reflected from the changes in the damping curves. The non-linear damping curve is a powerful tool for assessing the health condition of RC structures in terms of sensitivity and reliability.

Damage assessment of reinforced concrete flat slabs through modal tests using impact excitation

2019 ◽  
Vol 10 (2) ◽  
pp. 265-275 ◽  
Author(s):  
Gabriel S. Ferreira ◽  
Tulio O. Guedes ◽  
Lucas F. Melo ◽  
Márcio S. Gonçalves ◽  
Roberto Pimentel
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequency ◽  
Damage Assessment ◽  
Crack Opening ◽  
Impact Excitation ◽  
Content Type ◽  
Rc Structures ◽  
Fundamental Natural Frequency ◽  
Cracking Pattern ◽  
The Impact

Purpose In reinforced concrete (RC) structures, an evidence of damage is the presence of cracking. In order to evaluate the effect of damage on cracking pattern and natural frequency in RC slabs, two of such structures with different dimensions and reinforcement ratios were tested, in which cracks were induced through application of static load, followed by modal tests using impact excitation. The paper aims to discuss this issue. Design/methodology/approach The gradient of the fundamental natural frequency along the decay, the crack opening rate and also a global damage index based on changes of the fundamental natural frequency were evaluated. Findings The behaviour of the aforementioned gradient was distinct for both slabs, increasing monotonically with the cracking level for the slab with lowest reinforcement ratio, and increasing until 33 per cent of the collapse load and then decreasing afterwards for the slab with the highest ratio. Changes of the gradient were consistent with changes of the crack opening rate. Both results of gradient changes and cracking pattern brought evidence that the balance between open (old) and breathing (new) cracks differed between the slabs, and may be responsible for such differences. Originality/value Damage assessment in RC structures using vibration tests is mostly concentrated on beams. In this work, an advance is made by investigating slabs. The lack of a unique pattern of changes of the gradient implies that its absolute value is not generally suitable for the association with the damage level. However, the impact tests can be effectively used to detect early damage on slabs using this proposed parameter.

scholarly journals Effects of Tension Reinforcement Ratio on Ductility of Mid-Rise Reinforced Concrete Structures

2018 ◽  
Vol 1 (1) ◽  
pp. 702-708
Author(s):  
Onur Onat ◽  
Burak Yön
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Concrete Structures ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Beam Elements ◽  
First Case ◽  
Rc Structure ◽  
Determine Effect

Failure mode of reinforced concrete (RC) structures are classified according to tension reinforcement ratio of beam elements. To determine effect of tension reinforcement ratio on performance of RC structure, two planar RC structure were selected. One of them is 5 stories other of them is 7 stories. Two different concrete class, C20 and C25, were considered for analysis. Three tension reinforcement combinations were considered, three different tension reinforcement ratios were used. First case is the ratio of the tension reinforcement is lower than that of the compression reinforcement, second case is the ratio of the tension reinforcement is equal to the ratio of the compression reinforcement and third case is the ratio of the tensile reinforcement is higher than the compression reinforcement.

Enhancement of vibration characteristics in filament wound FRP composite shafts using nitinol wires

2018 ◽  
Vol 47 (5) ◽  
pp. 377-385 ◽  
Author(s):  
Kannan Murugesan ◽  
Kalaichelvan K. ◽  
M.P. Jenarthanan ◽  
Sornakumar T.
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Filament Winding ◽  
Fiber Reinforced ◽  
Content Type ◽  
Fiber Reinforced Plastic ◽  
Damping Characteristics ◽  
Filament Wound ◽  
Reinforced Plastic ◽  
Hollow Shafts

Purpose The purpose of this paper is to investigate the use of embedded Shape Memory Alloy (SMA) nitinol wire for the enhancement of vibration and damping characteristics of filament-wound fiber-reinforced plastic composite hollow shafts. Design/methodology/approach The plain Glass Fiber-Reinforced Plastic (GFRP) and plain Carbon Fiber-Reinforced Plastic (CFRP) hollow shafts were manufactured by filament winding technique. Experimental modal analysis was conducted for plain hollow shafts of C1045 steel, GFRP and CFRP by subjecting them to flexural vibrations as per ASTM standard C747, with both ends clamped (C-C) end condition to investigate their vibration and damping behavior in terms of first natural frequency, damping time and damping ratio. Nitinol wires pre-stressed at various pre-strains (2, 4 and 6 per cent) were embedded with CFRP hollow shafts following same manufacturing technique, and similar experimental modal analysis was carried out by activating nitinol wires. The first natural frequencies of all the shaft materials were also predicted theoretically and compared with experimental measurements. Findings Among the three materials C1045 steel, plain GFRP and plain CFRP, the vibration and damping behavior were found to be the best for plain CFRP. Hence, CFRP shafts were considered for further improvement by embedding nitinol wires at pre-stressed condition. For CFRP shafts embedded with nitinol wires, the damping time decreased; and damping ratio and first natural frequency increased with increase in percentage of pre-strain. In comparison with plain CFRP, 7 per cent increase in first natural frequency and 100 per cent increase in damping ratio were observed for nitinol embedded CFRP shafts with 6 per cent pre-strain. Theoretical predictions of the first natural frequencies agree well with the experimental results for all the shaft materials. Originality/value The effect of nitinol on vibration and damping characteristics of filament wound hollow CFRP composite shafts with different pre-strains has not been studied extensively by the previous researchers. This paper addresses the effect of embedded nitinol wires pre-stressed at three varied pre-strains, that is, 2, 4 and 6 per cent on the vibration and damping characteristics of composite hollow CFRP shafts manufactured by filament winding technique.

Corrosion effects on seismic capacity of reinforced concrete structures

2019 ◽  
Vol 37 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Antonio Bossio ◽  
Francesco Fabbrocino ◽  
Tullio Monetta ◽  
Gian Piero Lignola ◽  
Andrea Prota ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Seismic Behavior ◽  
Concrete Cover ◽  
Residual Service Life ◽  
Seismic Capacity ◽  
Rc Structures ◽  
Behavior Simulation ◽  
Cover Cracking ◽  
Rc Structure

AbstractRecently, corrosion prevention and monitoring of reinforced concrete (RC) structures became an important issue for seismic assessment of such kind of structures. Therefore, it is important to develop adequate models to represent material degradation into seismic behavior simulation of RC structures. Because of its effects, corrosion represents the most important form of degradation for materials and structures, both for wide diffusion and the amount of danger it presents. To understand the corrosion process is critical in order to design RC structures that are able to guarantee the required service life and in order to understand the residual service life and strength of an existing structure. The seismic behavior of a corroded framed RC structure is analyzed by means of push-over analyses, which allow understanding the development of the global behavior of the structure. Three different degrees of corrosion penetration were simulated, by means of the reduction of bars and stirrups’ diameters and concrete cover cracking and spalling, and three different configurations of corrosion, depending on the number of corroded frames and sides of the structural elements.

scholarly journals Heating Temperature Prediction of Concrete Structure Damaged by Fire Using a Bayesian Approach

2020 ◽  
Vol 12 (10) ◽  
pp. 4225
Author(s):  
Hae-Chang Cho ◽  
Sun-Jin Han ◽  
Inwook Heo ◽  
Hyun Kang ◽  
Won-Hee Kang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
Model Development ◽  
Estimation Model ◽  
Temperature Estimation ◽  
Rc Structures ◽  
Material Development ◽  
Rc Structure ◽  
Eurocode 2

A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 °C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application.

On a mixed time integration procedure for non-linear structural dynamics

2015 ◽  
Vol 32 (2) ◽  
pp. 329-369 ◽  
Author(s):  
Mário Rui Tiago Arruda ◽  
Dragos Ionut Moldovan
Keyword(s):  
Time Domain ◽  
Equations Of Motion ◽  
Time Integration ◽  
Linear Analysis ◽  
Integration Scheme ◽  
Decomposition Technique ◽  
Modal Decomposition ◽  
Content Type ◽  
Non Linear ◽  
The Time Domain

Purpose – The purpose of this paper is to report the implementation of an alternative time integration procedure for the dynamic non-linear analysis of structures. Design/methodology/approach – The time integration algorithm discussed in this work corresponds to a spectral decomposition technique implemented in the time domain. As in the case of the modal decomposition in space, the numerical efficiency of the resulting integration scheme depends on the possibility of uncoupling the equations of motion. This is achieved by solving an eigenvalue problem in the time domain that only depends on the approximation basis being implemented. Complete sets of orthogonal Legendre polynomials are used to define the time approximation basis required by the model. Findings – A classical example with known analytical solution is presented to validate the model, in linear and non-linear analysis. The efficiency of the numerical technique is assessed. Comparisons are made with the classical Newmark method applied to the solution of both linear and non-linear dynamics. The mixed time integration technique presents some interesting features making very attractive its application to the analysis of non-linear dynamic systems. It corresponds in essence to a modal decomposition technique implemented in the time domain. As in the case of the modal decomposition in space, the numerical efficiency of the resulting integration scheme depends on the possibility of uncoupling the equations of motion. Originality/value – One of the main advantages of this technique is the possibility of considering relatively large time step increments which enhances the computational efficiency of the numerical procedure. Due to its characteristics, this method is well suited to parallel processing, one of the features that have to be conveniently explored in the near future.

Member and structural fragility of reinforced concrete structure under fire

2020 ◽  
Vol 11 (4) ◽  
pp. 409-435 ◽  
Author(s):  
Ranjit Kumar Chaudhary ◽  
Tathagata Roy ◽  
Vasant Matsagar
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Vulnerability Assessment ◽  
Fire Hazard ◽  
Fe Analysis ◽  
Content Type ◽  
Rc Structures ◽  
Structural Fire ◽  
Structural Fragility ◽  
Safety And Reliability

Purpose Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein effect of uncertainties influencing the fire resistance of structures are not explicitly considered. In this context, a probabilistic framework is presented to investigate the vulnerability of a reinforced concrete (RC) members and structure under fire loading scenario. Design/methodology/approach The RC structures exposed to fire are modeled in a finite element (FE) platform incorporating material and geometric nonlinearity, in which the transient thermo-mechanical analysis is carried out by suitably incorporating the temperature variation of thermal and mechanical properties of both concrete and steel rebar. The stochasticity in the system is considered in structural resistance, thermal and fire model parameters, and the subsequent fragility curves are developed considering threshold limit state of deflection. Findings The fire resistance of RC structure is reported to be significantly lower in comparison to the RC members, thereby illustrating the current prescriptive design approaches based on studies of structural member behavior to be crucial from a safety and reliability point of view. Practical implications The framework developed for the vulnerability assessment of RC structures under fire hazard through FE analysis can be effectively used to estimate the structural fire resistance for other similar structure to enhance safety and reliability of structures under such extreme threats. Originality/value The paper proposes a novel methodology for vulnerability assessment of three-dimensional RC structures under fire hazard through FE analysis and provides comparison of the structural fragility with fragility developed for structural members. Moreover, the research emphasizes to assume 3D behavior of the structure rather than the approximate 2D behavior.

scholarly journals Finite Element Analysis of Corrosion and Bond-Slip

2021 ◽  
Author(s):  
Yan Lan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforcement Corrosion ◽  
Element Analysis ◽  
Rc Structures ◽  
Bond Slip ◽  
Linear Finite Element ◽  
Rc Structure ◽  
Non Linear ◽  
Bond Mechanism

Although reinforced concrete (RC) has an important advantage that it has virtue durability against an environmental attack, especially the resistance of corrosion of embedded reinforcements, due to the high alkalinity nature of concrete property, unfortunately, the problems of reinforcement corrosion still exist in many reinforced concrete structures. It has brought out many questions on the safety and serviceability of these corroded RC structures. Thus, it needs more effective approach for structural performance evaluation of the corroded structures. The residual capacity of the corroded reinforcement was determined through the evaluation of the volume increase of reinforcing steel and concrete crack propagation. The final determination of the service life of concrete structures was made based on the above evaluation results. Also, the effects of reinforcement corrosion on structural behaviours of RC members are investigated so that the reliable evaluation of structural performances of corroded RC members can be achieved by finite element method (FEM). The corrosion attack penetration has been given as a function of the time as input in the analyses. The load of corrosion applied inside the structural members can be modelled by the displacement around the circumferential surface between the reinforcing bars and concrete. The reduction of capability of the structures is determined from the corrosion level in the service years. Another complex phenomenon that governs concrete behaviour is the transfer of shear force across the interface by bond mechanism between concrete and steel reinforcement. It is a fundamental to most aspects of concrete behaviour. The bond mechanism is influenced by multiple parameters, such as the strength of the surrounding structures, the occurrence of splitting cracks in the concrete and the yielding of the reinforcement. However, when RC structures are analysed using the FEM, it is quite common to assume that the bond stress depends solely on the slip between the bars and concrete. In this the research the relationship of bond slip is also studied using FEM. An analytical study based on fracture mechanics was earned out to investigate the behaviour of three different types of specimens. In recent RC research, finite element modelling techniques have been developed to quickly evaluate the physical phenomena associated with cracking and bond. The non-linear finite element program ATENA with the non-linear material models for concrete, reinforcement bar and bond-slip is used to analyse cracking propagation and bond failure process. The influence between corrosion and bond slip in RC structure is also studied. Therefore, the understanding of serviceability of RC structure is improved. It was concluded that with the increase of load and the propagation of the crack, stress redistributed in the steel- continues until the specimen is damaged. The non-linear finite element fracture analysis shows that non-linear fracture mechanics can be effectively applied to investigate concrete fracture. Also, comparisons between the analyses of crack propagation and stress redistribution obtained using the finite element analysis was in good agreement with tests found in the literature.

Fatigue damage assessment of reinforced concrete beam using average frequency and rise angle value of acoustic emission signal

2020 ◽  
Vol 11 (4) ◽  
pp. 633-643
Author(s):  
Noorsuhada Md Nor ◽  
Soffian Noor Mat Saliah ◽  
Khairul Afinawati Hashim
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Fatigue Loading ◽  
Average Frequency ◽  
Reinforced Concrete Beam ◽  
Beam Specimen ◽  
Rc Beam ◽  
Content Type ◽  
Emission Signal ◽  
Rc Structure

PurposeIn civil engineering construction, the reinforced concrete (RC) structure is generally used and exposed to fatigue loading as it is in service. The assessment of the RC structure is required to maintain the service life of the structure.Design/methodology/approachThis paper presents the behaviour of RC beam specimens under increasing maximum fatigue loading until failure. Simultaneously the acoustic emission (AE) was recorded. Twelve phases of maximum fatigue loading at Stage 1 and Stage 2 were applied to the beam with the frequency of 1 Hz and 5,000 load cycles were applied for each load phase. Two AE parameters were analysed and discussed, namely average frequency and rise angle value at CH4 and CH5.FindingsThe results found that the load and crack are closely related to the AE activities in the RC beam specimen when subjected to increasing fatigue loading.Originality/valueTo investigate the AE characteristics of RC beam specimens subjected to 12 phases of maximum fatigue loading using the average frequency and rise angle value.

Sign in / Sign up

Export Citation Format

Share Document