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Article
Publication date: 13 March 2020

Static field test on flexural behavior of reinforced concrete T-beam bridge strengthened with MPC-PSWR

Hongshuai Gao and Quansheng Sun

With the rapid development of transportation and the continuous increase of traffic volume and load level, some bridges cannot meet the use requirements, and the demand…

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Abstract

Purpose

With the rapid development of transportation and the continuous increase of traffic volume and load level, some bridges cannot meet the use requirements, and the demand for bridge strengthening is growing. Furthermore, bridges are affected by factors such as structure and external environment. With the increase of service time, the deterioration of bridges is also increasing. In order to avoid the waste caused by demolition and reconstruction, it is necessary to strengthen the bridge accurately and effectively to improve the bearing capacity and durability, eliminate the hidden dangers, and ensure the normal operation of the bridge. It is of great significance to study the strengthening methods. Compared with traditional strengthening methods, the advantages of using new materials and new technology to strengthen bridges are more obvious. This paper introduces a new method for bridge active strengthening, called modified polyurethane cement with prestressed steel wire rope (MPC-PSWR).

Design/methodology/approach

Relying on the actual bridge strengthening project, five T-beams of the superstructure of the bridge are taken as the research object, and the T-beams before and after strengthening are evaluated, calculated, and analyzed by finite element simulation and field load test. By comparing the numerical simulation and load test data, the strengthening effect of modified polyurethane cement with prestressed steel wire rope on stiffness, strength, and bearing capacity is verified, which proves that the strengthening effect of MPC-PSWR is effective for strengthening.

Findings

MPC-PSWR can effectively reduce deflection, cracks, and strain, thereby significantly improving the flexural capacity of existing bridges. Under the design load, the deflection, crack width, and stress of the strengthened beams decrease in varying degrees. The overall performance of the beams strengthened by MPC-PSWR has been improved, and the flexural performance meets the requirements of the code.

Originality/value

MPC-PSWR is an innovative bridge-strengthening method. Through the analysis of its MPC-PSWR effect, the MPC-PSWR method with reference to significance for the design and construction of similar bridges is put forward.

Details

International Journal of Structural Integrity, vol. 11 no. 3
Type: Research Article
DOI: https://doi.org/10.1108/IJSI-09-2019-0089
ISSN: 1757-9864

Keywords

  • Strengthening
  • Modified polyurethane cement (MPC)
  • Static loading test

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Article
Publication date: 12 June 2017

A study on different techniques of restoration of fire damaged reinforced concrete flexural members

Danie Roy Anasco Bastin, Umesh Kumar Sharma and Pradeep Bhargava

The main aim of this research was to investigate the effectiveness of various strengthening techniques in restoring the structural performance of reinforced concrete (RC…

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Abstract

Purpose

The main aim of this research was to investigate the effectiveness of various strengthening techniques in restoring the structural performance of reinforced concrete (RC) beams damaged by elevated temperatures.

Design/methodology/approach

Three different strengthening techniques, namely, high-strength fibre reinforced concrete (HSFRC), ferrocement (FC) jacketing and externally bonded fibre-reinforced polymer (FRP) were used. Series of RC beams were casted, heated, strengthened and tested to investigate the influence of various variables. The variables of the study were type of strengthening and level of heat damage.

Findings

Externally bonded FRP was found to be the best among the various techniques, especially with respect to strength and stiffness restoration. On the contrary, the FRP strengthening was not that effective in restoring the energy absorption capacity of beams compared to HSFRC and FC techniques of strengthening. The chosen strengthening techniques were able to restore the failure mode of beams to flexural failure, which was found to have changed to shear failure in case of heated unstrenghthened beams.

Originality/value

This research program has contributed to the fundamental understanding of designing post fire retrofit solutions for RC beams.

Details

Journal of Structural Fire Engineering, vol. 8 no. 2
Type: Research Article
DOI: https://doi.org/10.1108/JSFE-03-2017-0026
ISSN: 2040-2317

Keywords

  • Ductility
  • Stiffness
  • Concrete beams
  • Flexural strength
  • Heat damage
  • Strengthening

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Article
Publication date: 1 October 2018

Experimental study on prestressed concrete hollow slabs in service strengthened with prestressed CFRP plates

Jiawei Wang, Yanmin Jia, Guanhua Zhang, Jigang Han and Jinliang Liu

Most existing studies are confined to model beam tests, which cannot reflect the actual strengthening effects provided by prestressed carbon-fiber-reinforced polymer…

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Abstract

Purpose

Most existing studies are confined to model beam tests, which cannot reflect the actual strengthening effects provided by prestressed carbon-fiber-reinforced polymer (CFRP) plates to existing bridges. Hence, the actual capacity for strengthening existing bridges with prestressed CFRP plates is becoming an important concern for researchers. The paper aims to discuss these issues.

Design/methodology/approach

Static load tests of in-service prestressed concrete hollow slabs before and after strengthening are conducted. Based on the results of the tests, the failure characteristics, failure mechanism and bending performance of the slabs are compared and analyzed. Nonlinear finite element method is also used to calculate the flexural strength of the strengthened beams prestressed with CFRP plates.

Findings

Test results show that prestressed CFRP plate strengthening technology changes the failure mode of hollow slabs, delays the development of deflection and cracks, raises cracking and ultimate load-carrying capacity and remarkably improves mechanical behavior of the slab. In addition, the nonlinear finite element analyses are in good agreement with the test results.

Originality/value

Strengthening with prestressed CFRP plates has greater advantages compared to traditional CFRP plate strengthening technology and improves active material utilization. The presented finite element method can be applied in the flexural response calculations of strengthened beams prestressed with CFRP plates. The research results provide technical basis for maintenance and reinforcement design of existing bridges.

Details

International Journal of Structural Integrity, vol. 9 no. 5
Type: Research Article
DOI: https://doi.org/10.1108/IJSI-08-2017-0049
ISSN: 1757-9864

Keywords

  • Finite element analysis
  • Prestressed CFRP plate
  • Prestressed concrete hollow slab
  • Static load test
  • Strengthening

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Article
Publication date: 1 October 2001

Strengthening of concrete structures with FRP sheets and plates

R.V. Balendran, T.M. Rana and A. Nadeem

Presents an overview and discusses the applications of fibre reinforced polymer (FRP) sheets and plates in the strengthening of concrete structures. An insight may be…

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Abstract

Presents an overview and discusses the applications of fibre reinforced polymer (FRP) sheets and plates in the strengthening of concrete structures. An insight may be obtained from the discussions made to enhance the use of these techniques for productive use. In addition, selected case studies have been furnished where FRP materials have been used for repairing/retrofitting, emphasizing the application of different types of FRP materials in strengthening concrete structures. Concludes that the use of FRP material is rapidly gaining pace and replacing the traditional steel or metal based materials due to its enhanced properties and cost effectiveness.

Details

Structural Survey, vol. 19 no. 4
Type: Research Article
DOI: https://doi.org/10.1108/02630800110406685
ISSN: 0263-080X

Keywords

  • Buildings
  • Reinforcement
  • Bonds
  • Ductility

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Article
Publication date: 5 August 2019

Effectiveness of CFRP composites on compression flange of structural I-beam

Prashant Rangrao Jagtap and Sachin M. Pore

This study aims to use carbon fiber-reinforced polymer (CFRP) laminates to strengthen the compression flange of structural I-beam so as to avoid local failure of…

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Abstract

Purpose

This study aims to use carbon fiber-reinforced polymer (CFRP) laminates to strengthen the compression flange of structural I-beam so as to avoid local failure of compression flange and to take a load to its full capacity. Light weight beam (LB) 100 at 5.1 kg/m and LB 115 at 8.1 kg/m are used for this purpose. The compression flange of a beam is well prepared to ensure a rust-free surface so as to achieve proper bonding between the flange and fiber sheet to avoid de-bonding at the time of testing. A flange of the beam is strengthened using CFRP sheets applied to it with the help of adhesive. The beam with CFRP is cured in air for 48 h before testing. Experiments are performed in a loading frame of 100 T capacity. Results show that the load carrying capacity of the strengthened beam increased by 25-30 per cent compared to the control beam (non-strengthened), and the local failure of the compression flange due to the applied load is totally avoided. The elastic behavior of the strengthened beam is also increased compared to the non-strengthened beam, which gives a higher yield point.

Design/methodology/approach

Different methods exist for strengthening various structures. Use of CFRP appears to be an excellent solution. Vast research has been conducted on the use of CFRP for strengthening and retrofitting of steel structures. The load carrying capacities of steel beams can be increased by strengthening their compression flange by using CFRP and avoiding the local failure of beams at early stages.

Findings

The load carrying capacity of a beam strengthened with CFRP increased by 25-30 per cent compared to the non-strengthened beam. In addition, the elastic behavior of the strengthened beam is also improved.

Originality/value

The compression flange of the steel beam is strengthened using different layers of CFRP strips to avoid the local failure, and its deflection is observed using linear variable deformation transducer.

Details

Journal of Engineering, Design and Technology, vol. 17 no. 4
Type: Research Article
DOI: https://doi.org/10.1108/JEDT-09-2018-0155
ISSN: 1726-0531

Keywords

  • CFRP
  • Deflection
  • Strengthening
  • I-Beam

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Article
Publication date: 10 September 2018

Performance comparison of fiber sheet strengthened RC beams bonded with geopolymer and epoxy resin under ambient and fire conditions

Hai Yan Zhang, Hao Ran Lv, Venkatesh Kodur and Shu Liang Qi

This paper aims to present performance comparison of fiber sheet-strengthened reinforced concrete (RC) beams bonded with geopolymer and epoxy resin under ambient and fire…

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Abstract

Purpose

This paper aims to present performance comparison of fiber sheet-strengthened reinforced concrete (RC) beams bonded with geopolymer and epoxy resin under ambient and fire conditions.

Design/methodology/approach

This study presents experimental results of bending tests at ambient temperature and fire resistance tests on two control beams and eight fiber sheet-strengthened RC beams. The test variables include fiber sheet type (carbon fiber [CF] and basalt fiber [BF] sheet), number of layers of fiber sheet (one and two layers) and adhesive agent type (geopolymers and epoxy resin). Data generated from these tests were used to evaluate and compare the strengthening effectiveness of CF-reinforced polymer (CFRP) and CF-reinforced geopolymer (CFRG) at ambient temperature and under fire exposure conditions.

Findings

Test results clearly show that the CFRG system can provide good strengthening effectiveness on RC beams at ambient temperature, as the CFRP system, owing to excellent bond properties of geopolymers. Although geopolymers possess better bonding properties at high temperature than organic matrix, the strengthened beams bonded with geopolymer do not exhibit better fire resistance than that those bonded with epoxy resin, owing to early falling-off of fire insulation. Thus, in CFRG-strengthened beams, relevant measures are to be taken to minimize falling-off of fire insulation to achieve good fire resistance.

Originality/value

The presented results are from unique fire tests and provide valuable insight (and information) on the performance of fiber sheet-strengthened RC beams bonded with geopolymer and epoxy resin under ambient and fire conditions.

Details

Journal of Structural Fire Engineering, vol. 9 no. 3
Type: Research Article
DOI: https://doi.org/10.1108/JSFE-01-2017-0023
ISSN: 2040-2317

Keywords

  • Epoxy resin
  • Fire resistance test
  • Bending tests
  • Concrete beam
  • FRP strengthening
  • Geopolymer

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Article
Publication date: 16 April 2019

Effectiveness of seismic strengthening to repeated earthquakes in historic urban contexts: Norcia 2016

Valentina Putrino and Dina D’Ayala

The purpose of this paper is to discuss the dynamics of the evolution of damage to the residential buildings within the city walls of Norcia during the six-month seismic…

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Abstract

Purpose

The purpose of this paper is to discuss the dynamics of the evolution of damage to the residential buildings within the city walls of Norcia during the six-month seismic swarm that hit Central Italy in the period 24th August 2016 to end of January 2019. This is accomplished by comparing the damage recorded by the Italian Civil Protection usability form (AEDES form) during this period after each event.

Design/methodology/approach

First, these outputs are compared with a qualitative assessment conducted by means of omnidirectional camera (ODC) imagery collected on site by the authors, to explore the ability of this technology to support post-earthquake damage assessment. The damage level attributed with these two techniques is then further compared with the output of the analytical vulnerability assessment method FaMIVE, which allows to correlate damage to vulnerability. Specifically, the objective is to investigate the efficacy and performance of historic and recent strengthening interventions.

Findings

Results show that there is a good correspondence between AeDES and ODC assessments for low to medium damage grades (DG). Discrepancies in higher DGs are discussed in light of the different levels of information that can be recorded by using the two tools. The efficacy of strengthening is also well captured by the FaMIVE method. The procedure estimates a decrease of almost 40, 25 and 20 per cent of the total number of buildings failing out-of-plane, respectively, for the three seismic events considered, when restraining elements are in action.

Research limitations/implications

The analysis conducted in this work make use of deterministic values of Norcia’s masonry fabric characteristics that have been found in literature, thus implying that neither the probabilistic aspects nor the related uncertainties have been properly investigated and addressed. However, this limitation is to be considered within the more general context of the legislation for the preservation of historic buildings which limits substantially any type of semi-destructive tests, hence limiting the reliability of the values available in literature. This in turn affects the decisions informing the design and implementation of strengthening interventions which can be confidently considered reliable and effective.

Originality/value

The paper addresses for the first time a systematic investigation of damage progression in historic masonry structures, part of urban aggregates in heritage cities. The current urban fabric is discussed in view of historic building codes as the basis for determining the present seismic vulnerability of the historic city centre of Norcia. The study provides new data sets for the city of Norcia and develops a statistical correlation between cumulative damage and analytical vulnerability functions for heritage buildings exposed to a swarm of earthquakes. The analytical assessment of the effect of historic strengthening is totally novel.

Details

Disaster Prevention and Management: An International Journal, vol. 29 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/DPM-07-2018-0230
ISSN: 0965-3562

Keywords

  • Cumulative damage
  • Heritage urban centres
  • Vulnerability assessment
  • Strengthening measures

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Article
Publication date: 17 June 2020

Experimental study on shear behavior of hollow slab beam strengthened with pasting steel plates

Jiawei Wang, Jinliang Liu, Guanhua Zhang and Jigang Han

Considering the “size effect” and the properties degradation of building materials on the strengthened engineering, in this paper, the technology of pasting steel plate…

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Abstract

Purpose

Considering the “size effect” and the properties degradation of building materials on the strengthened engineering, in this paper, the technology of pasting steel plate was adopted to shear strengthen a 16 m prestressed concrete hollow slab, which had serviced 20 years in cold regions. The shear properties of shear strengthen beams are analyzed.

Design/methodology/approach

Shear loading test of the shear strengthened beam and the contrast beam was conducted. Then the mechanical characteristics, failure mechanism, the mechanical response and shear capacity of shear strengthened beam and contrast beam had been discussed.

Findings

The failure mode of shear strengthened beam and contrast beam was shear compression failure, and the bond failure between concrete and prestressed reinforcement happened in both of test beams. The shear strengthening method of pasting steel plate can effectively improve the mechanical response for the shear strengthened beam. Compared with the contrast beam, the cracking load and failure shear capacity for the shear strengthened beam can be effectively increased by 12.2 and 27.6%, respectively.

Originality/value

The research results can be a reference for the detection and evaluation of shear strengthened bridges, which are strengthened by pasting steel plate. Engineers can refer to the shear strengthening method in this paper to strengthen the existing bridge, which can guarantee the safety of shear strengthened bridges.

Details

International Journal of Structural Integrity, vol. ahead-of-print no. ahead-of-print
Type: Research Article
DOI: https://doi.org/10.1108/IJSI-04-2020-0038
ISSN: 1757-9864

Keywords

  • In-service prestressed concrete bridge
  • Shear strengthened technology
  • Pasting steel plate
  • Shear compression failure
  • Shear capacity

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Article
Publication date: 12 June 2017

The experimental behavior of CFRP-strengthened reinforced concrete slabs with fire protection systems subjected to standard fire exposure

Saeed Bakhtiyari, Arsalan Kalali, Leila Taghi Akbari and Farhang Farahbod

This paper aims to evaluate fire resistance of carbon fiber-reinforced polymer (CFRP)-strengthened concrete slabs in two forms of unprotected and protected against fire.

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Abstract

Purpose

This paper aims to evaluate fire resistance of carbon fiber-reinforced polymer (CFRP)-strengthened concrete slabs in two forms of unprotected and protected against fire.

Design/methodology/approach

To achieve the objective, an unstrengthened and two CFRP-strengthened concrete slabs were first subjected to increasing gravity loading until failure. Subsequently, the unstrengthened concrete slab was placed on a furnace and was subjected to a constant service gravity load and then, the temperature of the furnace was increased according to a standard temperature–time curve until the failure of the slab occurred. This slab was strengthened by CFRP with two different amounts and then, in two cases of unprotected and protected against fire, was tested in accordance with the aforementioned method.

Findings

The gravity test results revealed that CFRP strips bonded to concrete slabs increased the load-bearing capacity considerably. So, this method can be suitable for flexural strengthening of concrete slabs. The fire test results showed that because of more load-bearing capacity and subsequently increase in service gravity load, the strengthened concrete slab failed in a short time due to the lack of CFRP resistance against fire. By contrast, the protected specimens resisted the fire in a considerable time. In addition, it was revealed that details of fire protective coating had an important effect on fire resistance duration.

Originality/value

It is notable that in the literature, there is a lack of data on the fire endurance of fiber-reinforced polymer-strengthened concrete slabs alone without any fire protection system. Furthermore, the applicability and effectiveness of a new kind of spray mineral fire protective coatings was evaluated.

Details

International Journal of Disaster Resilience in the Built Environment, vol. 8 no. 3
Type: Research Article
DOI: https://doi.org/10.1108/IJDRBE-07-2016-0029
ISSN: 1759-5908

Keywords

  • FRP
  • Fire resistance
  • Strengthening
  • Fire protective coating
  • Loading
  • Reinforced concrete slab

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Article
Publication date: 14 May 2018

Strengthening school management committees: a framework for process and outcome

Nauman Adil, Zaki Rashidi and Reema Frooghi

The purpose of this paper is to analyze the existing mechanism of school management committees (SMCs) and to propose an improved framework for strengthening its process…

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Abstract

Purpose

The purpose of this paper is to analyze the existing mechanism of school management committees (SMCs) and to propose an improved framework for strengthening its process and outcomes. In 2005, the Education and Literacy department, Government of Sindh decentralizes the administrative and operational authorities to school level in the form of SMCs. These committees have been vested with several roles and responsibilities in accordance with the objective of SMCs set in by government in assistance with different international donor agencies.

Design/methodology/approach

The purposively selected respondent that includes 35 stakeholders among which 25 stakeholders has been interviewed individually while other ten has been interviewed in the form of two focused groups consisting of five members each. The findings based on the interviews are analyzed using the thematic analysis. This study analyzes the formation of SMCs, roles and responsibilities of members, Allocation SMC funds and its utilization methods. The study includes the challenges faced by these committees in school administration and operations with their recommendations for overcoming such challenges. Some common challenges include limited financial resources, interference of landlords and potential people of the community, limited administrative authorities and lack of interest of government toward government schools.

Findings

The recommendations have been categorized into three broad themes: strengthening of mechanism, strengthening through functions, roles and responsibilities and revising SMC fund allocation and its utilization.

Originality/value

The study proposed an improved framework for strengthening the process and outcomes of SMC.

Details

International Journal of Educational Management, vol. 32 no. 4
Type: Research Article
DOI: https://doi.org/10.1108/IJEM-03-2017-0072
ISSN: 0951-354X

Keywords

  • Community participation
  • Mechanism
  • SMC
  • School management committee

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