scholarly journals Flexural Behavior of Fire-Damaged Prefabricated RC Hollow Slabs Strengthened with CFRP versus TRM

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2556
Author(s):  
Zheng-Ang Sui ◽  
Kun Dong ◽  
Jitong Jiang ◽  
Shutong Yang ◽  
Kexu Hu
Keyword(s):  
Failure Modes ◽  
Early Stage ◽  
Load Capacity ◽  
Peak Load ◽  
Flexural Behavior ◽  
Masonry Building ◽  
Fire Exposure ◽  
Standard Fire ◽  
Four Point Bending ◽  
Strengthening Technique

In this paper, carbon fiber reinforced polymer (CFRP) and textile reinforced mortar (TRM) strengthening techniques were proposed to retrofit and strengthen fire-damaged prefabricated concrete hollow slabs. A total of six slabs, from an actual multi-story masonry building, were tested to investigate the flexural performance of reinforced concrete (RC) hollow slabs strengthened with TRM and CFRP. The investigated parameters included the strengthening method (CFRP versus TRM), the number of CFRP layers, and with or without fire exposure. One unstrengthened slab and one TRM strengthened slab served as the control specimens without fire exposure. The remaining four slabs were first exposed to ISO-834 standard fire for 1 h, and then three of them were strengthened with CFRP or TRM. Through the four-point bending tests at ambient temperature, the failure modes, load and deformation response were recorded and discussed. Both CFRP and TRM strengthening methods can significantly increase the cracking load and peak load of the fire-damaged hollow slabs, as well as the stiffness in the early stage. The prefabricated hollow slabs strengthened by CFRP have better performance in the ultimate bearing capacity, but the ductility reduced with the increase of CFRP layers. Meanwhile, the TRM strengthening technique is a suitable method for the performance improvement of fire-damaged hollow slabs, in terms of not only the load capacity, especially the cracking load, but also the flexural stiffness and deformation capacity.

scholarly journals Experimental Study on the Flexural Behavior of over Reinforced Concrete Beams Bolted with Compression Steel Plate: Part I

2020 ◽  
Vol 10 (3) ◽  
pp. 822 ◽  
Author(s):  
Shatha Alasadi ◽  
Payam Shafigh ◽  
Zainah Ibrahim
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Steel Plate ◽  
Concrete Beams ◽  
Peak Load ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Flexural Behavior ◽  
Flexural Stiffness

The purpose of this paper is to investigate the flexural behavior of over-reinforced concrete beam enhancement by bolted-compression steel plate (BCSP) with normal reinforced concrete beams under laboratory experimental condition. Three beams developed with steel plates were tested until they failed in compression compared with one beam without a steel plate. The thicknesses of the steel plates used were 6 mm, 10 mm, and 15 mm. The beams were simply supported and loaded monotonically with two-point loads. Load-deflection behaviors of the beams were observed, analyzed, and evaluated in terms of spall-off concrete loading, peak loading, displacement at mid-span, flexural stiffness (service and post-peak), and energy dissipation. The outcome of the experiment shows that the use of a steel plate can improve the failure modes of the beams and also increases the peak load and flexural stiffness. The steel development beams dissipated much higher energies with an increase in plate thicknesses than the conventional beam.

scholarly journals Effect of Combining Fiber and Textile Reinforcement on the Flexural Behavior of UHPC Plates

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Tamás Mészöly ◽  
Sandra Ofner ◽  
Norbert Randl ◽  
Zhiping Luo
Keyword(s):  
Failure Modes ◽  
Testing Machine ◽  
Fiber Reinforcement ◽  
High Strength ◽  
Image Correlation ◽  
Flexural Behavior ◽  
Textile Reinforced Concrete ◽  
Four Point Bending ◽  
Flexural Tests ◽  
Photogrammetric Measurement

A series of flexural tests were performed in order to investigate the effect of steel fiber reinforcement (SFR) in textile-reinforced concrete (TRC) plates. Some of the specimens were reinforced only with textile, some of them only with fibers, and some of them were provided with both textile and fiber reinforcement. The concrete matrix was a self-developed ultrahigh performance concrete (UHPC) mixture with a compression strength over 160 MPa. The tensile strength of the used textiles was around 1500 MPa for glass fiber textile and over 3000 MPa for carbon fiber textile. In case of fiber reinforcement, the concrete was reinforced with 2 vol% of 15 mm long and 0.2 mm diameter plain high strength steel fibers. The dimensions of the rectangular plate test specimens were 700 × 150 × 30 mm. The plate specimens were tested in a symmetric four-point bending setup with a universal testing machine. The tests were monitored using a photogrammetric measurement system with digital image correlation (DIC). The paper presents and evaluates the test results, analyses the crack patterns and crack development, and compares the failure modes. The results showed a general advantageous mechanical behavior of specimens reinforced with the combination of fibers and textiles in comparison to the specimens reinforced with only fiber or textile reinforcement.

scholarly journals Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars

2020 ◽  
Vol 6 (9) ◽  
pp. 1652-1669
Author(s):  
Phan Duy Nguyen ◽  
Vu Hiep Dang ◽  
Ngoc Anh Vu
Keyword(s):  
Failure Modes ◽  
Concrete Beams ◽  
Peak Load ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Deformation Model ◽  
Rc Beams ◽  
Linear Deformation ◽  
Crack Patterns ◽  
Steel Bars

This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel (ρg) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.

Mechanical performance of CFRP enclosed reinforced concrete beams by different shear reinforcement

2020 ◽  
pp. 136943322097478
Author(s):  
Qi Cao ◽  
Jiadong Bao ◽  
Changjun Zhou ◽  
Xianrui Lv
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Shear Reinforcement ◽  
Four Point Bending ◽  
Expansive Agent

This paper aims to study the flexural behavior of CFRP enclosed reinforced concrete beams with different shear reinforcement. Four-point bending tests were carried out on six concrete beams with different contents of steel fibers (0.5%, 1.0%, and 1.5%) as well as six beams with different stirrup spacing (100 mm, 150 mm, and 300 mm) without fiber. The effect of steel fiber (SF) content as well as stirrup spacing on flexural properties of concrete beams were investigated. Meanwhile, the effect of expansive agent on the properties of specimens was also studied. The data collected in this test include cracking load, ultimate load, mid-span deflection, strain of CFRP (Carbon fiber reinforced polymer), strain of longitudinal steel reinforcement as well as the failure modes. Test results show that both cracking loads and ultimate loads of the SF reinforced beam specimens are generally higher than those of the corresponding stirrup reinforced beam specimens. Experimental results also indicate that the addition of SF can improve the ductility and cracking resistance of specimens. This therefore demonstrates that it is feasible to replace stirrup reinforcement with SF as shear reinforcement. In addition, it exhibits a good agreement between experimental results and analytical predictions in cracking loads and ultimate loads.

Enhancing flexural capacity of RC columns through near surface mounted SMA and CFRP bars

2020 ◽  
Vol 54 (29) ◽  
pp. 4661-4676
Author(s):  
Guohua Xing ◽  
Osman E Ozbulut ◽  
Mohammed Ali Al-Dhabyani ◽  
Zhaoqun Chang ◽  
Sherif M Daghash
Keyword(s):  
Load Capacity ◽  
Peak Load ◽  
Damage Index ◽  
Flexural Behavior ◽  
Stiffness Degradation ◽  
Cumulative Energy ◽  
Rc Columns ◽  
Near Surface ◽  
Displacement Ductility ◽  
Near Surface Mounted

This study explores the flexural behavior of reinforced concrete (RC) columns strengthened with near surface mounted (NSM) shape memory alloy (SMA) bars or carbon fiber reinforced polymer (CFRP) bars. Seven RC column specimens were designed and fabricated to study the influence of different variables on the flexural response of the strengthened columns. These parameters include type of NSM reinforcement (SMA bars or CFRP bars), ratio of NSM reinforcement, and effect of CFRP jacketing. The columns were tested under cyclic lateral loading with constant axial force. The flexural behavior of each specimen was examined in terms of peak load, failure load, drift ratios, displacement ductility, stiffness degradation, energy dissipation, and seismic damage index. The experimental results indicate that strengthening of RC columns with NSM SMA or CFRP bars improves the flexural behavior of the columns through increasing the lateral load capacity, reducing the stiffness degradation and increasing the cumulative energy absorption up to failure. Further enhancement in the lateral response of RC columns was obtained by combining NSM bars and CFRP jacketing as the later provides an additional confinement to the critical sections of the test specimens.

scholarly journals Failure Modes and Mechanical Properties of Bracket Anchor Connections for Cross-Laminated-Timber

2019 ◽  
Vol 275 ◽  
pp. 01011
Author(s):  
Yinlan Shen ◽  
Johannes Schneider ◽  
Siegfried F. Stiemer ◽  
Xueyong Ren
Keyword(s):  
Failure Modes ◽  
Load Capacity ◽  
Peak Load ◽  
Force Transmission ◽  
Test Configuration ◽  
Cross Laminated Timber ◽  
State Tests ◽  
Transmission Mechanisms ◽  
Load Peak ◽  
Strength And Stiffness

The paper presents some experimental data and phenomenon on bracket anchor connections for Cross-Laminated-Timber. The goal of this research is to provide a better understanding of the seismic performance of bracket connections subjected to seismic actions and how to choose and design bracket connections for Cross-Laminated-Timber structures. Test configuration and experimental setups are illustrated in details; cyclic displacement schedules of the connections in two directions are presented considering that CLT wall has horizontal sliding in the plane and uplift at the end in quasi-state tests. Different failure modes and force transmission mechanisms of different connections under the loading protocol were analysed. And important quantities for seismic design such as strength, and stiffness, equivalent yield load, peak load and ductility of the connections are evaluated and compared among different kinds of connections; an excellent connector is revealed in ductility and load capacity by test data analysis. In addition, some suggestions to choose and design bracket anchor connections are given.

scholarly journals Experimental investigation on structural concrete masonry in fire: emphasis on the thermal behavior and residual strength

2021 ◽  
Vol 14 (4) ◽  
Author(s):  
Davi Fagundes Leal ◽  
Rafael Henrique Dupim ◽  
Jorge Munaiar Neto ◽  
Márcio Roberto Silva Corrêa
Keyword(s):  
Experimental Investigation ◽  
Thermal Behavior ◽  
High Temperatures ◽  
Room Temperature ◽  
Load Capacity ◽  
Concrete Strength ◽  
Fire Exposure ◽  
Compression Tests ◽  
Standard Fire ◽  
In Fire

abstract: This paper aims to analyze the thermal behavior and residual mechanical properties of concrete hollow-blocks structural masonry and its component materials in fire situation using experimental investigation. Compression tests were carried out on blocks, prisms and small walls at room temperature and after being exposed for 70 minutes to the ISO 834 Standard Fire. The test at high temperatures was run using a furnace powered by natural gas and instrumented with thermocouples to measure temperatures in the specimens. The influence of the initial concrete strength on masonry behavior was evaluated considering the use of blocks with different strengths at room temperature. In addition, exposure to fire was also investigated considering masonry elements with no coverings and submitted to two different fire exposure conditions: one or both sides. The results indicate a substantial loss in the masonry load capacity at high temperatures, especially in cases of fire exposure on both sides, where the residual compressive strength resulted, on average, between 20% and 27% for the blocks and approximately 14% for prisms and small walls. Its performance with fire heating up on only one face is much higher, with an average residual masonry strength equal to 46% compared to its strength at room temperature. The obtained results are also useful for evaluating masonry regarding the integrity and thermal insulation criteria, the latter achieved with little over 60 minutes of testing.

scholarly journals FLEXURAL BEHAVIOR OF RC BEAMS STRENGTHNED WITH CFRP SHEETS USING DIFFERENT STRENGTHENING TECHNIQUES

2019 ◽  
Vol 16 (1) ◽  
pp. 35
Author(s):  
Sherif El Gamal ◽  
Ali Al-Nuaimi ◽  
Abdullah Al-Saidy ◽  
Khalid Al-Shanfari
Keyword(s):  
Reference Beam ◽  
Flexural Behavior ◽  
Hybrid Technique ◽  
Rc Beams ◽  
Ultimate Capacity ◽  
Near Surface ◽  
Cfrp Sheets ◽  
Four Point Bending ◽  
Externally Bonded ◽  
Strengthening Technique

Due to the advantages of Fiber Reinforced Polymer (FRP) materials, they have been utilized to strengthen several reinforced concrete (RC) elements such as slabs, beams and columns. In this paper, five RC beams (200 mm width, 300 mm height, and 2750 mm length) were constructed. Four of these beams were strengthened with CFRP sheets whereas the last beam was used as a reference. Test parameters include the amount of FRP and the strengthening technique. Three strengthening techniques were used including the externally bonded technique (EB), the near surface mounted (NSM) technique using folded CFRP sheets inserted in near surface grooves, and a hybrid technique. All beams were tested under four point bending setup until failure. The control beam failed by the yielding of the tension steel followed by concrete crushing. The strengthened beams failed by steel yielding followed by either rupture or debonding of CFRP sheets at higher loads compared to the reference one. The stiffness after steel yielding and the ultimate capacity increased as the amount of CFRP increased. The strengthening technique affected the ultimate capacity of the strengthened beams. The NSM beam showed the lowest increase in the ultimate capacity (25.2%) whereas the hybrid beam showed the best performance with the highest increase in the ultimate capacity (58%) compared to the reference beam.

Load Testing to Collapse Limit State of Barr Creek Bridge

2000 ◽  
Vol 1696 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Nicholas Haritos ◽  
Anil Hira ◽  
Priyan Mendis ◽  
Rob Heywood ◽  
Armando Giufre
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Flexural Rigidity ◽  
Load Capacity ◽  
Limit State ◽  
Dynamic Test ◽  
Service Condition ◽  
Flat Slab ◽  
Testing Program ◽  
Static Testing

VicRoads, the road authority for the state of Victoria, Australia, has been undertaking extensive research into the load capacity and performance of cast-in-place reinforced concrete flat slab bridges. One of the key objectives of this research is the development of analytical tools that can be used to better determine the performance of these bridges under loadings to the elastic limit and subsequently to failure. The 59-year-old Barr Creek Bridge, a flat slab bridge of four short continuous spans over column piers, was made available to VicRoads in aid of this research. The static testing program executed on this bridge was therefore aimed at providing a comprehensive set of measurements of its response to serviceability level loadings and beyond. This test program was preceded by the performance of a dynamic test (a simplified experimental modal analysis using vehicular excitation) to establish basic structural properties of the bridge (effective flexural rigidity, EI) and the influence of the abutment supports from identification of its dynamic modal characteristics. The dynamic test results enabled a reliably tuned finite element model of the bridge in its in-service condition to be produced for use in conjunction with the static testing program. The results of the static testing program compared well with finite element modeling predictions in both the elastic range (serviceability loadings) and the nonlinear range (load levels taken to incipient collapse). Observed collapse failure modes and corresponding collapse load levels were also found to be predicted well using yield line theory.

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