Linear Variable Differential Transducers Research Articles

Experimental verification of PEKK stiffened panel under compression

The paper presents the experimental strain and stress analysis of a thermoplastic composite stiffened panel subjected to compression load. The panel has five stringers with a non-symmetric design. Two panels are investigated. The experimental analysis deals with the pristine panel without any flaws and the panel with an artificial crack at the middle stringer interface with the skin. Panels were made from a thermoplastic polyetherketoneketone (PEKK) carbon composite. The buckling and mechanical analysis is based on digital image correlation, strain gauge measurements, and linear variable differential (LVDT) transducers. The crack subcritical extension was defined and analysed. The results show that crack propagation starts coupled with sudden buckling mode transition. The crack growth behaviour is influenced by the buckling shape, which consists of two main modes (with three and four half-waves) in the longitudinal direction in each skin bay.

The Harpers THMC flow bench: A triaxial multi-reactor setup for the investigation of long-term coupled thermo-hydro-mechanical-chemical fluid-rock interaction.

The scientific analysis and interpretation of coupled thermo-hydro-mechanical-chemical (THMC) processes in rocks requires complex and diverse instrumentation. In this study, we introduce the "Harpers THMC Flow Bench," a multi-cell, flow-through reactor system that allows long-term testing on rock plugs and powdered samples. The setup consists of four small triaxial cells that can hold confining and pore pressure of up to 20 MPa and an axial load of up to 300 MPa. Axial deformation of the samples is measured with linear variable differential transducers. The cells can be heated to 90 °C, and effluents (gas, water, and brine) can be sampled for compositional analysis. An additional Hastelloy-autoclave enables fluid mixing and saturation with gas prior to injection into the samples. Each cell can be operated individually, allowing independent experiments over long testing periods. The sample holders were designed such that they are transparent for X-rays during X-ray computer tomography, minimizing sample handling effects on the imaging results. To demonstrate examples of the capabilities of the flow bench, we present case studies on Carnmenellis granite (Cornwall, UK) and Castlegate sandstone (Utah, USA) samples. Permeability measurements are shown using fractured granite undergoing periodic loading of effective pressure. To demonstrate chemical measurement capabilities, we used deionized water to leach elements from granite powders. We then analyzed effluent compositions using inductively coupled plasma optical emission spectroscopy. Finally, we conducted a strength test and a cyclic differential stress test on sandstone to demonstrate the mechanical testing capabilities of the setup.

An experimental study on RC beams shear-strengthened with Intraply Hybrid U-Jackets Composites monitored by digital image correlation (DIC)

Reinforced concrete (RC) beams are commonly strengthened using steel stirrups, but these materials have limitations such as added weight and susceptibility to corrosion. Fiber-reinforced polymers (FRPs) offer a promising alternative to steel stirrups with high mechanical performance, low density, and resistance to corrosion and chemicals. In particular, Intraply Hybrid Composites (IRCs), which comprise multiple fibers oriented in different directions within a single matrix, have recently gained attention in the construction industry. Cakir et al. [1] investigated the use of three types of IRCs (Aramid-Carbon (AC), Glass-Aramid (GA), and Carbon-Glass (CG)) for strengthening 2-meter-long RC beams (the ratio of shear span (a) to effective depth (d) equals 3 (a/d = 3)) against shear fractures. In this study, the effects of these IRCs on the shear strength of 1.5-meter-long RC beams (a/d = 2) without transverse reinforcement were examined. In this scope, four-point bending tests were conducted on the beams after U-shaped IRC strengthening, and the impact of IRCs on shear strength was evaluated using both digital image correlation and classical measurement equipment such as strain gauges and linear variable differential transducers. The maximum load measured in RC1.5 was 194.50 kN, while the ultimate load capacity reached 265 kN in AC1.5, 246 kN in GA1.5, and 229 kN in CG1.5 after strengthening, representing increases of 36%, 26%, and 18%, respectively, compared to RC1.5. Additionally, the maximum mid-span deflections were determined as 30.40 mm, 16.10 mm, 22.20 mm, and 36.40 mm for RC1.5, AC1.5, GA1.5, and CG1.5, respectively. Moreover, the experimental results were compared with the predictions obtained from the international codes. It should be noted that the failure modes of RC beams are directly affected by the type of IRCs used, highlighting the significant contribution these materials can make to the structural behavior of RC beams.

Wireless coupling for LVDT sensor for reactor applications

Wireless coupling can offer significant advantages for in-reactor applications. For instance, wireless signal couplings can avoid electrical feedthroughs penetrating fuel cladding or other high-temperature pressure barriers in fuel performance testing. This paper presents a feasibility study of a wireless coupling technology for the linear variable differential transducer (LVDT), as LVDTs have been successfully demonstrated in reactor applications and can be used to measure a variety of physical parameters. The coupling technology utilizes mutual inductance at a low frequency to transfer power into and signal out of a stainless steel pressure barrier. Using Kirchhoff’s law and magnetic circuit analysis, a theoretical model is developed, including the LVDT, wireless power coupling parts, and wireless signal coupling parts. The LVDT is assumed to have a constant inductance of the primary coil and the sum of two secondary coils. An experimental system is built to test and verify the performance of the technology with a commercial LVDT. The experimental setup has an input voltage limitation to prevent the excessive heating. The non-linearity of the commercial LVDT is ±0.77% as measured in the lab. After coupling the LVDT with the wireless system, the measurement non-linearity is increased to ±1.26%, which shows the wireless power and signal transfer can be applied with LVDTs with limited additional measurement uncertainty. The theoretical model prediction agrees with the experiment results, with the maximum discrepancy of 1.5% between prediction and experiment. The model and experimental results of this study can be directly used to guide the design and optimization of wireless LVDT measurement systems for future in-reactor experiments.

Quantification of inhomogeneity and anisotropy of bituminous mixtures using biaxial experimental data

Most of the existing mechanical characterization test methods and the analytical models for bituminous mixtures are developed based on the assumption of homogenous and isotropic material properties. However, the extent to which such assumptions hold good for bituminous mixtures is not very clear. A biaxial testing scheme in indirect tension mode can come in handy to collect the experimental data at different test temperature regimes. In this study, a bituminous mixture with a nominal maximum aggregate size (NMAS) of 13.2 mm is used to fabricate cylindrical test specimens with 150 mm diameter and 63.5 mm thickness for conducting the repeated load indirect tension (IDT) test. The input load level is selected as 5 to 13 % of the indirect tensile (ITS) failure load in the form of a haversine pulse of 0.1 s loading and 0.9 s rest period. Such loading is applied on zero-degree and ninety-degree orientations of the specimen. The resulting deformations in different directions are measured using linear variable differential transducers (LVDT) attached to both diametral faces of the specimen. The response of the bituminous mixture specimen is captured at three different temperatures of 20, 25, and 30 °C using two different gauge length (half and quarter gauge of the total diameter). A new framework is introduced in this study to evaluate the extent of inhomogeneity and anisotropy of bituminous mixtures. The deformation response of the test specimen captured in the same orientation at different diametral faces is compared to evaluate the extent of inhomogeneity. The extent of anisotropy is evaluated by comparing the deformation response of the test specimen captured at different orientations within the same diametral face. A 15 % variation in the average peak deformation is chosen as the demarcation for determining the extent of inhomogeneity and anisotropy. From this investigation, it is observed that half gauge length experimental data exhibits homogenous and isotropic behavior for all three test temperatures. The quarter gauge length data exhibit similar behavior at 30 °C, whereas it is observed as homogenous and anisotropic at the other two test temperatures.

Development of a Laboratory Microcracking Procedure for Full-Depth Recycled Cement Stabilized Materials

Microcracking of full-depth recycled cement stabilized layers can be an effective method to mitigate the effect of reflective drying shrinkage cracks. To date, no effective method of performing microcracking in the laboratory has been developed. This is needed to determine appropriate levels of microcracking in the field, and to understand how the material will perform after microcracking. This paper covers the development and validation of a nondestructive laboratory procedure that can induce microcracking in specimens to controlled levels. The test setup used in this work was identical to that for the resilient modulus test, which facilitates stiffness measurement before and after microcracking. The use of on-specimen linear variable differential transducers is recommended to exclude end effects that can affect the stiffness result. The results indicate that: stiffness loss is a function of applied energy, and independent of the stress sequence; stiffness should only be calculated at low stress sequences, when the backbone of the stress–strain curve is linear, to accurately represent the stiffness of the material; microcracking effectively reduces the stiffness of the material; the microcracking test is a repeatable and nondestructive test; the stiffness reduction level is controllable; and the test can replicate microcracking effectively in the laboratory to represent microcracking in the field.

Full-scale testing and nonlinear finite element analysis of a pioneering fully prefabricated noise barrier wall system

The structural behavior of a novel fully prefabricated noise barrier wall system was examined experimentally and analytically using nonlinear finite element analysis. The wall components and connectivity details were developed to be a totally precast system for fast-track construction. Two full-scale prototypes were designed, fabricated, assembled, and prepared for full-scale testing at the High-Bay Structural Laboratory at the University of Illinois at Chicago. Each prototype was instrumented with about 40 sensors including strain gauges, linear variable differential transducers, and crack meters at pre-identified critical locations essential for understanding its structural behavior. In addition, a nonlinear finite element analysis model of the wall system prototype was required for future refinement and adjustment of the noise barrier wall system components. With proper calibration based on the experimental results, the nonlinear finite element analysis model will allow for conducting parametric studies on key factors relevant to the wall behavior without the need for costly and time-consuming full-scale testing. The structural behavior of the wall system was analyzed in terms of the load–deflection curves, load–strain curves, cracking, uplift, and failure mode. The experimental results revealed that the wall system was structurally stable up to a high loading level and met the intended serviceability and strength requirements.

Load-Bearing Performance of Non-Prismatic RC Beams Wrapped with Carbon FRP Composites

This study investigated the influence of CFRP composite wrapping techniques on the load–deflection and strain relationships of non-prismatic RC beams. A total of twelve non-prismatic beams with and without openings were tested in the present study. The length of the non-prismatic section was also varied to assess the effect on the behavior and load capacity of non-prismatic beams. The strengthening of beams was performed by using carbon fiber-reinforced polymer (CFRP) composites in the form of individual strips or full wraps. The linear variable differential transducers and strain gauges were installed at the steel bars to observe the load–deflection and strain responses of non-prismatic RC beams, respectively. The cracking behavior of unstrengthened beams was accompanied by excessive flexural and shear cracks. The influence of CFRP strips and full wraps was primarily observed in solid section beams without shear cracks, resulting in enhanced performance. In contrast, hollow section strengthened beams exhibited minor shear cracks alongside the primary flexural cracks within the constant moment region. The absence of shear cracks was reflected in the load–deflection curves of strengthened beams, which demonstrated a ductile behavior. The strengthened beams demonstrated 40% to 70% higher peak loads than control beams, whereas the ultimate deflection was increased up to 524.87% compared to that of the control beams. The improvement in the peak load was more prominent as the length of the non-prismatic section increased. A better improvement in ductility was achieved for the case of CFRP strips in the case of short non-prismatic lengths, whereas the efficiency of CFRP strips was reduced as the length of the non-prismatic section increased. Moreover, the load–strain capacity of CFRP-strengthened non-prismatic RC beams was higher than the control beams.

Monitoring Pergeseran Tanah Tapak Tower Transmisi PT (PLN) Persero Dengan Menggunakan SMS Sebagai Notifikasi Peringatan

Landslides are one of the causes of the collapse of the transmission tower of PT PLN (Persero) which caused power outages, therefore monitoring the shifting of the transmission tower tread is very necessary so that power outages due to the collapsed tower can be anticipated faster. In this study the authors made a study to monitor tower shifts by using Ultrasonic sensors and LVDT sensors (Linear Variable Differential Transducer), Ultrasonic sensors function to detect shifts from towers and LVDT sensors function to detect shifts from the left and right tread tower ground. In this research, there are three main sensors, namely 2 LVDT sensors and one Ultasonic sensor - each sensor is placed in a safe position from interference and has the least possibility of being affected by landslides, Ultrasonic sensors read the tower shift towards the sensor mounted on the center side and LVDT sensors read the shift ground tread tower on the left and right side of the tower. The sensor sends the signal then is converted by the ATMega 8535 microcontroller into a millimeter unit for LVDT sensors and centimeter meter for Ultrasonic sensors. To find out the changes that occur in the tower and tower ground. Every change in distance or the occurrence of a microcontroller shift sends event data in the form of tower numbers and tower shift distances from each sensor reading using SMS (Short Message Service) communication. The installed LVDT sensor has a reading accuracy rate of 98,05% for LVDT 1 and 98,98% for LVDT 2 in millimeters and an Ultrasonic sensor has a reading accuracy rate of 99,44% in centimeters.

Vision-based real-time structural vibration measurement through deep-learning-based detection and tracking methods

Structural vibration measurement is crucial in structural health monitoring and structural laboratory tests. Traditional contact type sensors are usually required to be attached to the test specimens, which may be difficult to install, and may affect the structural properties and response. Non-contact type wireless sensors are usually expensive and require specialized workers to install and operate. In recent years, vision-based tracking methods for structural vibration measurement have gained increasing interests due to their high accuracy, non-contact feature and low cost. However, traditional vision-based tracking algorithms are susceptible to external environmental conditions such as illumination and background noise. In this paper, two real-time methods, YOLOv3-tiny and YOLOv3-tiny-KLT, are proposed to track structural motions. In the first method, YOLOv3-tiny is established based on the YOLOv3 architecture to localize customized markers where structural displacements are directly determined from the bounding boxes generated. The second method, YOLOv3-tiny-KLT, is a more advanced method which combines the YOLOv3-tiny detector and the traditional KLT tracking algorithm. The pretrained YOLOv3-tiny is deployed to localize the targets automatically, which will then be tracked by Kanade‐Lucas‐Tomasi algorithm. YOLOv3-tiny is intended to provide baseline vibration measurement when the KLT tracking gets lost. The proposed methods were implemented for the videos of shake table tests on a two-storey steel structure. Parametric studies were conducted for the YOLOv3-tiny-KLT method to examine its sensitivity to the tracking parameters. The results show that the proposed method is capable of achieving real-time speed and high accuracy, when compared with the traditional displacement sensors including linear variable differential transducer (LVDT) and String Pots. It is also found that the combined YOLOv3-tiny-KLT approach achieves higher accuracy than YOLOv3-tiny only method, and higher robustness than KLT only method against illumination changes and background noise.

Target-free vision-based approach for modal identification of a simply-supported bridge

Accurate and efficient vibration response measurement is one of the key tasks in structural health monitoring (SHM) of civil engineering structures. Normally, dynamic responses such as displacement responses, are acquired by physical sensors and data acquisition systems installed on the structures. However, the installation of sensors may be time-consuming and costly. In recent decades, computer vision-based methods have been introduced into civil engineering to provide alternatives for traditional displacement measurements. However, the camera specifications, such as limitations on field of view (FOV) and relatively low resolution of economic lens, have prevented the vision-based method from being widely used for vibration displacement measurement on relatively large-scale structures. This paper proposes a target-free vision-based approach for dynamic displacement measurement and modal identification of simply-supported bridges using a single camera. In this study, a series of videos are captured in separate experimental tests using a consumer-class GoPro on a long-span beam subjected to a moving load. The radial distortion of videos caused by the wide-angle lens is offset by distortion adaption, and the scale factor is fitted using a static video shooting experiment. The tracking process consists of three basic steps, namely, region of interest (ROI) selection, natural feature extraction and features tracking. The results are compared with those measured by linear variable differential transducer (LVDT), demonstrating a high accuracy by the proposed approach. Vibration characteristics, including natural frequencies and mode shapes of the bridge, are identified from the measured displacement. The overall mode shapes are obtained by combining the mode shapes identified from different segmental videos of the bridge obtained by roving the single camera along the bridge for measurements. Comparisons of the natural frequencies and mode shapes between the results from the proposed approach and LVDTs demonstrate the effectiveness and accuracy of the proposed approach for displacement measurement and modal identification of long bridges under moving loads.

Optimization of the magnetic core of a Linear Variable Differential Transducer

Optimization of the magnetic core of a Linear Variable Differential Transducer

Modelling and design of low-power, non-conventional current sensors based on smart materials for high-voltage transmission lines

This paper presents a new technique for measurement of current based on magnetic shape memory (MSM) smart alloys. MSM alloys undergo shape changes when exposed to magnetic fields. The non-conventional instrument transformer (NCIT) proposed in this paper utilises this property to measure current. There is a correlation between the magnetic field produced by a current and the shape change of an MSM material (MSM sensor). By exploiting this correlation, we have shown that it is possible to measure alternating currents (a.c.) in high voltage overhead transmission lines. A change in the length of the MSM element causes voltage output in a linear variable differential transducer. The design of the NCIT was optimised for transmission lines. Several designs of its magnetic circuit were simulated using finite element package ANSYS APDL. Several key parameters were investigated to evaluate their effects on the sensitivity of the NCIT. Results are presented as the relationship between the current in the conductor and strain (linear elongation) of the MSM element. A commonly used conductor in high-voltage transmission lines was modelled together with the MSM element and the magnetic circuit. Recommendations have been made on the design of NCITs considering various parameters. In addition, analyses of errors in ANSYS models for the magnetic circuit have been presented. The developed methodology and obtained results are verified by comparing them to the results obtained through an experiment done by a manufacturer of MSM materials.

Investigation of CFRP Reinforcement Ratio on the Flexural Capacity and Failure Mode of Plain Concrete Prisms.

The utilization of carbon-fiber-reinforced polymer (CFRP) composites as strengthening materials for structural components has become quite famous over the last couple of decades. The present experimental study was carried out to examine the effect of varied widths of externally bonded CFRP on the debonding strain of CFRP and the failure mode of plain concrete beams. Twelve plain concrete prims measuring 100 mm × 100 mm × 500 mm were cast and tested under identical loading conditions. The twelve specimens include two control prisms, i.e., without CFRP strips, and the remaining ten prisms were reinforced with CFRP strips with widths of 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm, respectively, i.e., two prisms in each group. Four-point loading flexural testing was carried out, and the resulting data are presented in the form of peak load vs. midpoint displacement, load vs. concrete strain, and load vs. CFRP strain. The peak load was directly recorded from the testing machine, while the midpoint deflection was recorded through the linear variable differential transducer (LVDT) installed at the midpoint. To measure the strain, two separate strain gauges were installed at the bottom of each concrete prism, i.e., one on the concrete surface and the other on the surface of the CFRP strip. The results of this study indicate that the debonding strain is a function of CFRP strip width and that the failure patterns of beams are significantly affected by the CFRP reinforcement ratio.

Accuracy of an Apparatus for Measuring Glenoid Baseplate Micromotion in Reverse Shoulder Arthroplasty

Abstract Reverse shoulder arthroplasty (RSA) is used to treat patients with cuff tear arthropathy. Loosening remains to be one of the principal modes of implant failure and the main complication leading to revision. Excess micromotion contributes to glenoid loosening. This study sought to determine the predictive accuracy of an experimental system designed to assess factors contributing to RSA glenoid baseplate micromotion. A half-fractional factorial experiment was designed to assess 4 factors: central element type (screw versus peg), central element length (13.5 versus 23.5 mm), anterior-posterior peripheral screw type (locking versus nonlocking) and cancellous bone density (10 versus 25 pounds per cubic foot (pcf)). Four linear variable differential transducers (LVDTs) recorded micromotion from a stainless-steel disk surrounding a modified glenosphere. The displacements were used to interpolate micromotion at each peripheral screw position. The mean absolute percentage error (MAPE) was used to determine the predictive accuracy and error range of the system. The MAPE for each condition ranged from 6.8% to 12.9% for an overall MAPE of (9.5 ± 0.9)%. The system had an error range of 2.7 μm to 20.1 μm, which was lower than those reported by prior studies using optical systems. One of the eight conditions had micromotion that exceeded 150 μm. These findings support the use of displacement transducers, specifically LVDTs, as an accurate system for determining RSA baseplate micromotion in rigid polyurethane foam bone surrogates.

Effectiveness of Selected Strain and Displacement Measurement Techniques in Civil Engineering

The aim of this study was to assess how useful certain selected measurement techniques are in civil engineering. In this work, the focus was placed on the measurement of displacement and strain. Classical methods with an established position in the industry, such as electrical resistance strain gauge measurements and linear variable differential transducers (LVDT), were compared with modern techniques that do not require direct contact with the measured object, such as laser scanning and digital image correlation. A simply supported beam was bent in two types of tests. In the first test, a small load was applied on the beam, causing a slight deflection of the structure of approximately 0.5 mm. This enabled us to assess how effective the tested methods were, given the very precise measurement of the structure. In the second test, a much higher load was introduced, which caused displacement that can realistically be found in actual civil engineering structures. Ultimately, the model went through the plastic phase and was damaged. This enabled the measurement of displacement and strain that were much higher than those of the safe operating range of the structure. Based on conducted examinations, practical conclusions were drawn relative to the analyzed measurement methods.

Experimental and Finite Element (FE) Studies on the Behaviour of Horizontally Curved Composite Bridges Deck

This paper aims to study the behaviour of horizontally curved composite steel-concrete bridges deck slab and beams under static load, using experimental tests and nonlinear finite element analysis. Two different specimens were examined in the structure laboratory, one of them was horizontally curved composite deck slab and steel girders with full interaction between the concrete deck and the steel girders, while the other with partial interaction. Each specimen has three curved I-girders acted parallel connected with X shape cross frames. Linear Variable Differential Transducers (LVDT) and strain gauges were used at critical points to measure deflections and strain respectively. Three dimensional finite element (FE) models with 137119 elements were built and analysed using ANSYS software version 14. Models dimensions were 1/10 in both length and radius of curvature of the Federal Highway Administration (FHWA) full scale model. Numerical results have been compared with the experimental test results. Maximum values and distribution of both stresses and strains at top flanges, bottom flanges and the web tension zone for numerical modelling results, showed close agreement with the experimental tests results in both full and partial interaction models. Also, similar failure modes were encountered from both numerical modelling and experimental tests. Maximum deflection values obtained from numerical modelling were slightly below the experimental values and this was attributed to the stiffer numerical model. Further, mesh refinement could have increase accuracy of numerical predictions.

Distributed fibre optic sensors in FRP composite bridge monitoring: Validation through proof load tests

The distributed fibre optic sensors (DFOS) technique based on Rayleigh scattering has been chosen as the basic structural health monitoring (SHM) system of the first Polish fibre reinforced polymer (FRP) composite bridge. The validation of the DFOS technique is critical to address the development of a monitoring system with improved accuracy and spatial resolution tailored for the FRP bridge application. The validation through proof load tests and finite element analysis (FEA) has been performed to ensure accurate and reliable DFOS readings. Two additional strain measurements techniques were implemented to validate DFOS, i.e. common foil strain gauges and vibrating wire strain gauges. The DFOS strain profiles were first compared with discrete strain measurements and then converted into deflection profiles and validated against discrete deflection measurements performed with common linear variable differential transducers. The additional validation based on the comparison of the measurement profiles with the results of FEA has been also performed. Based on the experimental and numerical results it has been revealed the DFOS technique is a reliable and accurate method to be implemented for FRP bridge monitoring.

Deformation behavior of D-Shaped shallow tunnels under dynamic loading conditions

Underground tunnels have offered a quick and cost - effective alternative for storage, traffic, and transportation in many countries. Due to intensive and more frequent occurrences of worldwide terrorism attacks on urban tunnels, there is a need to develop a methodology for designing underground structures that can withstand such attacks [14]. Therefore, in the present study, the physical modeling of D-Shaped shallow tunnels is carried out to understand tunnel behavior when subjected to a high rate of impact loading (projectile). To understand the tunnel deformation behavior, an extensive experimental investigation is performed on the physical model of the tunnel in synthetic rockmass subjected to impact loads. For rock-tunnel modeling, three different cover depths are considered. The impact loads of varying magnitude are applied at the center using drop hammer equipment. The deformation of the tunnel crown is measured along the tunnel length by means of a linear variable differential transducer (LVDT).Further, the finite element method based numerical investigation is carried out by using Abaqus/CAE numerical tool. The validation of the numerical model is performed by using the experimental results. It is found that the cover depth plays a vital role in determining the overall stresses and deformation when the tunnel is subjected to either static or dynamic loading. From the experimental and numerical investigations, it has been observed that the tunnel with the lowest cover depth experience excessive deformation, and the zone of influence, i.e., area through which crack propagates, is less. The maximum deformation along the tunnel length is observed in the D-Shaped shallow tunnel as compared to the Circular Shape tunnel.

Effect of steel fibres on concrete at different temperatures in terms of shear failure

The behaviour of concrete reinforced with steel fibres at elevated temperatures was investigated in terms of shear deterioration. Using three different steel fibre contents (0, 40 and 80 kg/m3), 45 push-off specimens were tested at five maximum temperatures (20, 150, 300, 500 and 700°C). The main objective of the research was to investigate the effect of steel fibres on the behaviour of concrete at different maximum temperatures in terms of shear failure. The results revealed enhanced ductility and shear strength at elevated temperatures. In addition, the crack widths and crack slips were measured using linear variable differential transducers. It was found that the use of steel fibres increased the shear strength of the concrete at ambient temperature by 103% and 102% for steel fibre contents of 40 and 80 kg/m3, respectively. Although this enhancement was reduced at the high temperatures (500 and 700°C), the mixes containing fibres still had higher residual shear strengths than the plain concrete mix. The steel fibre content also affected the ductility at both ambient and high temperatures.