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Structural engineers have assessed the possibility of replacing part of natural aggregates with rubber particles in concrete in recent years to obtain sustainable structural members. It has been confirmed that the use of rubber particles can enhance ductility and energy absorption capacity of concrete. By contrast, the compressive capacity of rubberized concrete (RuC) is usually lower than the normal concrete (NC). Confining RuC with steel tubes can be considered as an appropriate solution for reaching to a ductile member with adequate strength. This paper, therefore, investigates the behavior of rubberized concrete-filled double skin steel tubular (RuCFDST) short columns by performing a series of nonlinear finite element (FE) analyses. The developed FE models were verified against the experimental test results by comparing the axial load–displacement curves, ultimate axial strength, and failure mechanism of specimens. The validated FE model was used to investigate the effects of geometric and material properties on the behavior of RuCFDST columns with 5%, 15%, and 30% rubber contents, and to compare the performance of RuCFDST and concrete-filled double skin steel tubular (CFDST) columns. The results showed that using RuC for filling square CFDST columns could significantly enhance the ductility. By contrast, CFDSTs presented greater axial strengths than RuCFDSTs. Reduced confining stresses between the outer tube and the concrete core were displayed when RuC was applied compared to CFDST.

Structural strengthening comprises modification of the structural elements to enhance their load bearing capability, stiffness, toughness, and ductility. The present study is an experimental investigation on the performance of reinforced concrete (RC) beam specimens strengthened by the side near surface mounted (SNSM) technique with reinforcement strengthening of glass fiber reinforced polymer (GFRP) bars in flexure. Sustainable palm oil fuel ash (POFA) mortar (PM) and normal mortar were used as bonding mediators between the concrete substrate and GFRP bars as a replacement for epoxy adhesive. A total of eight specimens, in which one was a control, one was strengthened by GFRP bars and full epoxy adhesive in grooves, and six specimens were strengthened by GFRP bars and partial replacement of epoxy adhesive by PM and NM, respectively. The specimens were tested in the static condition under four-point bending. During the test, the loads, deflection, and strains of the specimens were stored in a data logger and the failure modes of the specimens were observed. Critical discussions were made based on the flexural capacities, load-deflection, ductility, energy absorption, the influence of epoxy replacement and the type of mortars in the strengthened specimens as compared to the control specimen. ACI 440.2R-08 and ACI 318-11 were applied to predict the ultimate load-carrying capacity and deflection characteristic graphs of the tested specimens. The predicted results of the specimens were in close agreement with the experimental results. The test results also exhibited that the epoxy substituted by sustainable PM had superior flexural performance to the NM strengthened SNSM-GFRP bar specimens, particularly when considering the economic and eco-friendly viewpoint.

In this study, grouted couplers were used to connect steel bars as an alternative approach to the conventional steel bar lapping method. The aim is to avoid bar congestion problems and to reduce the required quantity of steel bars in order to achieve the development length in practice. Two categories of couplers, i.e., short-threaded grout coupler and long grout coupler, in nine groups as well as one group of deformed bars, were tested under uniaxial tension. In total, 30 samples (including three repeated samples in each group) were tested. The examined parameters were types of couplers, embedded bar length, and bar eccentricity. For the short-threaded grout couplers, the embedded bar length, which is equivalent to 8 times bar diameter with bar eccentricity equal to zero, exhibited the best performance in terms of strength, ductility, energy absorption, and failure mode, which is suitable to be used in the high seismic zone. Additionally, the short-threaded grout couplers with the embedded bar length equal to 7 times bar diameter and the long grout couplers that required embedded bar length that is equal to 8 times bar diameter, are suitable to be used in the low-to-medium seismic zone. Besides, the embedded bar length that is smaller than or equal to the 6 times bar diameter was not sufficient to be utilised in the short-threaded grout couplers and long grout couplers to resist the seismic load due to inadequate bar embedded length. Also, the predicted model is sufficient to estimate the ultimate tensile strength of the grouted couplers.

Oil-palm-boiler clinker (OPBC) is an agricultural waste from the palm oil industry and is considered a serious threat to the environment. Moreover, the high consumption of concrete as a construction material results in a continuous demand for natural aggregates, thereby negatively affecting the environment. Thus, channeling OPBC waste materials into the concrete industry aids in promoting the use of a sustainable and lightweight member. This research presents a novel sustainable composite beam that uses an OPBC as a replacement of the natural coarse aggregate. Flexural behaviour of steel tubes infilled with conventional and OPBC concretes were investigated. The results showed that the ductility, flexural stiffness and structural efficiency were higher in the OPBC concrete filled steel tube (CFST) than conventional CFST by 15%, 12% and 20%, respectively. Furthermore, in comparison to conventional CFST, the 10% less self-weight in OPBC CFST will significantly reduce the construction cost of the material. Conclusively, the utilisation of OPBC as infill material for CFSTs will solve disposal problem, preserve natural resources, reduce environmental pollution and will make the structural system sustainable.

Side Near Surface Mounted (SNSM) strengthening technique is among the latest technique introduced recently. In this paper, SNSM carbon fiber reinforced polymer (CFRP) strips strengthening technique is proposed for enhancing the flexural performance of reinforced concrete (RC) beams. A total of seven RC beam specimens were tested: one un-strengthened control specimen, and six specimens strengthened by SNSM-CFRP strips. All beam specimens were tested under four-point bending. Analytical prediction methods were used to verify the experimental results. The load, mid-span, deflection, and strains data were recorded until failure of the specimens. The ductility, stiffness, and energy absorption capacity of the strengthened specimens by CFRP strips were enhanced due to SNSM technique. The results also showed that the SNSM-CFRP strips strengthening technique significantly enhanced the first cracking, yield, and ultimate load capacities up to 153%, 108%, and 147% respectively, compared with that of the control beam. Further, the comparison between the experimental and predicted values shows good agreement.

The utilisation of beam to concrete-filled tubular (CFT) column bolted construction remains limited due to the severe slippage of bolts, column surface deformation and low moment-resisting capacity. This study proposes a novel blind bolt, known as the TubeBolt, for beam to CFT column connections. Ten pull-out test specimens were evaluated under tensile monotonic loading. Bolt type, bolt diameter, end anchor member, hollow tube wall thickness and bolt hole diameter were varied for the test. The failure modes, anchorage performance, load-carrying capacity, strength, slippage and elongation of the bolts were analysed. The behaviour of the TubeBolt specimens was compared with that of the Extended Hollo-bolt specimens under the same condition. Experimental results indicated that the novel TubeBolt in concrete-filled tubes exhibited excellent anchorage performance, higher strength and less slip and elongation until the failure state was reached.

In general, precast concrete structure has insufficient ductility to resist seismic load. Detailed understanding on the behaviour of precast concrete connections are limited and current researches are focused addressing this. In this study, two precast and two monolithic concrete joints for exterior beam-to-column connection were tested under cyclic loading. The installation of precast specimens was prepared using dry type method while the monolithic joints were casted in-situ. The evaluation of seismic performance of the joints was conducted by applying hysteretic reverse cyclic loading until failure. Information regarding the strength, ductility and stiffness properties of the connection were recorded and analysed. Based on the test results and damage condition, the initial design of the joint was improved. Consequently, a new joint was constructed and tested, which exhibited a better performance. Precast concrete connections showed stable load–displacement cycles and dissipated a higher energy. The structural drift obtained was up to 9.0%. Pinching and deterioration were attained at a drift ratio of 4.5%. Also, there was improvement in the tested precast joints based on deflection, plastic hinges, crack pattern and shear deformation. Thus, the precast joints had a satisfactory resistance to seismic loads.

In this research, numerical investigations were carried out to study the behaviour of concrete filled steel tubes having square or rectangular cross-sections. Separate models were used for both normal strength concrete and high strength concrete. More than 50 experimental results were used to verify the FE model and it was found that the FE model accurately predicts the load-deflection curve and ultimate moment capacity of the Concrete filled steel tube (CFST) beams. Thereafter, a parametric study was carried out to evaluate the effect of depth-to-thickness ratio (20−200), compressive strength of infilled concrete (2–100 MPa), shear span-to-depth ratio (1–8), depth-to-width ratio (0.6–2), and yield strength of steel tube (380–490 MPa) on the flexural behaviour of square and rectangular CFST members. It was found that the depth-to-thickness ratio, yield strength of steel and height-to-width ratio has significant effect on the ultimate capacity of CFST beams. The effect of shear span-to-depth ratio and strength of infilled concrete was found to be marginal. Finally, the results of parametric study and experimental data available in literature were used to check the accuracy of the existing design methods presented in EC4 (2004), CIDECT, AISC (2010) and GB50936 (2014). From comparison, it was found that GB50936 (2014) was more accurate but unsafe for low strength infilled concrete. For all cases, EC 4 (2004) was found to be safe and hence is recommended.

Huge amount of virgin materials is being used in the production of concrete and the negative impact caused by exploitation of natural resources to our eco-system is beyond recovery. In order to produce a cleaner and greener concrete, waste palm oil clinker (POC) powder, a by-product from palm oil industry was used as filler and amorphous material in the development of sustainable and environmental friendly lightweight concrete. The utilization of POC powder as cement replacement in concrete will certainly have positive impact on the environment due to potential reduction in greenhouse gas emission. Further, whole replacement of virgin crushed granite coarse aggregate with coarser POC as coarse aggregate would enable conservation of natural resources. The properties including workability, density, compressive strength in different moisture contents, splitting tensile and flexural strengths, stress-strain curve, modulus of elasticity, ultrasonic pulse velocity (UPV) water absorption and sorptivity of the sustainable lightweight concrete were obtained and analysed. It has been found that the addition of 15% waste POC powder produced the optimum mixture as the strength enhancement of compressive and flexural strengths of 30% and 15%, respectively, was found. In addition, the filler effect of waste POC powder could be seen as it decreased the water absorption and sorptivity. Moreover, the use of two palm oil industrial waste materials up to a volume of 56% in concrete as replacement to cement and coarse aggregate will not only reduce cost but it will spur research and commercial interests as environmental friendly high strength lightweight concrete could be produced using these wastes.

Concrete-filled steel tubular (CFST) columns have been used in the construction of modern structures such as high-rise buildings and bridges as well as infrastructures as they provide better structural performance than conventional reinforced concrete or steel members. Different shapes of CFST columns may be needed to satisfy the architectural and aesthetic criteria. In the study, three dimensional FE simulations of circular, square, hexagonal, and octagonal CFST stub columns under axial compression were developed and verified through the experimental test data from the perspectives of full load-displacement histories, ultimate axial strengths, and failure modes. The verified FE models were used to investigate and compare the structural performance of CFST columns with different cross-section shapes by evaluating the overall load-deformation curves, interaction stress-deformation responses, and composite actions of the column. The extent of the ultimate-axial-strength enhancement due to enhanced steel yield strength and concrete compressive strength was evaluated through the parametric studies. At last, the accuracy of available design models in predicting the ultimate axial strengths of CFST columns were investigated. Research results showed that the behaviors of hexagonal and octagonal CFST columns were generally similar to that of the square CFST column as their overall structural performance was relatively improved.

Structural performance of steel-concrete composite structures relies deeply on the characteristics of the shear connectors. Recently, great attention has been focused on the implementation of C-shaped connectors due to numerous advantages when used in composite beams. However, very little information is available in regard to the response of such connectors when embedded in the high strength concrete (HSC). To address this research gap, sixteen experiments on push-out specimens were conducted to compare the performance of channel and angle shear connectors embedded in HSC. The shear resistance and ductility of the connectors were primarily investigated by applying static and cyclic loadings. Results were also compared with the cases when using normal reinforced concrete. Furthermore, the evaluation of the available equations suggested by the American and Canadian codes for estimating these connectors' capacities when using HSC was carried out. In general, channel connectors exhibited 6.8-30.1% more shear strength than those of angle under monotonic loading, and up to 18.5% more when subjected to cyclic loading. Angle connectors were also less ductile than channel connectors and did not satisfy the ductility criteria specified in the codes' requirements. Connector fracture mode of failure was recorded for both connector types.

Beam-to-column connections (BCCs) in steel pallet racks (SPRs) govern the stability of the structure in the down-aisle direction and possess a complex behavior as compared with the customary steel connections used in building structures because of the absence of bolts and welds. This behavior becomes increasingly complicated in case of hazardous conditions, such as fire, and needs careful design considerations. Warehouse fires are associated with higher average property losses per fire than most other occupancies. The existing literature completely lacks the studies focusing on the behavior of SPR BCCs under fire. This paper predicts the experimental and numerical behavior of SPR BCCs subjected to elevated temperatures. Eight sets of connection specimens, with three specimens in each set, were selected based on the variation in column thickness, beam depth, and the number of tabs in the beam end connector. A total of twenty-four tests were performed at three different temperature ranges (450 °C, 550 °C, and 700 °C) using the double cantilever test method. The major failure modes and the moment-rotation (M-θ) behavior of the SPR BCCs at elevated temperatures were evaluated and compared with the results of ambient temperature testing of SPR BCCs available in the literature. The findings indicated a noticeable degradation in the strength and stiffness of the connection due to thermal action. A non-linear three-dimensional (3D) Finite element (FE) model was developed to simulate the experimental investigations. The FE model exhibited a close agreement with the experimental results.

Tubular column members have been widely adopted in current construction due to its numerous advantages. However, the closed-section profile characteristics of tubular columns severely limit the connection possibilities. Welding type is acceptable but discouraged because of on-site issues. Blind-bolted connection is preferable because of its simplicity, economic benefit, and easy assembly. This paper presents a state-of-the-art review on bolted connections to tubular columns for bare steel tubes, including square and circular sections. Available studies on bolted connections at ambient and elevated temperatures are reviewed, but emphasis is given on the latter. Various methods of determining the connection performance through experimental, analytical, component based, and finite element approaches are examined. Future research areas are also identified.

Nonlinear finite element models of through beam connection to concrete filled circular steel tube (CFCST) column with three types of connection failures (column, beam and joint shear failures) under monotonic loading were proposed by ABAQUS programme. The connection detail composed of a steel I-beam which is completely passed through the circular steel tube column and welded to it by fillet or full penetration weld and the tube is then filled with concrete. The connection parameters investigated included different ratios of column-to-beam flexural strength, fillet or full penetration weld to connect the beam to the tube, using rebar inside of the column and effect of beam web and concrete core inside the joint. Buckling analysis, concrete damage, weld fractured and tube tearing were defined in the model. Good agreement was achieved between the model and existing test results in terms of the beam tip force-storey drift relationship, joint distortion and joint shear strain. As a result, the models could correctly predict the linear, nonlinear and post-failure behaviours of the connection. In addition, other parameters of the connection were investigated for the specimens. Finally, the effect of column axial load level for the connection behaviour in the three types of failures was investigated as a parametric study.

Concrete-filled steel tubes (CFTs) exhibit superior performance under static and dynamic loads, due to composite action. Factors, such as the thickness of the steel tube and the concrete core condition, have a significant effect on the structural behaviour of CFT columns, particularly in the post-yield behaviour. Studies show that if the concrete core is reinforced with steel bars, the new composite member has better characteristics compared to CFT columns. In this study, the axial compressive behaviour of reinforced concrete-filled steel tube (RCFT) columns using spirally reinforced concrete (SRCFT) was investigated and compared with CFTs. The main variation was the pitch spacing of the spiral shear reinforcement. Fifteen specimens, including three CFTs and twelve SRCFTs, were tested in five groups. The test results indicated that a SRCFT column has much better post-yield behaviour than a CFT column. A reduction in the pitch spacing rate further improves the post-yield behaviour of the SRCFTs. A comparison of the measured strength of the specimens with corresponding values predicted by two international codes (ACI 318-11 and EC4-1994) shows a good prediction of EC4 and a conservative estimation of ACI.

The behavior of shear connectors plays a significant role in maintaining the required strength of a composite beam in normal and hazardous conditions. Various types of shear connectors are available and being utilized in the construction industry according to their use. Channel connectors are a suitable replacement for conventional shear connectors. These connectors have been tested under different types of loading at ambient temperature; however, the behavior of these connectors at elevated temperatures has not been studied. This investigation proposes a numerical analysis approach to estimate the behavior of channel connectors under fire and compare it with the numerical analysis performed in headed stud and Perfobond shear connectors subjected to fire. This paper first reviews the mechanism of various types of shear connectors and then proposes a non-linear thermomechanical finite element (FE) model of channel shear connectors embedded in high-strength concrete (HSC) subjected to fire. Initially, an accurate nonlinear FE model of the specimens tested at ambient temperature was developed to investigate the strength of the channel-Type connectors embedded in an HSC slab. The outcomes were verified with the experimental study performed on the testing of channel connectors at ambient temperature by Shariati et al. (2012). The FE model at ambient temperature was extended to identify the behavior of channel connectors subjected to fire. A comparative study is performed to evaluate the performance of channel connectors against headed stud and Perfobond shear connectors. The channel connectors were found to be a more economical and easy-To-Apply alternative to conventional shear connectors.

Shear connectors are key components to ensure the efficient composite action and satisfactory transfer of shear forces at the steel'concrete interface in composite beams. Under hazardous circumstances, such as fire in a building, the performance of a composite beam significantly relies on the performance of shear connectors. Studies on the behavior of shear connectors subjected to elevated temperatures performed in the last decade are reviewed in this paper. The experimental testing of push-out specimens, the design approaches provided by researchers and different codes, the major failure modes, and the finite element modeling of shear connectors are highlighted. The critical research review showed that the strength of a shear connector decreases proportionally with the increase in temperature. Compared with the volume of work published on shear connectors at ambient temperatures, a few studies on the behavior of shear connectors under fire have been conducted. Several areas where additional research is needed are also identified in this paper.

In this paper a new shear connector called V-shaped angle shear connector for steel–concrete composite system is proposed. This shear connector was proven to improve some mechanical properties of shear connectors, including high shear transfer, uplift resistance, sufficient ductility, and strength degradation resistance under cyclic loading, as well as to being cost effective compared with similar shear connectors, such as C-shaped channel and angle shear connectors. A total of 14 push-out tests were performed on composite beams with these connectors under monotonic and low cyclic loading. The failure mode, shear resistance, and ductility of the push-out specimens were investigated. The study also comprises of finite element and parametric analysis using an effective numerical model of the experimental push-out tests using the program ABAQUS. The finite element models were validated against the test results presented in experimental tests. Results showed that V-shaped angle shear connector has excellent behavior in terms of both shear strength and ductility. In addition, high resistance under cyclic loading was exhibited since the shear resistance of this connector was almost similar in both monotonic and cyclic loadings. Finite element results show good agreement with experimental results. The results discussed on the ductility and strength of this connector with different size and slope of inclination. In addition, the channel and angle shear connectors were compared with V-shaped angle shear connectors. V-shaped angle shear connectors behave much better than other similar connectors, such as normal angle shear connectors, and are superior to channel shear connectors in most specimens.

In this paper, the effectiveness of cement mortar as bonding materials in the strengthening of reinforcements and concrete surface for flexural improvement of reinforced concrete (RC) beams were investigated. Recently, side near surface mounted (SNSM) and existing near surface mounted (NSM) techniques with glass fiber reinforced polymer (GFRP) bars are adopted as the strengthening methods for RC beams in which varieties of epoxy adhesive were replaced with cement mortar. In this study, one control and seven strengthened beams were tested under four-point loading in a static condition. The load-carrying capacities, failure modes, deflection, strains characteristic, parametric study and energy absorption capacities are addressed through laboratory experiments. The results revealed that the flexural performance was successfully achieved by using cement mortar as a replacement for adhesive. The SNSM strengthening technique exhibited better structural performance compared with the existing NSM technique in all aspects.

Structural connection systems are a major challenge for precast construction systems. A dowel system requires designers to have sound knowledge of the fundamental requirements for seismic loads. In addition, it is important to consider unforeseen impact loads to prevent buildings from collapsing in the event of an earthquake. At present, the available building codes does not offer a complete design and analysis requirements for beam-to-column connection systems. Thus, this article provides researchers with a comprehensive review of the literature of the dowel precast beam-column connections. The key areas covered in this review are as follows: (1) studies on the behaviour of precast dowel beam-column connection systems in earthquake-prone areas; (2) studies on the design and development of precast dowel connection elements; (3) an evaluation of the effect parameters in precast connection systems and (4) a determination of the appropriate precast beam-to-column connections for seismic loads. The strength, ductility, energy dissipation, rotation and plastic hinges of joints in critical regions were considered in order to evaluate the performance of the dowel connection system.

The existing literature concerning the axial performance of concrete-filled double-skin steel tubular (CFDST) columns has been reviewed in this paper. The models in the literature for predicting the behavior of steel materials and confined concrete are summarized, and their effects of the results of finite element analysis are discussed. The applicability and accuracy of four design guidelines to predict the ultimate axial strength of CFDST columns have been assessed through this review by using an expanded database of published compression tests. Code limits in cross-sectional slenderness and material strength are reviewed. The impacts of different structural parameters on the axial behavior are reviewed and discussed. The discussion results indicate that material properties and dimensions have significant effects on the axial performance of CFDST columns. The European and Australian codes give the most reliable predictions, while American design codes give conservative predictions. Finally, recommendations for future studies are provided.

This research strives to develop a high-temperature resistant lightweight aggregate (LWA) mortar skin layer for use in sandwich concrete composite. The first phase of the research was focused on the development of the LWA mortar while the subsequent phase of work dealt with assessing the performance of the resulting sandwich concrete composite. In phase 1 of the investigation, it was found that mortar incorporating calcium aluminate cement (CAC) as binder and lightweight expanded clay aggregate (LECA) as fine aggregate had the best resistance towards high temperature of 1000 °C. The developed mortar along with basalt fibre mesh were used to form textile reinforced concrete (TRC) as skin layer which could still exhibit residual strength upon heated to high temperature. Furthermore, sandwich composite beam made of the TRC skin and aerated concrete as core had better flexural strength/weight ratio compared to that using conventional EPS foam as the core material. There was also no significant damage found on the sandwich concrete composite upon exposure to direct flame. The findings suggest that the development of the sandwich concrete composite is promising and further works can be explored to improve the performance.

An experimental study was performed to investigate the behaviour of angle shear connectors embedded in high strength concrete (HSC) slab. Eight push-out specimens were tested covering various geometries of angle shear connector. On top of the experimental study, the accuracy of the available equations to estimate the load capacities of angle connectors is also evaluated for the angles embedded in HSC. The results show inadequate ductility behaviour for the angle shear connectors embedded in HSC. Nonetheless, the angle connectors exhibited good behaviour in the case of strength degradation under cyclic loading. All specimens experienced the angle fracture type of failure and showed a very low strength degradation (0.1%–1.4%) when they were subjected to low cyclic fatigue loading. This study also concludes that the current available equations estimated the shear capacity of angle connectors embedded in HSC either are conservative or overestimate the ultimate capacity.

In this article, a particular Off-Centre braced system is examined. This bracing system consists of three members, where the diagonal member is not straight and it is connected to the corner of the frame by a third member. The out-of-straightness of the diagonal member introduces eccentricity to the system. This system improves the energy dissipation due to earthquake as well as its eccentricity allows architects to have more openings in the panel areas. In this regard, the location of brace elements connection point has significant effect on the stiffness of the system. In order to assess the influence of the connection position and other parameters such as cross section of brace elements and span/height ratio of the braced frame on the stiffness of the system, analytical equations have been developed. A new method based on Genetic algorithm (GA) to obtain the connection point is also proposed. The importance of elite individuals together with selection, mutation and crossover operator between populations are also examined. In order to achieve the best and practical location of the connection point, two equations for boundary conditions with regards to the opening dimensions are set in a computer model developed in MATLAB program. The results indicate that the stiffness decreases as the connection point moves closer to the corner of the frame. Additionally, the proposed method is proven to be efficient in determining the connection point due to its accuracy and minimal computational time required compare to conventional trial and error method.

Carbon fibre reinforced polymer (CFRP) has been used to strengthen steel members in bending and compression. There is a lack of understanding on behaviour of CFRP strengthened steel beams subject to torsion. This paper presents an experimental study on the behaviour of CFRP strengthened square hollow section (SHS) beams in pure torsion. A set of tests on CFRP strengthened steel specimens under torsion was carried out in which several different strengthening configurations were used. CFRP sheet wrapping consisted of different configurations including vertical, spiral, and reverse-spiral wrapping were used. The results showed that using CFRP could improve the elastic and plastic torsional strength of CFRP strengthened steel beam specimens. The number of layers of CFRP and the strengthening configurations were important factors for the improvement. Based on the measured values of the torsional moment at yielding and at ultimate, the corresponding twists, the torsional behavioural curves and the failure modes of the strengthened beam specimens, useful concluding remarks are presented.

Channel shear connectors are used to transfer longitudinal shear forces through the steel-concrete interface in composite beams. Angle shear connectors without bottom flange compared to channel shear connectors could be cheaper and more economic by saving more steel material. This paper presents an experimental evaluation for comparison of the behaviour of channel and angel shear connectors under monotonic and fully reserved cyclic loading based on 16 push-out tests. The connection shear resistance, ductility and failure modes are presented and discussed. By comparing the channel and angle shear connectors, it was concluded that angle shear connectors showed 7.5-36.4% less shear strength than channel shear connectors under monotonic loading and 23.6-49.2% under fully reversed cyclic loading. Connector's fracture type of failure was experienced for both channel and angle connectors. After the failure, more cracking was observed in slabs with channels compared to slabs with angles. Furthermore, in despite of sufficient ductility for all channel connectors, angle connectors showed less ductility. The results indicate that the angle shear connector gave good behaviour in terms of the ultimate shear capacity; however, this type of connector cannot satisfy the ductility criteria imposed by some codes. In the end, the shear load capacities obtained from the experiments are compared with those suggested by the design codes.

This research investigates the effects of applying different bond lengths for Carbon Fibre Reinforced Polymer (CFRP) strips used in flexural strengthening of steel I-beams. Wide range of the structural parameters i.e. load bearing capacity, failure mode, strain on CFRP, strain on adhesive, strain on steel beam, lateral deformation, and vertical deflection were investigated. Both numerical and experimental studies were employed. To simulate the specimens, ANSYS software in three dimensional (3D) modelling case and non-linear analysis method was utilized. In the experimental test, four-point bending method with static gradual loading was applied. Results indicate that using shorter CFRP bond lengths caused brittle behaviour, and applying longer CFRP bond lengths resulted in more flexible behaviour. Using different CFRP bond lengths affected the whole structural behaviours of the strengthened beams.

This paper reports the experimental and numerical investigations on the Carbon Fibre Reinforced Polymer (CFRP) failure analysis and structural behaviour of the CFRP flexural strengthened steel I-beams. Understanding the CFRP failure modes is useful to find solutions for preventing or retarding the failures. One non-strengthened control beam and twelve strengthened beams using different types and dimensions of CFRP strips in both experimental test and simulation modelling studies were investigated. In the experimental test, four-point bending method with static gradual loading was applied. To simulate the specimens, the ANSYS software in full three dimensional (3D) modelling case and non-linear analysis method was utilized. The results show the CFRP failure modes used in flexural strengthening of steel I-beams include below point load splitting (BS), below point load debonding (BD), end delamination (EDL), and end debonding (ED). The occurrences and sequences of CFRP failure modes depended on the strengthening schedule. The structural performance of the CFRP strengthened steel beams also varied according to the strengthening specifications investigated in this research.

In this paper, a method based on genetic algorithm is proposed for determining the optimum connection point with the highest lateral buckling load in the Off-Centre bracing system. This type of bracing system is mostly used in seismic areas and it allows architects to have more openings in the panel area. In this system, the non-straight diagonal member introduces eccentricity to the system and is connected to the corner of the frame by a third member. In designing this system, designers often use “trial and error” to locate the connection point of the brace elements considering various parameters affecting the design such as opening and frame dimensions, cross sectional areas of brace elements and the location of the brace element connection. Hence, finding the best connection point with maximum lateral buckling load can be problematic by the conventional methods. To demonstrate the effectiveness of the proposed GA method, examples with different frame specifications were presented.

In this paper, a nonlinear model is developed using the component method in order to represent the response of steel connections under various loading conditions and temperature variations. The model is capable of depicting the behaviour of a number of typical connection types including endplate forms (extended and flush) and angle configurations (double web, top and seat, and combined top-seat-web) in both steel and composite framed structures. The implementation is undertaken within the finite element program ADAPTIC, which accounts for material and geometric nonlinearities. Verification of the proposed connection model is carried out by comparing analytical simulations with available results of isolated joint tests for the ambient case, and isolated joint as well as sub-frame tests for elevated temperature conditions. The findings illustrate the reliability and efficiency of the proposed model in capturing the stiffness and strength properties of connections, hence highlighting the adequacy of the component approach in simulating the overall joint behaviour at elevated temperature.