Search

Civil infrastructures are vulnerable to catastrophic failures when exceeding the limit loading, requiring a reliable structural control mechanism, such as bracing systems, to enhance the integrity and stability of the structure. Bracing systems improve the performance of the structures by increasing the stiffness/strength of structures, the damping coefficient, and/or the energy absorption capacity. However, the functionality of these bracing systems is not controllable and may be altered after strong seismic events. Recently, the smart bracing systems based on multifunctional materials, particularly the shape memory alloy (SMA) and the magnetorheological fluid (MRF) have been developed. The superelasticity properties of SMA give the capability of recovering the original state after remarkable deformation. Furthermore, the SMA dissipates the energy of the applied load in the loading-unloading mechanism. The viscosity of MRF is variable and depends on the intensity of the applied magnetic fields. In the present study, a state-of-art hybrid SMA-MRF-based core bracing system is designed and in-house fabricated to enhance the structural behavior of the bracing system, including energy dissipation capacity and equivalent damping coefficient. Experimental tests have been conducted to illustrate the functionality of the system and the benefits of the SMA and the MRF systems. Finally, the seismic performance of the three-, six- and nine-story buildings equipped with the proposed SMA-MRF damping system is numerically assessed using nonlinear response history analyses. The results reveal that the proposed damping system significantly improves the seismic performance of the archetype buildings.

This study presents cyclic performance of a new bracing scheme using circular or elliptic bracing elements named OGrid for damage mitigation in structures subjected to earthquake excitations. To evaluate the seismic properties of this bracing system, an experimental analysis was performed on the OGrid bracing frame subjected to cyclic loading. Results showed that this bracing system has stable hysteretic behavior, a good range of ductility and high-energy dissipation capability. Because of the geometry of the proposed system, buckling has been not occurred and consequently, reduction of energy dissipation capacity has been not observed. Moreover, due to the high degree of indeterminacy of the proposed system, it showed appropriate stiffness after the formation of plastic hinges.

This study investigates the behavior of simple and continuous span steel box girder bridges after various damage scenarios, including bracing failure and girder fracture, and develops a non-contact bridge health monitoring technique based on the bridge dynamic responses. A series of field tests were conducted to study the feasibility of using non-contact sensors to capture the bridge dynamic responses. Moreover, detailed finite element models of the bridges were developed and validated using the field test and available experimental test results and were used to investigate the bridge failure mechanisms, maximum load-carrying capacity, alternative load paths, and dynamic responses. The bridge dynamic analysis after damage showed that bridge frequencies are sufficiently sensitive for identifying partial or full-depth girder fracture in the simple span bridges. However, these significant damages may cause very small changes in the natural frequencies of continuous span bridges. The results show a significant change in the mode shapes after damage in both simple and continuous span bridges. The mode shapes are sensitive enough to detect damage at the inflicted locations, in most cases with better resolution when compared to the frequency changes. The comparison of the intact and damaged bridge mode shapes indicates that damage at different locations along the bridge has different amplitude changes in the mode shape that could be used to localize the damage. Moreover, the analyses show that either the individual modal sensitivities or combined sensitivities are indicative for most locations throughout the span. The results also indicate a clear pattern of changes in the frequency and mode shape for each damage scenario that can be used to detect the damage type, severity, and location along the bridge.

This paper presents a structural modeling analysis of transmission towers with varied leg length combinations to examine the structural effects of unequal leg lengths. Power transmission towers in mountainous areas often use unequal leg lengths to accommodate the changing slope of the terrain. In this study, three types of 345 kV steel transmission towers with the D-type bracing system were considered as analytical examples to discuss the internal force distribution of the tower structure subjected to a load under a fully wired condition. Different tower structural types exhibit similar structural characteristics. The upper part of the force distribution of a tower structure is less affected by varied leg length configurations. The central parts affected by unequal leg lengths are the extension part and the tower leg component. Analytical results indicate the critical elements of tower structures with unequal leg lengths, which can serve as a valuable reference for disaster prevention and reduction. In this study, the primary elements of the towers were all under the permissible strength even with the leg length differences exceeding the current specifications. This implies that adjusting the regulation of leg length differences of a transmission tower with unequal leg lengths can serve as the basis for future research, highlighting the advantages of unequal leg length tower applications.

The damage suffered by elevated water tanks in previous seismic events can be generally attributed to poor performance of their frame-type supporting structure. It is pivotal to quantify the damage experienced by these tanks in damage states in order to ascertain their performance. In this study, the nonlinear response of frame-supported elevated water tanks is investigated using performance-based earthquake engineering method by utilizing the top drift of frame staging as the engineering demand parameter to evaluate its performance level. The influence of different patterns of reinforced concrete frame staging on the response of elevated water tanks was quantified using a fragility assessment. Finite element approach was employed and a total of nine models were developed representing the variation in staging patterns (basic, cross, and radial bracing configurations) and water-filling levels (empty, half-full, and full conditions) of the tanks and considering the fluid–structure interaction effect. Non-linear analyses were performed based on different seismic scenarios, and the seismic damage states from each staging pattern were evaluated. Fragility curves were generated according to three performance limit states specified in Vision 2000 and based on incremental dynamic analysis results for each staging pattern. Finally, the collapse margin ratios were quantified to evaluate the seismic safety margin against collapse of the elevated water tanks. From the analysis results, elevated water tanks having staging with cross and radial configurations showed better seismic performance compared to the basic configuration.

A new type of the y-shaped (Y) bracing system composed of three brace members arranged in a y-shaped geometry, frictional mechanism for energy dissipation and pre-compressed axial springs to provide the self-centering capability is developed and studied in this paper. To improve the seismic performance of the self-centered y-shaped (SCY) braced frame, it is designed such that the structural steel members including beam, columns and braces other than the self-centering member remain within the elastic range of steel material leading to protect the structural elements from damages under lateral loading. The mechanics of this system are explained, the equations governing its hysteretic responses are outlined and scaled validation tests of two frames with different geometries are conducted under the condition of reversed cycles of loading. The results of the two tested frames under the quasi static loading show that the SCY braced frame has stable hysteretic loops which ensure a constant level of energy dissipation. Analytical findings which were verified by the results of the experimental tests show that increasing the length of the self-centering element increases the force capacity of the SCY braced frame and the self-centering element experiences the greatest deformation under lateral loading in a specific length and angle.

Tower cranes, which are composed of a lattice structure, are mostly used to transport heavy materials and equipment in construction sites. The delicate structure of tower cranes and operating conditions make them very sensitive to dynamic excitation such as instant overload for any reason caused by transported material or wind and earthquake effect. This study was carried out for investigating the seismic performance of tower crane mast types with different kinds of bracing configurations. A program with respect to finite element method was written in MATLAB which is capable of meshing, modal analysis, and transient analysis. While nodal coordinates, material information, cross-section data, and the orientation of cross-section for each element in the structure and earthquake motion in the time domain are used for input data in the program, natural frequencies, mode shapes, mass participation factors of the structure and displacement, velocity and acceleration response of each node are obtained as output parameters. In this research, different types of mast frames were designed in terms of the most commonly used bracing configuration and were used in modal and transient analysis using two different earthquake motion inputs. The seismic performance of each mast type was determined in the time domain in terms of dynamic response characteristics.

Cold-formed steel (CFS) in construction delivers cost effectiveness and design flexibility. The instability failures of CFS Structural members significantly influences the failures of sheathing boards attached as an external cover. Therefore, present study experimentally examines the structural behavior of sheathing fastener connection in cold-formed steel wall frame. As a first attempt, strength and stiffness of the sheathing fastener connection is determined against the failure modes of point symmetric CFS wall frame studs. A new test setup has been developed to investigate the individual sheathing fastener failure modes. Parameters investigated include sheathing board types (varying thickness) and different dimensions of point-symmetric CFS studs. A total of forty-one individual fastener connection tests were carried out. The experimental investigation revealed that the fastener connection strength varies depending on the geometric dimensions of CFS stud and material composition of sheathing board. The result indicated that the bracing effect provided by plain gypsum board (fiber less) is insignificant and should not be considered for design. For sheathing boards with fiber composition, a generic parameter [ratio to design moment (Mx or My) to CFS stud depth (h)] is introduced to consider the structural bracing effect in CFS wall panel design. The limitations to consider the bracing effect of sheathing in the design of CFS wall frame studs are suggested for minor axis buckling and major axis buckling.

Superficial medial collateral ligament (sMCL) injury is common, but there are no in vivo studies describing the biomechanical efficacy of anatomic repair with internal bracing for grade 3 injuries.We used a porcine model to evaluate the efficacy of internal bracing using an artificial ligament for the early repair of acute, grade 3 sMCL injuries. Sixteen male castrated pigs were randomly assigned to a repair group: (1) anatomic repair using two suture anchors (Group R; n = 9) or (2) anatomic repair with internal bracing augmentation (Group IB; n = 7). The left knees were allocated to a sham surgery group (Group S; n = 16). All animals were sacrificed 4 weeks after surgery. The right and left femur-sMCL-tibia complexes were mounted on a tensile tester and stretched to failure using the same conditions as preconditioning at a cross-head speed of 50 mm/min. The internal bracing in Group IB was removed prior to the biomechanical testing. The failure mode and structural properties (upper yield load, maximum load, linear stiffness, and elongation at failure) were determined.Significant differences in failure mode were observed among the three groups. All sMCLs repaired with just the suture anchors (Group R) were avulsed from the femoral attachment, while most of the sMCLs repaired with internal bracing augmentation (Group IB) exhibited mid-substance tears (Group R vs Group IB, P = 0.0023). In Group S, 14 sMCLs were avulsed from the femoral attachment and two were avulsed from the tibial attachment (Group IB vs Group S, P 0.001). No significant difference was observed between Group R and Group S. There were no significant differences in the upper yield load, maximum load, linear stiffness, or elongation at failure among the groups.Loading of an artificial ligament for internal bracing did not result in better structural properties of the repaired sMCL itself.

The present study deals with a new system based on the combination of knee bracing frame and friction damper (KBFD). The friction damper used in the present study was constructed as a linear friction damper with long slotted holes. Four specimens of these dampers were tested under cyclic loading, and their load-displacement curves were outlined. Then, the numerical model was obtained by modeling the dampers in the finite element software validated with experimental results. By placing this type of damper in the numerical model of KBF frames, the parametric study of KBFD frames was performed under cyclic loads. The number of 42 frames were used in the present research, including six types of dampers in seven types of frames. Reports of analysis results could cover the hysteresis curves, initial and secant stiffness, frame resistance, dissipated energy and equivalent viscous cyclic damping coefficients. The results of analyses demonstrate the excellent seismic performance of the frames with the proposed configuration.

The observations from recent seismic events, shake table tests and large-scale experimental studies showed that mass timber structures demonstrate acceptable seismic performance. For these structures, the connectors are designed to demonstrate a ductile behaviour during the earthquake which is accompanied by inelastic deformation of the fasteners and crushing of the wood fibres. Despite the observed satisfactory seismic performance, the significant lateral stiffness degradation, as a result of irrecoverable damage in the connectors, makes these structures vulnerable to aftershocks and future events. Nowadays, a low damage seismic performance where the damage is localised in the replicable fuse and the inter-story drifts are capped within the desired range may be the preferred performance criteria for new timber buildings. This paper aims to assess the seismic performance of conventional mass timber buildings upgraded with resilient low damage braces. A design procedure for the strengthening of the lateral load resisting system is proposed and applied to a case study structure. The results showed that while the original structure failed to meet the defined seismic performance criteria, the strengthened structure demonstrated superior seismic performance. Furthermore, the lateral performance of the original and strengthened systems under subsequent earthquakes is investigated. The results of this study show the significant potential of the introduced bracing system for the strengthening of mass timber structures.

The goals of bracing in polio and postpolio are to optimize joint position and support weak muscles with the goal of reducing falls, reducing deformities, and optimizing energy conservation. Orthoses are primarily used in the lower extremities to optimize gait. Less frequently, upper extremity orthoses are required. Polio survivors are at increased risk of falls and injuries. Appropriate bracing and compliance with the prescribed device can prevent falls and injuries. The best orthotic results are often achieved with patients who have significant deficits but walk regularly, are well motivated, and are willing to adapt their gait for orthotic use.

During the past years, researchers have developed ideas to thoroughly investigate the behavior of structural bracing systems. Accordingly, one of these emerging systems is the Strong Back Bracing System by which the inter-story drifts are maintained constant to prevent the occurrence of failure. Hence, due to the importance of the soil-structure interaction (SSI) and the type of soil underlying the structure, the SSI needs to be taken into account for seismic-resistant design. Accordingly, this paper deals with the seismic behavior of the structures equipped with the Strong Back Bracing System considering the soil-structure interaction (SSI) under near and far-field earthquakes. In this respect, 3, 6 and 12-story structures resting on stiff and soft soil (soil type II and IV) have been analyzed. The results indicate that the ratio of the inter-story drift in the case of soft soil for all structures has increased by 11.67% under near-field records and subjected to the far-field motions, this ratio has raised by 7.7% for the 12-story building. Moreover, the ratio of the residual drift of the 3, 6, and 12-story structures under the average of near-field earthquakes, has decreased and increased by 8.52 and 36.02 in the case of stiff and soft soils, respectively.

This paper reports an experimental and theoretical investigation of gypsum-filled cold-formed steel (CFS) shear walls, for the purpose of addressing the estimation of lateral stiffness. A series of gypsum-filled CFS shear walls were tested under reversed cyclic loading. The infill walls declare the limit states in the failure of screw connections as well as the compressive failure of gypsum fillings. Besides, the shear performance of screw connections between CFS profiles and sheathings were also investigated by the local tests. The contributions of lateral stiffness under shear force mainly include the sheathings as stressed skins and the infill gypsum as bracing bars. A theoretical prediction of lateral stiffness for CFS infill walls was proposed based on superposition methods, which has a good agreement with the wall tests. Moreover, the shear stiffness of screw connections is required to determine the contribution of sheathings to lateral stiffness. Considering the extrusion deformation of sheathings along with the bending deformation of CFS profiles caused by the tilt of screws, a theoretical method was recommended to estimate the shear stiffness of screw connections.

This Technical Note aimed to present a surgical technique of ulnar collateral ligament (UCL) shoelace repair using suture anchors and double suture tapes in combination with internal bracing to correct UCL instability along with epiphyseal avulsion of the medial epicondyle in throwing athletes Skeletally immature throwing athletes playing baseball and softball are at a risk of sustaining medial epicondyle epiphyseal separation that can result in UCL instability, predisposing to elbow UCL disruption later. There are several surgical techniques that can restore elbow UCL function and stability. In cases where large fragments of the medial epicondyle are present in skeletally immature athletes, the residual bony fragment and the shortened, chronically injured UCL make surgical treatment quite challenging. Recent studies have shown that UCL repair with internal bracing can effectively treat acute UCL injury. However, this procedure is not ideal for restoring large disruption of the UCL such as fragmentation. Here, we present a surgical technique of UCL shoelace repair using suture anchors with double suture tapes in combination with internal bracing for correcting UCL instability concurrent with epiphyseal fragmentation of medial epicondyle in throwing athletes., Technique Video Video 1 This video shows the surgical technique of shoelace repair at the elbow, with internal bracing (IB), for treating ulnar collateral ligament (UCL) instability in throwing athletes. The patient was placed in supine position under general anesthesia. A 5 cm longitudinal skin incision was made over the medial epicondyle and UCL. The medial anterobrachial cutaneous nerve (MABCN) and ulnar nerve were identified and protected. A muscle split approach was made to expose the medial joint ligament capsule complexes associated with the UCL. To remove the fragment, the UCL was peeled off from the fragment. Then the remnants of the fragment were removed. A 4.75 mm BioComposite CorkScrew FT suture anchor was placed at the sublime tubercle. One suture tape was passed through both ends of the UCL in a shoelace-like fashion. This procedure was repeated 4 times with both limbs of FiberTapes to make a shoelace suture. After making a shoelace UCL suture, a SwiveLock with these FiberTapes was inserted into the tapped hole in the medial epicondyle, with the elbow flexed at 60°. Subsequently, the split fascia was closed with absorbable sutures.

This paper deals with the study, design and analysis of Buckling Restrained Bracings (BRB) and the also the optimized placings of BRB within the building so as the damage caused by seismic loadings is decreased to a bigger extent. For doing so an analytical study of a G + 7 commercial structure was meted out for the various parameters such as Maximum Story Drift, Maximum Story Displacement, Maximum Story Shear and Maximum Overturning Moment considering the frames without braces (conventional methods), with steel core braces and aluminum core braces (Al-BRB) by using E-tabs for finding the effect of each type of bracing on the parameters. Finally, the results were analyzed for the optimum use of BRB for seismic performance. Based upon the results, it is revealed that the use of steel core BRBs has increased the self – weight of the structure and hence the Light Weight BRB (LWBRB) can be used as an effective alternative for the Steel Core BRB. Ductile material such as Aluminum core can be used as a replacement for the steel core of the BRB. Due to reduced self – weight of the BRB as the section in the Buckling Restrained Braced Frame can be lighter in weight.

Structural bracing is normally used in steel structures to resist moments. In RC structures bracing is used as a retrofit technique to enhance the seismic performance of the building. But the scope of bracing as a concrete member is not as explored as concrete fails under tension. In my research project, I proposed a knee braced RC frame, where the bracing is provided as an RC member. Knee bracings are not so efficient compared to diagonal bracing, but it does resist moments and sway as well as allows passage through the frame. The objective of the project is to do an analytical model of a 2D RC frame; a bare frame; an infill frame; a knee braced frame. The lateral loading performance is compared within the three frames using cyclic loading. Displacement vs. time graph, load vs displacement graph is plotted for each frame to understand the performance of each frame under cyclic loading. The analytical work is done using finite element software.

In line with efforts made by researchers aiming to enhance ductility of the bracing systems, use of steel ring as an energy absorbing element with different pros and cons, has been evaluated in recent years. Hence, to alleviate drawbacks of this system, a novel bracing system including a circular yielding damper has been experimentally and numerically investigated in this paper. The main motivation to develop this system is to improve ductility, energy absorption and overcome some of the weaknesses of conventional systems. Moreover, this novel load-carrying system has a diamond-scheme in which there is a circular yielding damper and the damper and brace elements act indirectly with each other. To this end, an experimental specimen of the diamond-scheme bracing system with scale of 1 2 and pinned connections was built. Notably, the angle between the brace elements is taken equal to 15.6°. In the next step, the specimen was subjected to ATC-24 loading protocol and the experimental results were compared with the numerical outputs obtained from simulations using ABAQUS Software indicating a great agreement between them. Then, two types of diamond-scheme bracing including steel ring with various thicknesses as well as a link element with high rigidity substituted for the steel ring, were modelled in real-scale and placed inside a frame with two bays and one storey. Lastly, their performance was compared with that of the conventional bracing systems as well as the other similar previous studies. The results derived from experimental tests revealed that firstly, at the end of the testing process, all main brace elements remained elastic and only the steel ring has been damaged indicating the fact that the proposed system can properly distribute the induced loads in all components of the system (the steel ring works in shear and flexure and the brace elements are subjected to axial forces). Moreover, using a ring with load-carrying capacity of 3ton, a total capacity of nearly 27ton was achieved. It is noteworthy that the value of angle between brace elements plays a direct role in total capacity of the system. Numerical developments illustrated that as per increase in thickness of the ring (increase in the ring’s capacity), the capacity could raise up to 75% of that of a diagonal bracing system. Moreover, it was observed that energy absorption capacity of the diamond-scheme bracing system including the ring, is about 45% greater than that of the equivalent concentric brace. However, use of this system without presence of the ring (the case in which a link is present), despite having a behavior similar to that of the concentrically-braced frames (CBF), still suffers from drawbacks of the conventional braces as its braces act as the sacrificial element and incur buckling.

Gapped inclined bracing (GIB) is an innovative retrofit system for buildings with soft-story collapse mechanism. The system consists of a brace with gap element that activates before the structure approaches post-capping negative stiffness and collapse, providing supplemental plastic deformation and enhancing ductility of the system. This technique is also a resilient solution as the damage is controlled at the retrofitted soft-story, reducing the cost and time of repair. The paper presents a numerical study to verify the application of GIB systems for modern RC buildings, where masonry infill panels may be removed from lower stories due to functional requirements for more open spaces. Based on nonlinear static analysis, a novel and efficient design method is proposed to determine the GIB design parameters. To verify the performance of the retrofitting methodology, 12 configurations of RC moment frames with 4 and 8 stories are designed according to modern seismic codes and subjected to nonlinear static and incremental dynamic analyses. The results are then used to conduct fragility analysis to assess classical performance levels including immediate occupancy, life-safety, and collapse prevention. The results show that using the proposed design of GIB elements, the ultimate drift capacity corresponding to the collapse of soft-structures are increased by a factor of two. Also, the probability of collapse is reduced by 50% increase in the median collapse hazard intensity. These highlight significant improvements in the safety and resilience of buildings with soft-stories.

One of the new hybrid bracing systems which are recently proposed as a seismic retrofit of conventional concentrically braced frames (CBFs) is called the strongback system (SBS). In this system, by combining a substantially elastic vertical truss with an inelastic dissipating energy system, the occurrence of the soft-story mechanism is delayed or prevented. However, a generally accepted design method that ensures the elastic behavior of the SBS spine is not available. In fact, conventional code-based design methods underestimate the force demands in the SBS and cannot guarantee to achieve targeted performance. Here, a promising performance-based seismic design (PBSD) is used as a solution that is called yield frequency spectra (YFS). After the design system, its seismic performance is fairly compared to conventional bracing systems by using a series of nonlinear dynamic analysis. To this end, three six-story steel concentric brace frames in different configurations (chevron, Two-Story-X, and SBS) are designed using the YFS method. For performance evaluation purposes, the structures are modeled in OpenSees, and after two iterations, the design process was converged to the 98%-accurate solution. The median collapse intensity value of the YFS-based designed SBS increased by almost 20% compared to the prescriptive code-based designed one. The SBS also was found as the configuration with the highest ductility capacity and the lowest collapse probability.

A common and efficient type of concentrically braced frames in practice is the two-story X-braced (split-X) system. Most of the studies conducted on this bracing configuration, investigated the inelastic response of the frame under dynamic loading. While the mid-span gusset connection affects the frame response considerably, a limited number of studies have focused on this type of connection. In this paper, a finite element analysis model is developed for mid-span gusset connections. The model is first validated with experimental results obtained from a two-story X-braced frame tested under quasi-static cyclic loading in the literature. Next, the model is used to investigate the response of a mid-span, through gusset connection, which consists of a double channel beam and a through plate. Case study results show that the brace-intersected beam experiences about 37% lower stresses in the proposed frame compared to the conventional frame. The proposed connection is shown to achieve higher strength and better integrity than the conventional system. Parametric analyses are also conducted to address the shear demands and some geometrical design aspects in both proposed and conventional systems.

Cold-formed steel (CFS) shear walls filled with lightweight polymer material (LPM) is an efficient structural system which can provide high lateral stiffness and strength to resist lateral loads. Despite the significant advantages, the nonlinear behavior of the CFS shear wall filled with LPM is not fully understood. In this study, a total of seven full-scale CFS shear walls filled with LPM were tested under cyclic loads. The test parameters included different LPM types, X-shaped bracing configurations, sheathing types and wall openings. The failure modes hysteresis curves, envelope curves, feature values, ductility ratio, stiffness and energy dissipation of CFS shear wall with and without filling LPM were systematically compared. The experimental data reveled that this type of shear wall showed higher load carrying and energy dissipation capacities than CFS framing wall without LPM. To assist with the design of CFS shear walls filled with LPM, a modified strut-and-tie model was proposed. The modified strut-and-tie model was validated using the experimental data. The result demonstrates that the proposed model can be utilized to accurately estimate the load carrying capacity of CFS shear walls filled with LPM. The presented experimental and analytical results can be used by engineers to design CFS shear walls filled with LPM for earthquake engineering applications.

Background Many treatment options for osteoporotic vertebral fractures are available. However, limited and variable findings have been reported on the efficacy of the individual therapies. The objective of the present study was to systematically review the reported data for evidence of efficacy of spinal orthoses for osteoporotic vertebral fractures. Methods A systematic review of the PubMed database was performed. Two reviewers evaluated the studies found for eligibility. Randomized controlled trails (RCTs) and prospective nonrandomized, prospective single-arm, and retrospective comparative studies of the treatment of acute osteoporotic vertebral fractures with spinal orthoses were included. Results A total of 16 studies were included: 5 RCTs, 6 nonrandomized prospective comparative studies, 1 retrospective case-control study, and 4 prospective single-arm studies. Of the 16 studies, 4 (3 single-arm studies and 1 nonrandomized study) provided low-quality evidence that bracing, with or without bedrest, was safe. Also, 1 nonrandomized and 1 single-arm study provided low-quality evidence that bracing improved pain and disability. In addition, 4 studies demonstrated that the use of a rigid brace was equivalent to the use of a soft brace or no brace (2 high-quality RCTs, 2 nonrandomized studies, 1 low-quality RCT). Two nonrandomized and one case-control study demonstrated a benefit of kyphoplasty compared with bracing alone (all low quality). Two RCTs had provided low-quality evidence that bracing was superior to no brace and one nonrandomized study provided low-quality evidence that a dynamic brace was superior to rigid orthosis. Conclusions Limited evidence has suggested the safety of spinal orthoses for the treatment of osteoporotic compression fractures. At present, compelling evidence is not available to suggest that a rigid brace is superior to a soft brace or no brace. Kyphoplasty might be of benefit for select patients.

This cadaveric study investigated the biomechanical characteristics and stabilizing contribution of the bifurcate ligament using a multidirectional loading method and assessed the stabilizing effect of a brace after injury of the ligament. Eight freshly frozen cadaveric feet were tested for forefoot torque in inversion, eversion, adduction, and plantarflexion. Each band of the bifurcate ligament was transected sequentially, and the contribution of each portion of the ligament, as well as the stabilizing effects of the ankle brace, were examined. Stability decreased substantially after calcaneocuboid ligament transection for inversion and adduction loading. Bracing restored some stability, except for the adduction loading direction, for which it had only limited effect. The data indicate that inversion and adduction loading are strongly related to bifurcate ligament injury. The stabilizing effect of the ankle brace may have limited effectiveness for loads under adduction.

This paper aims to carry out an experimental and numerical investigation of the mechanical behavior of full-scale wooden 123 KV 13 L Cross-arm that used in transmission towers. Two points bending test was conducted to obtain load-deflection data of both scenarios, normal condition scenario and broken wire condition scenario. Balau wood was used to fabricate the whole structure of the cross-arm which includes main, tie and bracing members. When it comes to the normal condition, standard load 7.98 K N, with 8 organized steps with angle Θ = 54.2° at YZ plan from Y-axis were applied. while Fr = 16 K N with 16 organized steps with angle Θ = 12.6° at the horizontal plan, α = 17.57° at vertical plane was applied for the broken wire condition. Deflection values due to these loads were determined by using 25 dial gauges that installed on both main members and tie members. Load-deflection investigation of both X–Y plots was considered for the main members while the Load-deflection investigation of Y plot was considered for tie members. Experiments of load-deflection data were validated by conducting a simulation process of normal conditions. The simulation process was designated to the first point (at R,L 734 mm) on the main members in both directions X and Y-axis during the normal condition. The numerical results of simulation have proven that the experiments were confident 93%.

K-shaped bracing is one of the lateral load resisting systems used in Cold-Formed Steel structures. Recently, some researches have been conducted to obtain further information about the seismic performance of the CFS using K-shaped bracings under monotonic and cyclic loads. In this research, the seismic performance factor of this structural system is under study. To determine the proper value of this factor, a non-linear finite element model of this structural system is developed using OpenSees software, and the cyclic behavior of this model is verified with previous experimental results. Several structures designed in accordance with Iranian seismic code were modeled using the verified model, and incremental dynamic analysis is performed on these structures. The analysis was performed according to FEMA P695 procedures using a ground motion set consisting of 22 earthquake records. Eventually, the studies showed that the seismic performance factor of 2 is a proper value for the cold-formed steel frames with K-shaped bracings. Also, as another result, the increase in the number of stories and the site’s seismic risk will increase the structure’s collapse probability. Furthermore, the height limitation proposed by seismic codes for this system seems to be somewhat conservative and it can be concluded that usage of the K-shaped bracing system is possible for taller structures in zones with low seismicity risk. Finally, it can be concluded that the K-shaped bracings might not have a suitable performance due to ductility issues.

While conventional steel seismic resistant structural systems may provide sufficient safety for the occupants, generally they depend on damage in the selected structural members to resist severe earthquakes. Therefore, after such an event, there may be considerable economic loss and significant repairs followed by business downtime. In addition, the post-event residual displacement of the structure can compromise the post-disaster functionality of the building. Recent severe earthquakes in New Zealand have highlighted the problems with assessment and repair or replacement of buildings designed for controlled damage and have provided a strong motivation for researchers and engineers to start developing concepts and design methods for low damage self-centring systems. This paper proposes a step-by-step design procedure for steel braced frames with diagonal tension-only braces equipped with the innovative Resilient Slip Friction Joint (RSFJ) connections. The proposed procedure is used to design a 5-story steel structure with RSFJ tension-only x-braces to verify its efficiency and to demonstrate that the system can meet the ductility demand recommended by the standard. The numerical results showed that the proposed procedure could accurately predict the behaviour of the system and potentially can be used for low damage bracing systems with a flag-shaped load-deformation response.

Background Adolescent idiopathic scoliosis is a common condition affecting 2.5% of the general population. Vertebral body stapling was introduced as a method of fusionless growth modulation for the correction of moderate idiopathic scoliosis (Cobb angles of 20–40°), and was claimed to be more effective than bracing and less invasive than fusion. The aim of this study was to assess the effect of vertebral body stapling on the stiffness of a thoracic motion segment unit under moment controlled load, and to assess the vertebral structural damage caused by the staples. Methods Thoracic spine motion segments from 6 to 8 week old calves (n=14) were tested in flexion/extension, lateral bending, and axial rotation. The segments were tested un-instrumented, then a left anterolateral intervertebral Shape Memory Alloy (SMA) staple was inserted and the test was repeated. Data were collected from the tenth load cycle of each sequence and stiffness was calculated. The staples were carefully removed and the segments were studied with micro-computed tomography to assess physical damage to the bony structure. Visual assessment of the vertebral bone structure on micro-CT was performed. Findings There was no change in motion segment stiffness in flexion/extension nor in axial rotation. There was a reduction in stiffness in lateral bending with 30% reduction bending away from the staple and 12% reduction bending towards the staple. Micro-CT showed physeal damage in all the specimens. Interpretation Intervertebral stapling using SMA staples cause a reduction in spine stiffness in lateral bending. They also cause damage to the endplate epiphyses.

This paper examines a newly developed seismic-force-resisting system technically known as Strongback. To achieve improved seismic performance, this system combines characteristics of a traditional concentric braced frame (CBF) with a mast to form a hybrid system; the strongback system aims to promote uniform story drifts over the height of a structure. In seismically prone areas, structures are not always subjected to a single earthquake and they are likely to experience seismic events sequentially. Accordingly, this paper deals with design method as well as the nonlinear dynamic behavior of structures equipped with strongback system (SBS). In this regard, three buildings with 3, 6 and 12 stories configured in three diverse forms at the intersection of the braces to the beam were studied. For the sake of dynamic analysis, different earthquake records and 18 various consecutive seismic scenarios were accounted for. Finally, it is concluded that SBS can effectively deconcentrate deformations using the proposed design strategy and prevent the occurrence of the soft-story phenomenon.

The main issue that may be encountered during brace treatment of idiopathic scoliosis is the patient's compliance. While compliance with full-time brace treatment has been well documented, compliance with night-time brace treatment has not. The main feature of night-time braces is their ability to overcorrect the scoliotic curvature, which could decrease compliance. The primary aim of this study was to evaluate objectively the compliance of patients with idiopathic scoliosis when undergoing treatment by means of a night-time overcorrection brace. Twenty patients with adolescent idiopathic scoliosis were prescribed treatment with an overcorrection brace for 8 h per night. Compliance was determined by the percentage of actual hours the brace was worn relative to the prescribed regimen. Compliance was measured during 1 year via a hidden temperature monitor embedded within the brace. Patients were informed that their compliance was monitored. The brace acceptance period and the full acceptance period were analysed, and correlations were measured. The average compliance (% wearing hours/prescribed regimen) was 90.7%; 45% of the participants met or exceeded the prescribed brace time. Three girls were lost to follow-up. The mean acceptance period was 22,8 days, and half of the patients succeeded in achieving the acceptance period in less than 7 days. The mean full acceptance period was 26,9 days. The acceptance period was significantly and negatively correlated with the mean wearing time (r = −0,61, P = 0,004). There was no correlation between the in-brace overcorrection and the wearing time. These results suggest that patients with an overcorrection night-time brace had good compliance. The overcorrection did not seem to influence compliance. The first weeks of treatment seemed to be crucial for treatment compliance.

Understanding of medial column biomechanics is paramount to a successful outcome in both conservative and surgical treatment. Dysfunctions of the dynamic stabilizers as well as the static stabilizers of the medial column play a role in pathomechanics. Conservative options for addressing the medial column include custom foot orthotics and bracing. Options for addressing the medial column surgically with the goal to restore a stable tripod configuration, include first tarsometatarsal joint arthrodesis, opening plantarflexory medial cuneiform osteotomy, and naviculocuneiform arthrodesis.

The castellated beam with different web openings are mostly employed in construction since last decade due to its higher load bearing capacity with the mass lower than its solid counterpart and also economical. Though numerous simulation and experimental analyses have been made on castellated beam, the study on understanding the nonlinear behavior are very meager. The present investigation focuses on understanding the nonlinear behavior of the solid beam – ISMB150 and IC225 castellated beam – without and without diagonal bracing across the opening and the effect of fillet radius arrangements. The finite element model developed is analyzed using Hyper works 2017 with Opti struct solver with 3D hexagonal mesh model. The load vs deflection nonlinear results show that the load bearing capability of castellated beam IC225 beam increases upto 1.28 times compared to the parent solid ISMB150 beam. On providing the lateral stiffeners, the load bearing capability increases upto 28% compared to the ISMB150 and 15% compared to IC225. Due to the presence of sharp corners of the opening it is prone to crack and fail hence attempt had been made to check the variation of fillet radius in the corner. The Von-mises stress distribution shows that the failure occurs due to Vierendeel mechanism with yield occurring on the flange but without any failure on the web. The finite element analysis results show that the ultimate strength can be increased on providing the stiffeners which also reduces the deflection. The provision of fillet radius at the corners of the web openings also serve in reduction of the stress concentrations at corners.

Structural fuses are sacrificial elements embedded in the structural members to localize potential failures within themselves. These replaceable segments are used to dissipate the energy of severe loads while preserving the integrity of the structure's major components. This paper presents an innovative Composite Buckling Restrained Fuse (CBRF) as a segment of a bracing element. CBRF with relatively small dimensions is a hysteretic damper with different performance in tension and compression. According to the typical difference of the bracing element capacities in tension and compression, the CBRF possess higher tensile strength than its compressive capacity. Utilizing tensile-only elements in this fuse with a new configuration improves the efficiency of the energy dissipation and eliminates the limitation of the tensile strength that exists in bracing members which contain ordinary ones. Key design parameters such as cross-sectional area and length of the fuse core are discussed theoretically. Six CBRF specimens with various dimensions and tensile-only elements were designed, tested and numerically modeled under cyclic loading to provide better insight into the fuse core and the encasing performance. The results indicated that the proposed structural fuse has a ductile behavior with maximum average core strain of 5.6% and sufficient tensile strength along with high energy absorption capacity.

Purpose Ligament bracing is a technique of suture reinforcement that can be used to augment lateral ulnar collateral ligament repair in the treatment of posterolateral rotatory instability of the elbow, thereby improving early stability of the repair. However, multiple failures of the ulnar anchor during implantation have been documented. We hypothesized that the use of a cortical button for ulnar fixation of the ligament brace would be biomechanically comparable to a suture anchor construct. Methods Sixteen elbows were tested with a materials testing machine. The intact, dissected, and repaired lateral collateral ligament complex was tested with a cyclic varus rotational torque of 0.5–3.5 Nm in 120°, 90°, 60°, and 30° elbow flexion . For the repair, the specimens were randomized into 2 groups: ulnar fixation of the ligament bracing using a suture anchor and ulnar fixation of the ligament bracing using a cortical button. The number of implant failures was documented. A load-to-failure protocol was conducted in 90° elbow flexion. Results Load to failure was comparable and was found to be 20.7 Nm in the suture anchor group and 21.8 Nm in the cortical button group. Laxity after ligament bracing did not differ significantly between suture anchor and cortical button fixation. Compared with the native ligament, the laxity was significantly reduced after ligament bracing. The failure mode was slippage of the suture tape through the humeral anchor in all cases. Additionally, the capitellum was damaged in 9 of 16 cases. Conclusions A cortical button for ulnar fixation of the ligament bracing was comparable with a suture anchor fixation with regard to biomechanical properties such as laxity and load to failure. Clinical relevance A cortical button fixation is less prone to failure of insertion. This would improve the implantation technique, while clinical results are expected to be comparable.

This paper presents the development of novel affordable steel-framed modular units for construction with enhanced overall (healthcare, structural, fire, and lightweight) performance, which ideally suits for emergency response situation, such as current covid-19 pandemic. The nature of quick response and well-prepared strategies are essential to cope with the demand of quicker construction for emergency response structures and if similar situation continues or arises in the future as well. Off-site oriented modular construction is ideal to provide these requirements at very short notice for emergencies. Modular units made of steel components are a leading choice due to the exceptional strength and rigidity for lightweight construction. A new weight optimisation procedure was developed for Cold-Formed Steel (CFS) joists in varying shapes of and results show that weight for per unit length of the joists can be reduced up to 24% without compromising structural capacity. This was verified with validated Finite Element (FE) models. In order to improve the faster jointing method, a novel cut and bend intra-module connection was also introduced. In addition, strap bracing is used for the lateral stability of steel-framed modular buildings. Modular breathing panels are proposed to be employed in corner post modules as sidewalls to improve the indoor air quality and reduce the spread of disease. Based on the comprehensive assessment and numerical results conceptual design of performance improved steel-framed corner post modular unit was proposed to offer short-to-medium (in response to emergencies), as well as long-term solutions for the construction industry.

Screw anchors are widely used in applications such as fastening base plates in steel and metal construction, formwork and bracing, structural steel applications, railings and handrails. At present, researchers and design engineers rely on the Concrete Capacity Design (CCD) method to predict the strength of screw anchors under the tensile loading as the only method available in literature. In CCD method, the underlying assumption is that the concrete cone and combined concrete cone and pull-out failure modes are the main failure mode for anchors, whereas, previous studies have demonstrated that pull-out is also a very common failure mode of screw anchors. In this paper, experimental results of more than 180 tests on one particular type of screw anchors are studied to better understand their behaviour under tensile loading. Experimental results are classified based on the observed failure modes. New equations are proposed to predict the tensile capacity of this particular type of screw anchors associated with each of the above mentioned dominant failure modes for the first time. The experimental results are compared with the predicted values by the CCD method and specifications provided by the anchor manufacturer. It is also shown that in majority of cases, the CCD method overestimates both the experimental results and the specifications given by the manufacturer.

Steel bracing systems are usually introduced to assure the structural stability and seismic resistance of steel storage pallet racks, whose height over the last years has increased more and more to improve warehouse efficiency. In the present paper, the axial response, under monotonic and cyclic load, of perforated cold-formed steel diagonals of concentric bracing systems is investigated through experimental tests. To satisfy the design and detailing rules required by the capacity design approach, such as the ratio between overstrength coefficients and the value of the non-dimensional slenderness, tested diagonals are equipped with additional holes at one end. Results of monotonic tests, under compression and tensile load, provide useful information about the influence of the number and shape of holes on the ultimate strength, ductility and buckling load of bracings. Cyclic tests highlight how the member slenderness and the class of its cross-section affect hysteresis loops and energy dissipation. Finally, some novel considerations are presented concerning the influence of the shape, dimensions and distance of additional holes, in addition to member geometrical features like the cross-section class, on the cyclic response of tested members. In the framework of the “Design Assisted by Testing”, results could be adopted for the capacity design of perforated concentric cold formed diagonal bracings as those adopted in steel storage pallet racks.

This paper investigated the structural robustness of steel-framed modular buildings based on the alternative load path method using LS-DYNA. The structural responses of a reference structure were first simulated to understand typical building motion, load redistribution mechanisms and failure modes after removal of a base corner module. Based on the reference scenario, a comprehensive parametric study was then carried out to investigate the effects of structural configuration (number of modules of each floor), module posts (wall thickness and number of supporting posts) and other features (inclusion of floor slab, longitudinal wall bracing, connection stiffness and connection capacity) on the structural responses of steel modular buildings. It was found that the collapse resistance of steel modular buildings could be improved with an increase in the number of modules per floor, the number and capacity of supporting posts, higher rotational stiffness and capacity of inter-module connections, and the use of longitudinal wall bracing. Consideration of floor slabs provided a more realistic description of collapse mechanisms, due to the slab-related contact interaction and diaphragm action. Also, the structure was more vulnerable to the removal of modules (or posts) near the end corner of a building.

The paper discusses the numerical analysis of all-steel buckling-restrained braces. These devices are designed to work in an inherently unstable regime, and their behavior is acutely sensitive both to any configuration detail in reality, and to any adopted parameter in their analysis. Their dissipative axial behavior can be reasonably well predicted by any suitable FEM model, if a good constitutive law is available. Nevertheless, it is shown here that an apparently accurate FEM calculation of the lateral contact forces, generated by the buckled core when it contacts the external containment profiles, produces results so sensitive to modelling details that they are practically devoid of an acceptable degree of accuracy. These observations might raise some doubts about the advisability of employing this type of bracing in normal engineering practice. In our viewpoint, a similar conclusion could be reached for any structural element designed to work in an unstable regime, unless the imperfections – of any type, including possible modelling details – could be explicitly taken into account, either parametrically or in a statistical way.

This study investigates the seismic performance of a newly developed self-centering bracing system using a novel experimental technique named as closed-loop dynamic (CLD) testing. The bracing, named piston-based self-centering (PBSC) apparatus, employs Ni-Ti superelastic shape memory alloy (SMA) bars inside a sleeve-piston assembly for its self-centering mechanism. During cyclic tension-compression loading, the SMA bars are only subjected to tension avoiding buckling and leading to flag-shaped symmetric force-deformation hysteresis. Initially, a braced frame building fitted with PBSC is seismically designed and the preliminary sizing of the brace is determined. For testing, considering the lab capability, the brace is fabricated at a reduced scale. The process of “Closed-loop dynamic testing” starts with the brace test (step 1) under strain-rate loading to characterize the numerical model parameters (step 2), which are then scaled-up as per similitude law and implemented in a finite element software, S-FRAME’s PBSC brace model (step 3). Then the braced frame building is analyzed under an earthquake (step 4) and the axial force-deformation response of the brace under consideration is captured (step 5). In order to further understand and validate the actual response of the brace under earthquake type loading, the axial deformation obtained from S-FRAME is scaled-down (step 6) and used as input parameters for testing the reduced scale brace (step 7). The obtained response (step 8) is further scaled-up and used to match the S-FRAME’s PBSC model for validation (step 9). Iterations from step 3 to step 9 will be required until the experimental and numerical results converge. Convergence criteria used for this validation include both the energy dissipation capacity and initial stiffness within 10% accuracy. Reasonable agreement between the numerical and experimental results is achieved in the closed-loop dynamic testing. The PBSC brace shows excellent self-centering capability under various earthquake loadings.

To study the fatigue and fracture behavior of I-shaped steel bracing members, numerical simulations based on OpenSees for 18 Q235 and 21 ST12 welded steel braces under constant-amplitude cyclic axial displacement were conducted. As the numerical results are consistent with experimental data, a representative strain, which is modified by correlative parameters (including slenderness ratio, width-to-thickness ratio, height-to-thickness ratio and yield stress) of the brace and calculated by corresponding equations, has been proposed as a new control parameter to predict the fracture life of bracing members under low-cycle fatigue loads. According to the good logarithmic—linear relationship between the representative strain and the fracture life, the predicted fracture lives of all specimens were almost always located within a safe scatter band of 1.5. Moreover, the miner method was used for calculating the cumulative damage of 39 bracing members. An allowable damage factor was discussed to assess the fatigue damage and to predict the fracture life under a variable-amplitude cyclic load. Then, a simulation of 5 single diagonal and 8 inverted-V braced frame tests was conducted. It was found that the predicted fracture lives of all these braced frames are very close to their true lives shown in tests and are mostly located within a safe scatter band of 1.5, indicating that the simulation can provide a relatively accurate evaluation on the fatigue performance. In addition, the damage distribution and damage development of the brace section in simulations are in good agreement with the failure mode in the physical tests, which can generally correspond to the cracking process and the complete fracture behavior of the bracing members.

To evaluate the effects of neoprene sleeves (NSs) and prophylactic knee braces (PKBs) on neuromuscular control and cutting agility.Markerless motion-capture technology tracked subjects (1) without a brace as a control (2) with NSs and (3) with PKBs during single-leg drop vertical jump (SLDVJ), single-leg squat (SLS), Y-excursion, and cutting movements. Movements were recorded five times per bracing condition in three different sessions.University laboratory.Ten healthy, active subjects (5 male, 5 female; age range, 22-26 years).Degrees of motion and time to completion.Use of NSs and PKBs reduced subjects' hip internal rotation in the loading phase of SLDVJ (p = 0.026, 0.02) and SLS (p = 0.005,0.001), reduced knee flexion in the loading phase of SLDVJ (p = 0.038,0.001), and reduced knee frontal plane abduction (FPA) with SLS (p = 0.015, 0.024) and Y-excursion (p = 0.002, 0.005) compared to control. Use of PKBs decreased subjects' hip internal rotation in the Y-excursion (p = 0.024) and reduced knee FPA in the SLDVJ loading phase (p = 0.014) compared to control. There was no difference in cutting agility for either group (p = 0.145, 0.347).Both NSs and PKBs positively impacted neuromuscular control without impacting cutting agility.

When selective pallet racks are allowed to rock in the cross-aisle direction during an earthquake, the uprights are subjected to short duration high axial forces at stomping. In this paper, the amplitude of the stomping force needed to compromise the upright's residual capacity is assessed for 59 configurations using nonlinear inelastic static and dynamic analyses. Parametric studies are performed to investigate the effects of upright length, bracing pitch, section slenderness, torsional restraints and multiple impulses on the residual capacity of an upright due to rocking. Uprights that fail in the flexural-torsional buckling mode perform better than those that fail by local-distortional buckling as the stomping causes permanent local-distortional deformations rather than sweep (torsional deformation). A rack upright that has a greater length, greater thickness and lower torsional restraint tends to have a higher residual capacity (relative to the undamaged capacity). A typical cold-formed steel rack upright can sustain a 0.1 s stomping force that is at least 15% greater than its static ultimate capacity without significant reduction in residual capacity. An implication is that an unanchored upright that survives an earthquake through rocking may double its storage load during the post-earthquake emergency period. The present shell element analysis results can be used to plan an experimental program for optimising the resilience of storage rack uprights against stomping.

Special concentric braced frames are provided in buildings located in severe seismic zones to resist earthquake loads. The seismic performance of these frames is mainly depend on the capacity of bracing in tension. However, the detailed studies are not available to find the optimal tensile capacity of such bracing to give the acceptable performance under severe earthquake. This paper presents the seismic performance of regular 6, 9, 12 and 15 storey special concentric X-braced frames in which tension bracings are designed for the lateral load of 100%, 70% and 60% of base shear. Demand to Capacity Ratio (DCR) is varied in beam and columns (0.4–0.7) and bracing (0.6–0.9) under design lateral loads. Pushover curves are developed to determine the strength and ductility of the frame for all the DCRs considered in the study. Column DCR of 0.4 and 0.5 is proven to be more effective with bracing DCR of 0.8 and 0.9 in terms of strength and ductility. It is also found that the displacement demand for the frames designed for 60% of the total base shear under maximum considered earthquake is within acceptable limit.

Behaviour of low rise cold-formed steel-framed residential structures when subject to lateral loading (e.g. wind and earthquake loads) is significantly influenced by both structural and non-structural elements. The ceiling is normally considered as a horizontal diaphragm for the distribution of such lateral loads to the bracing walls. In Australia, the ceiling diaphragm, in single and two storey cold-formed steel-framed houses, is made of plasterboard lining fixed to ceiling battens which in turn are screwed to the roof trusses. Determination of the stiffness and strength of the ceiling diaphragm is crucial for accurate distribution of the lateral load to the lateral resisting elements (e.g. bracing walls). This paper presents experimental results from tests of typical ceiling diaphragms. Further, a detailed finite element model is described which was validated against the experimental results. The model is capable of reproducing the initial stiffness, non-linear deformation and ultimate strength. The finding from this work would assist engineers in designing the lateral load resisting system for houses.

The objective of this work is to examine the bracing effect of sheathing boards in inhibiting the instability failure modes of cold-formed steel (CFS) studs in the wall panel construction. A development of accurate and robust sheathing braced design concepts for CFS wall panels will eliminate the need for additional lateral steel bracing, thereby leading to efficient use of construction materials. The current design method by the American Iron and Steel Institute lacks in accurately predicting the design strength of the sheathed CFS stud. Therefore, the current investigation endeavors to fill the gap by carrying out experiments that simulate the behavior of the CFS studs subjected to out-of-plane loading. A total of sixty-seven experiments were carried out with seven different sheathing board types and ten different CFS studs to accomplish the objective. The experiments were carried out using a newly devised test set-up that simulates the worst case failure mode of the sheathing board. The experimental results indicate that the strength, stiffness and failure modes of the sheathing boards vary depending on the following; (i) fiber composition and material properties of the sheathing board; (ii) dimensions of the CFS stud. In addition, the test results also indicated that the stiffness of the sheathing board against the pull-through failure was not influenced by the thickness of the sheathing boards. Based on the inferences (trend of sheathing stiffness and failure modes) from the test results, a new expression is formulated to determine the stiffness of the sheathing board on a function of the tensile modulus of the sheathing board (Es) and dimensions of the CFS stud (d/2). The validation study indicates that the new expression is accurate in terms of both statistical and design application.

This paper presents an experimental investigation followed by numerical modeling for cold-formed steel (CFS) shear wall sheathed by fiber-cement board (FCB) under monotonic lateral load. Afterwards a numerical parametric study was performed taking into consideration various factors affecting the system ductility. The response modification factor was estimated using Equal Energy Elastic-Plastic rule. The results showed that the screw connections between the FCB and the steel framing members are of significant impact on the nonlinear behavior of the system. Also, the X-strap bracing increases the lateral load capacity and the values of response reduction factors (R) of the sheathed CFS shear walls.

This paper presents an experimental investigation on sheathed cold-formed steel wall panels subjected to out-of-plane loading. The objective is to determine the two-sided gypsum sheathing effect on the design and behavior of the point-symmetric CFS studs. The design parameters such as global slenderness of the CFS stud, sheathing thickness and distance between the fasteners are varied, totaling twenty full-scale experiments that were tested under four-point bending. In general, the experimental results indicate that the gypsum sheathing board with a thickness of 15 mm and a fastener spacing of 150 mm hindered the occurrence of the biaxial bending of the point-symmetric CFS stud and led the CFS stud to reach its yield moment. To quantify the bracing effect of sheathing, the design predictions were carried out as per the current AISI report. The design results indicated that the design strength of a majority of the point-symmetric CFS studs can be drastically increased by the sheathing's bracing effect. However, few design results are unconservative compared to the experimental results which was confirmed by the reliability analysis as per AISI. Further investigation reveals that the current AISI design procedure requires significant modification with respect to the loading conditions and geometry of the CFS stud. In addition, the present study also discovered certain procedures to make the current sheathing braced design methods conservative and robust.