Diagonal Braces Research Articles

Vibration control systems in a building prototype: Application of SMA coil springs in diagonal bracing and TMD

The growing concern with the efficiency and reliability of civil structures that are slim, flexible and highly vulnerable to earthquakes, side winds and impacts can be addressed with the use of smart materials. Among the available techniques, passive control stands out due to its low cost, low maintenance, and no need for an external energy source. In this sense, this work proposes the incorporation of NiTi superelastic SMA springs in a diagonal bracing arrangement and as a secondary device in a Tuned Mass Damper (TMD) to improve the passive vibration control of a 3-DOF building prototype. The study compares the efficiency of the proposed control systems through the modal analysis of the structure under scenarios combining different control types (diagonal bracing or TMD), vibration types (impulse excited or base-forced) and passive attenuation (with or without SMA springs). It was concluded that the length of the SMA spring attenuators has a direct influence on the control capacity, with the shorter springs providing a higher attenuation efficiency, as they generate greater mechanical hysteresis and dissipate more mechanical energy, while adding less mass to the structure. In terms of the amplitudes reached in the experimental modal analysis, the TMD with the SMA springs as a secondary device was the most efficient technique, allowing reductions of up to 74% in impulse excitation and 44% in forced vibration. In terms of added mass, TMD also proved to be more effective, reducing about 63% of NiTi SMA material in impulse excitation and 73% in forced vibration, when compared to diagonal bracing.

Performance Comparison of PEB Structure for Lateral Loads Using Different Bracing Systems

:The main objective of this project is to analyse & study the comparative performance of PEB structure with and without bracings such as X, V, Inverted V, Forward Diagonal Bracing, Backward Diagonal Bracing, K Bracing using Staad Pro V8i software. In earthquake zone the displacement and deflections of the structures will be more so to have more stiffness to the structure bracings are provided, hence this study compares the structures results with various bracings to find the best structure for lateral loads. All the considered structures have been subjected to various loads such as dead loads, live loads, earthquake loads. This study is mainly based on Static Equivalent Method of Analysis. Analysis was done as per IS:1893-2016. The results provide good evidence about the various parameters and show their performance on different conditions of the structure. For the obtained results we will check and conclude the best performing structure among all the other considered structure.

Safety and stability analysis of variable cross-section disc-buckle type steel pipe high support system

In order to solve the problems of poor safety and difficult determination of construction scheme in the construction process of variable cross-section disc-buckle type steel pipe high support system, based on the stress state of the normal working of the disc-buckle type formwork support, the stability bearing capacity of vertical poles under three working conditions of central pole, side pole and corner pole were experimentally carried out, and the correctness were verified by comparing with the results of the experiment and finite element analysis. Based on the verified finite element model and the characteristics of semi-rigid connection joints, the first-order buckling mode and nonlinear buckling analysis of the stability bearing capacity of the variable cross-section disc-buckle type steel pipe high support system were carried out in the construction period with special structure in practical engineering, the stability bearing capacity and deformation law of the variable cross-section disc-buckle type steel pipe high support system in the construction process were mastered. Through parametric analysis of the influencing factors such as the joint bending stiffness, the setting parameters and the initial imperfections, the influence law of the relevant parameters on the overall stability of the variable cross-section disc-buckle type steel pipe high support system was grasped. The results showed that the corner poles at the higher variable section and the lower variable section of the weak stiffness direction support system were prone to instability and failure. The overall stability bearing capacity was mainly affected by the lift height. The vertical diagonal bracing plays an important role in improving the overall stability, the larger the lift height was, the more obvious the improvement was. The overall stability bearing capacity decreases with increasing top extension length, and the top extension length should be controlled within 0.45 m. When the extension length of the top was greater than 0.45 m, the initial imperfection cannot control the overall stability bearing capacity, and the overall structural stability bearing capacity was determined by the buckling behavior of the top vertical pole. When the joint bending stiffness was greater than 2.0 K, the stability bearing capacity does not change. The higher the support system was, the smaller the influence of joint bending stiffness on the overall stability was.

Investigation on progressive collapse resistance of prestressed concrete frames with infilled walls

The finite element numerical model of prestressed concrete frames with infilled walls (IW-PC frame) is established to investigate the progressive collapse resistance under the failure of middle column. The simulation of infilled walls adopts the equivalent three-strut diagonal bracing model. The method of node coupling is adopted in the simulation of prestressed tendons Then the pushdown analysis of the structure is carried out. Meanwhile, the effects of the parameters of infilled walls and prestressed tendons on the compression arch action and catenary action are studied. The results show that the infilled walls greatly improve the anti-collapse bearing capacity of IW-PC frame. They enable beams to reach peak loads in advance, and transform the axial force of beam and prestressed tendons in advance. It is more conducive to make the prestressed tendons fully stressed, so that the structure can enter the catenary action in advance, thereby improving the bearing capacity.

Study and Behaviour of Seismic Load on Soft Storey Building Using Diagonal Bracing with Visco Elastic Damper

Study and Behaviour of Seismic Load on Soft Storey Building Using Diagonal Bracing with Visco Elastic Damper

Numerical modeling on shear performance of braced cold-formed steel composite walls

In this paper, the specific influence of diagonal braces on the hysteretic behaviors, including lateral stiffness, yield load, and load-bearing capacity, of braced composite cold-formed steel (CFS) walls have been investigated through the combination of previous experiment results and numerical analysis. A detailed modeling method using connector function in ABAQUS for simulating single screw connection has been introduced. Furthermore, the finite element models based on experimental specimens have been constructed, an excellent match of finite element analysis and experimental results are yielded to prepare for parametric analysis; five significant parameters, vertical load, panel splice type, screw spacing, section thickness of end studs, and diagonal braces, were considered in parametric analysis to in-depth investigate the hysteretic behavior of walls. Finally, some valued conclusions expected to be benefited engineering applications have been summarized.

Seismic performance of bolted connection between H-section beam and SST column welded with inclined braces

To improve the construction efficiency and achieve a rigid connection under design load, an innovative H-section beam-to-square steel tubular (SST) column bolted connection with inclined braces is proposed. The innovative bolted joint can realize bolted assembly between beam and column as well as between column and column, and it exhibits satisfactory stiffness and strength under earthquake with few bolts. Three groups of beam-column bolted joints with different types of inclined braces were designed, and tests and finite element analysis (FEA) were implemented under cyclic loading. The mechanical behaviour, deformation process, failure modes, and energy dissipation of all specimens were observed, and the effect of the type and length of inclined brace on seismic behaviour of joints was analyzed. The results showed that all specimens exhibited satisfactory ductility, plastic deformation capacity and energy-dissipation capacity. All tested joints with inclined braces showed failure mode of severe local buckling of beam section outside the connecting area, and the strength, stiffness and energy dissipation capacity of bolted joints with inclined braces were significantly improved. The joints with an H-shaped brace dissipate more energy than those with a channel brace, particularly when the web of the H-shaped brace is perpendicular to the beam web. Furthermore, the strength, stiffness and energy dissipation capacity of innovative joints with long diagonal braces are higher than those with short diagonal braces. On the basis of the test results and numerical analysis, simplified calculations for the slip resistance, yield resistance and ultimate resistance of the bolted joints with inclined braces are proposed and validated against tests.

Experimental assessment on aseismic capacity of a perimeter diagrid concrete core structure: Shake table tests

Perimeter diagrid concrete core (PDCC) is a structural system used for high-rise building applications. Quantifying their seismic safety is of interest to owners and decision makers due to the lack of the comprehensive understanding of the seismic performance of the high-rise PDCC structure. To systematically evaluate the seismic performance, a 36-story PDCC structure has been assessed using 1/20 scaled shake table tests. In addition, a detailed nonlinear finite element model (FEM) of the PDCC structure was built for comparison and analysis with the shaking table test. The damage to the perimeter diagrid bracings, the RC structural walls, the diagonal beam, under earthquake excitations have been assessed and discussed systematically based on the experimental and numerical results. The analysis result shows that the PDCC structure has a high performance under the earthquake load that can be used as an efficient seismic force-resisting system. Under the action of horizontal earthquakes, the axial force of the diagonal braces on the same floor varies greatly, and the axial force of the diagonal brace is related to the number of other diagonal braces on its axis. In terms of seismic damage to the perimeter diagonal braces, the most severe seismic damage is concentrated in the diagonal braces with higher axial forces, while the damage to other diagonal braces with smaller axial forces is less severe. And the seismic damage of diagonal bracing has a tendency to expand to other surrounding diagonal braces.

Optimum sizing design of steel frame structures through maximum energy dissipation of friction dampers under seismic excitations

This paper focuses on optimum sizing design of steel frame structures equipped with friction dampers (FDs) in order to prevent the vulnerable effect of an earthquake. The fundamental concept is to maximize the energy dissipation of implemented FDs under different seismic excitations. The FDs utilized as passive energy dissipation devices in a steel structure increase the energy dissipation capacity of the structure by decreasing the seismic demand during an earthquake. In this context, the Pall friction dampers (PFDs) are implemented as diagonal damped brace members in investigated structures. Three different earthquake records (Kobe, Kocaeli-Duzce, Erzincan) are utilized to acquire nonlinear dynamic responses of the steel frame structures through time-history analyses. The open application programming interface (OAPI) functions are used to integrate a finite element modelling based structural analysis program, SAP2000, with a design optimization algorithm encoded in MATLAB for achieving the exact structural behaviours by synchronously data transferring. As an optimizer, one of the recent nature-inspired metaheuristic techniques, so-called Grey Wolf (GW) algorithm is used. Initially, under effect of seismic excitations, the steel frame structures are optimally sized for attaining minimum design weights without implementing the PFD elements by subjecting only strength, displacement, drift, and geometric structural design constraints taken from AISC-LRFD practice code provisions. Afterward, in order for optimally modelling the PFD elements, the frames are equipped with PFDs to calculate optimum yield strengths that is defined as slip load of a PFD. To do so, the GW algorithm ensures the maximizing of the dissipated energy and controls the yield strengths between the stories since the shear force due to the earthquake increases towards the base of the structure. Eventually, the provisions-based sizing design optimizations of the steel frame structures equipped with optimally modelled PFD elements are conducted under seismic excitations for conclusive evaluations.

Experimental and Numerical Study of Pyramidal Steel Damper for Use in Frames with Diagonal Bracing

Experimental and Numerical Study of Pyramidal Steel Damper for Use in Frames with Diagonal Bracing

Experimental investigation of lateral resistance of CFS walls with rigid diagonal bracings

In this study, monotonic and reversed-cyclic loading tests were conducted on six diagonally reinforced cold-formed steel (CFS) shear walls sheathed with a gypsum board (GYP) and a magnesium crystal board (MCB), respectively, to evaluate the effects of sheathing panels and different types of diagonal bracings on the shear capacity, lateral stiffness, ductility, and energy dissipation capacity of CFS shear walls. The results revealed that the stiffness of the skeleton, the sheathing material, the performance of the screw connections, and the construction of the splice of the wall panels have a distinct effect on the shear performance of the wall. The cooperative work effect of the rigid and strap bracings was excellent, and the ultimate strength and lateral stiffness of the wall were effectively improved by using an extra steel strap bracing. The shear performance of the wall sheathed with the MCB was higher than that of the wall sheathed with the GYP. When a flat steel strap was used to connect the panel splices, the torsion of the flat steel strap reduced the overall performance of the wall panels. This should be considered in practical engineering applications.

Optimization of Fluid Viscous Damper Diagonal & Combined Bracing Arrangement in G+9 RCC Structure

earthquake event is changeable by nature, which has the capacity make devastating operational damage to a structure and collapse in due course which leads the huge loss of life and huge structure property loss. Because of this, much realization has initiated by many researchers for the progress of structural rheostat techniques such as passive controlling and active controlling system which are associated in the systems of Tuned Mass Damper, Fluid Viscous Dampers, Base Isolation inhibiters etc. In this study an experimentation has been carried by in view of G+9 reinforced concrete structure with in the proliferation of quake analysis in SAP-2000. The G+9 RCC structure has been analyzed by means of the connection of fluid viscous dampers situated at numerous patterns in two various systems such as diagonal bracing and combined bracing system by a total of 30 types has been espoused by trial based in various stimulating patterns. The efficiency of that analyzed structural models had better be clearly pragmatic by means of the resultant structural performances, for instance lateral displacement, energy dissipation, storey drift and base response etc. The finest optimum arrangement of fluid viscous dampers had recommended to use for seismic response resistant structure for vibrating control system.

Numerical Study on the Seismic Behavior of Eccentrically Braced Composite Frames with a Vertical Low-Yield-Point Steel Shear Link

An eccentrically braced composite frame with a low-yield-point (LYP) steel shear link is an efficient energy dissipation system that exhibits good mechanical properties. However, existing experimental studies have not fully demonstrated the superiority and applicability of the structural system. We present a structural mechanics and finite element model analysis of an eccentrically braced composite frame with a vertical shear link. The effect of the design parameters on the seismic performance of the structure is analyzed. First, a theoretical model of the mechanics of the structural system is established to provide a comprehensive description of the key parameters. Then, a finite element model is developed using the computer program ABAQUS to analyze the mechanical and energy dissipation mechanisms. Finally, the beam-to-column stiffness ratio, shear link web thickness, shear link web width and length, and diagonal brace stiffness are analyzed to determine their effects on the mechanical properties of the structural system. Furthermore, some design parameter values are suggested.

Effect of Bracings on the Behaviour of Industrial Buildings with Different Framing Configuration Subjected to Wind Load

Abstract: Steel structures are the best and smartest choice for industrial building construction, mainly because of their capability of creating large spans at lower costs. Usually, a different frame configuration along with effect of bracings has an effect on the behaviour of industrial buildings under wind load, along with PEB, truss, inclined, flat, curved roof. The methodology followed in PEBs is purely composite not only because of quality in pre-fabrication and pre-designing but also because of light weight outcome and economic sounding factor. In present study, Staad Pro is used for designing different sections such as k bracing, X bracing, Diagonal bracing and V bracing. The most economic truss chord sections are used for the designing of industrial building. So, the industrial buildings are designed for wind analysis with various bracings such as V bracing, X- bracing, k- bracing and diagonal bracing. Therefore, the most optimized structure is further compared to the PEB structure with the same parameters

A Multidisciplinary Computational Framework for Topology Optimisation of Offshore Helidecks

Maintaining offshore steel structures is challenging and not environmentally friendly due to the frequent visits for inspection and repairs. Some offshore lighthouses are equipped with carbon steel helidecks fixed onto their lantern galleries in the 1970s to provide easy and safe access to maintenance staff and inspectors. Even though the helidecks supporting structures have maintained their integrity and are still functional in the offshore harsh environmental conditions, their inspection and maintenance remains a challenge due to the need of frequent visits which requires flying to the location of the lighthouse to bring the maintenance staff and equipment. We have developed a multidisciplinary computational framework to design new generation of aluminium helidecks for offshore lighthouses. We calculated the wind speed at the location of the Bishop Rock lighthouse based on the meteorological data, and the load distribution on the helideck due to such a wind condition, using computational fluid dynamic analysis. Then, we used the calculated wind load with other mechanical loads in the events of normal and emergency landings of a helicopter on this structure to find the best design configuration for this helideck. We generated a design space for different configurations of a beam structure and carried out, static, transient and buckling analysis to assess each case using finite element method. The selection criterion was set to find the structure with the minimum volume fraction and compliance while keeping the stress below the allowable stress. We found the structure with eight vertical and circumferential sections featuring two rows of diagonal bracing with one at the base and the other one at the third section from the base of the helideck was the optimum design for the considered loading in this work. This framework can be adopted for the design and optimisation of other offshore structures by other researchers and designers.

Study on Shearing Behavior of Circular Concrete-Filled CFRP (Carbon Fiber-Reinforced Plastics)-Steel Tube.

Concrete-filled CFRP steel tube (CF-CFRP-ST) structures often suffer from shear loading in practical engineering, such as joints with diagonal braces. To study the shear properties of CF-CFRP-ST, we take the concrete strength and the longitudinal CFRP layers as the main parameters, and static shear tests of overall 9 circular concrete-filled CFRP-steel tube (C-CF-CFRP-ST) and 3 circular concrete-filled steel tube (C-CFST) are carried out. The research is carried out from two aspects: experiment and finite element. The experimental results show that the shear loading-displacement curves of the specimens can be divided into elastic stage, strengthening stage, and softening stage. The increases of the strength of the concrete and the layers of the transverse CFRP can both enhance the shearing load carrying capacity of the specimen. With the increase of concrete strength, there is no obvious change in the shape of the shear stress-shear strain curves of the specimens, and the shear stress and the stiffness of the curve in the elastic stage of the specimen are slightly increased. The shear loading-displacement curves of the specimens are simulated by using finite element software ABAQUS and it is found that the predicted results agree reasonably well with the test results. Then, the whole process of loading and the parameters of the main influencing factors are analyzed. Finally, the calculation equation of CFRP concrete-filled steel tubular shear capacity is established.

Lateral Behavior of Masonry-Infilled Wood Frames with Wood Diagonal Bracings of Different Forms

Lateral Behavior of Masonry-Infilled Wood Frames with Wood Diagonal Bracings of Different Forms

Comparative Analysis between Various Types of Bracings for Steel Building in Seismic Zones

Abstract: In this research paper we are preparing a relative report on a G+13 tall structure. In this structure we will contrast exposed casing and edges having various types of bracings at the corners. A three dimensional structure is taken, 13 stories is taken with story tallness of 3m. The bars and segments are intended to withstand dead and live load only. Seismic tremor loads are taken by bracings. The bracings are given just on the fringe sections. Here auxiliary displaying and examination is finished utilizing investigation programming Etabs which is a limited component based programming apparatus. A tall structure will be analyzed for seismic loading corresponding to various seismic zones. Effectiveness of bracings in reducing lateral displacements and their efficiencies during the earthquake is to be investigated. So the objective is to do comparative analysis between symmetrical G+13 storey RCC building with bracings and similar building without the bracings using commercially available software. Bracing play important role in keeping structure stable. Earthquake produces inertial forces in structure. X-bracing system has shown good results when it comes to reducing lateral displacements. As much as 26% decrease in lateral displacements in Z-Direction and up to 53% reduction in lateral displacements along X-direction is observed. But X-bracing arrangement shows most increase in value of Maximum bending moment (24.86%) and support reactions (30%).Base shear values are same in both directions. Since number of bracings along X-directions were more, bracings shown good performance in lateral displacements along X-axes. Diagonal bracing shows overall good performance considering Lateral displacements (45.58%), Support reactions (26.77%), and maximum bending moment (14.16%).Weight of the structure remains almost same. Not more than 2 percent change in weights of structure. Since base shear is dependent on weight, base shear also remain similar. Keywords: Comparative Analysis, Bracings, RC Building, Seismic Zones

Adding composite truss to improve mechanical properties of reinforced concrete T-girder bridge

To solve the problem of insufficient transverse connection of T-girder bridges, this paper investigated the strengthening method of two composite trusses symmetrically installed in mid-span. The composite truss included two top plates, four diagonal braces, and one horizontal brace. An experimental investigation was carried out to study the mechanical properties of reinforced concrete T-girder using single-point loading method under four load cases. The experimental results showed that the maximum transverse stiffness of T-girder specimens strengthened with composite trusses improved by 12.4% compared with control beams. Simultaneously, it had an excellent restraining effect on the cracks development. The maximum percentage decrease in the deflection corresponding to the maximum load when the reinforced concrete T-girder strengthened with composite trusses over the control beam of up to 39.7 was observed. In addition, the load transverse distribution coefficient was investigated according to rigid-jointed slab (girder) method. The composite trusses were chosen as intermediate diaphragm to calculate moment of inertia. The analytical model was in an accurate with the experimental result under the same loading condition. The optimize spacing of composite trusses was given from 600 mm ( L/10) to 1200 mm ( L/5), and thickness of top plate was 30 mm when the load transverse distribution coefficient was homogeneously distributed. Finally, a three-dimensional finite element model was used to evaluate the effectiveness of composite trusses.

Bracing frameworks consisting of parallelograms

A rectangle in the plane can be continuously deformed preserving its edge lengths, but adding a diagonal brace prevents such a deformation. Bolker and Crapo characterized combinatorially which choices of braces make a grid of squares infinitesimally rigid using a bracing graph: a bipartite graph whose vertices are the columns and rows of the grid, and a row and column are adjacent if and only if they meet at a braced square. Duarte and Francis generalized the notion of the bracing graph to rhombic carpets, proved that the connectivity of the bracing graph implies rigidity and stated the other implication without proof. Nagy Kem gives the equivalence in the infinitesimal setting. We consider continuous deformations of braced frameworks consisting of a graph from a more general class and its placement in the plane such that every 4-cycle forms a parallelogram. We show that rigidity of such a braced framework is equivalent to the non-existence of a special edge coloring, which is in turn equivalent to the corresponding bracing graph being connected.