External Column Research Articles

An Innovative Technique for the Strengthening of RC Columns and Their Connections with Beams Using C-FRP ROPES

The application of the innovative C-FRP ropes for the strengthening of reinforced concrete columns is experimentally examined. Two real-scale specimens with the same geometrical characteristics and the same steel reinforcements were constructed for the needs of this investigation. The primary objective of the study is to investigate the efficacy of the use of C-FRP ropes as externally mounted reinforcement for the strengthening of deficient external columns. In this direction, (a) C-FRP ropes are applied as longitudinal reinforcement of the column for the increase in the flexural strength, (b) C-FRP ropes are applied as external confining stirrups in the critical end parts of the column for the improvement of the concrete strength and the development of local element ductility, and finally (c) C-FRP ropes are applied as external stirrups in the form of diagonal X-shaped reinforcement for the increase in the capacity of the part of the column connected with the beam (joint panel). Both specimens are tested under the same cyclic loading procedure that comprises seven steps and each step includes three full loading cycles. The maximum loads of the strengthened specimen at the three loading cycles of the seventh step were 40%, 72% and 87% higher than the corresponding ones of the unstrengthened specimen. On the other hand, the measured shear deformations of the joint panel of the pilot (unstrengthened) specimen at the sixth and the seventh steps were 43% and 44% higher than the corresponding ones of the strengthened specimen. In general, it is concluded that the strengthened column exhibited improved hysteretic response and the whole behavior was apparently improved compared to the pilot specimen without strengthening in terms of maximum loads per loading step, dissipated energy, and shear deformations of the joint panel. In particular, it is stressed that the measured shear deformations of the joint panel and strain gauge measurements have substantiated that the column and the connection panel of the strengthened specimen remain almost intact, whereas damage and eventually failure have been located in the column and the joint panel of the pilot specimen. Additionally, it is emphasized that the C-FRP ropes can easily be applied in structures with complex configuration without any geometrical restraints.

The Influence of Open-Ground Floors on the Impact of RC Columns Due to Seismic Pounding from Adjacent Lower-Height Structures

The substantial influences of masonry infills used as partition walls on the seismic behavior of multistory reinforced concrete (RC) structures have long been recognized. Thereupon, in this study, considering open-ground floors due to a lack of infills (pilotis configuration), the structural pounding phenomenon between adjoining RC buildings with unequal story levels and unequal total heights is investigated. Emphasis is placed on the impact of the external columns of the higher structure, which suffer from the slabs of adjoining shorter buildings. The developing maximum shear forces of the columns due to the impact are discussed and compared with the available shear strength. Furthermore, it is stressed that the structures are partially in contact, as is the case in most real adjacent structures; therefore, the torsional vibrations brought about due to the pounding phenomenon are examined by performing 3D nonlinear dynamic analyses (asymmetric pounding). In this study, an eight-story RC frame structure that is considered to be fully infilled or has an open-ground floor interacts with shorter buildings with ns stories, where ns = 6, 3, and 1. Two natural seismic excitations are used, with each one applied twice—once in the positive direction and once in the negative direction—to investigate the influence of seismic directionality on the asymmetric pounding effect. Finally, from the results of this study, it is concluded that the open-ground story significantly increases the shear capacity demands of the columns that suffer the impact and the inelastic rotation demands of the structure, whereas these demands further increase as the stories of the adjoining shorter building increase.

A Novel Uni- and Biplanar External Fixator for Initial and Definitive Complex Foot Trauma.

Evidence concerning the complex foot trauma, especially its definitive management, is scarce. Soft tissue envelope sequalae are the primary parameters that delay or make internal fixation implausible. Stability conferred by external fixators makes them a reasonable initial treatment choice. Although AO or circular fixators can be applied around the foot, this can involve a learning curve and substantial costs, especially for the circular fixator. There is little evidence as to how well external fixators work as a definite method of fixation in patients where progression to internal fixation cannot be made. We prospectively evaluated 10 adult patients with severe and complex foot trauma who were consecutively treated at our clinic. Initial reduction and stabilization were performed with an external fixator that was initially conceived for distal radius fractures, applied during the initial procedure and mantained throughout the treatment. Fracture healing was obtained in all 10 cases, and both internal and external column length was restored. One of the patients developed chronic osteomyelitis. At the 1-year follow-up visit, these patients averaged 45.6 points in the physical and 44.8 points on the mental status sections of the 12-Item Short Form Health Survey (SF-12). The Foot Function Index findings for pain, disability, and daily activities limitations were 33.3, 39, and 41.5, respectively, which suggest moderate residual impairment. In this relatively small case series of complex foot trauma, we found that the use of simple external fixation as definitive treatment worked reasonably well. Level III, prospective cohort study.

Seismic Assessment of Self-Centering Rocking Braced Systems with Story Energy Dissipation

Self-centering rocking braced (SCRB) system provides enhanced seismic performance and reduced post-earthquake residual drift. However, the effect of higher modes is controversial, affecting shear demands and bending moments in the structure. This functional deficiency is addressed by developing SCRB frames equipped with buckling-restrained columns (BRCs) and buckling-restrained braces (BRBs), performing as exchangeable fuse frames. The system consists of external columns branching off from the main core and connected to it via butterfly-shaped fuses, and BRC and BRB are incorporated into the core at four different height levels to be compared with conventional SCRB as the baseline. Three sets of 12-, 16- and 20-story structures are numerically developed in OpenSees finite element framework with regard to geometrical and material nonlinearities, making a total of 12 SCRB prototypes. The suit of 22 ground motions used in FEMA P695 was scaled to DBE and MCE hazard levels and applied to the structures. Results indicate the capability of the new system in reducing the destructive effects of higher modes, especially in the case of a fuse frame located in the middle of the height. In addition, the core moment and shear force largely reduced, almost 60%, in higher positions of the fuse frame, while those configurations led to large residual drift at the restrained level. However, all structures met the DBE-level 2% drift target. Moreover, increasing structural height nearly reduced seismic demands and increased response reductions. Overall, the system demonstrated acceptable performance in terms of high capacity for energy absorption.

A Review Study on Belt Wall in Non-Regular Buildings in Various India Earthquake Zones

To reinforce a building's central walls and external columns and boost its stability against overturning, outriggers are robust horizontal frameworks like beams and frames. While cantilevers have been an attribute of buildings for more than fifty years, their performance has been enhanced by innovative design concepts. The structural system known as the foundation system is made up of horizontal cantilever portions that are fastened to the structure's external columns and interior core. The system's lateral stiffness and central moment arm are both enhanced by this link. By joining the core and the building supports, the stabilizer lowers the back moments inside the core and transfers moments from the core to the exterior supports. Steel, concrete, and composite materials are just a few of the elements that can be used to make stabilization systems. Usually the core is positioned on one side of the building and the stabilizers expand on the opposite side, or the stabilizers expand on one side of the central core. To stop lateral movement, the perimeter of the building is attached together and expanded by column-connecting walls. Wall-mounted stabilizers are more efficient than wall-free ones. The center wall cannot freely rotate on the external columns due to the stabilizing arm. The location of outriggers and tie rods, the quantity of outriggers, the form of the structure, the type of core (steel or concrete), and the height from floor to ceiling are just a few of the elements that might impact how well outriggers and straps function in the structure. Several studies were selected for this review study with the purpose of analyzing the impact of belt walls on irregular structures. Obtain a thorough analysis of the types of irregular buildings and how earthquakes affect these constructions. Earthquake zones are used in India to categorize the degree of seismic loading. Keywords: Belt Wall, earthquake zone, Irregularities of Building, Storey displacement, bending moment etc.

Structural assesment and numerical analysis of existing reinforced concrete frame structure

The subject of this study is the presentation of in-situ tests on the existing structure and structural analysis of the Faculty of Political Sciences building at the University of Zagreb which sustained damage in the series of earthquakes that hit Zagreb and Petrinja in 2020, as well as the structural strengthening efforts undertaken thereafter. The load-bearing structure of this mid-20th century building is a reinforced concrete frame system (column-beam). Filling between frames is masonry made of solid bricks. The floor structure is reinforced concrete ribbed slabs, characteristic of the construction period. Structure has a basement and six floors above ground. In-situ testing revealed that the compressive strength of concrete was at least 30.7 MPa, and tensile strength of steel reinforcement to that of B 240. It was determined that that the existing masonry walls did not have sufficient shear resistance due to the degradation of the bonding material. Numerical model was made considering the peak ground acceleration of ag/g = 0.249, and the importance factor of γI = 1.2. The analysis showed that the existing building complied with 19% ag/g of today’s applicable regulations for designing earthquake-resistant structures. The main strengthening included the installation of external steel trusses on both facades connected to the external column or facade frame, thus not affecting the existing floor plan. RC walls were added to side of main building volume in the transvers direction and to the staircase portion in both directions as additional bracing. Since the calculations assumed the behavior of the frame for the existing load-bearing structure of reinforced concrete beams and columns, the joints were additionally reinforced by wrapping them with CFRP fabric to enhance reinforcement, since these areas are very sensitive to seismic action.

ANALYSIS OF THE RATIONAL DESIGN OF A HIGH-RISE BUILDING USING A SYSTEM OF OUTRIGGERS AND A CORE UNDER SEISMIC AND WIND LOADS

The article highlights the analysis of the rational design of high-rise buildings, in particular the use of outrigger and core systems, in order to study their effectiveness under seismic and wind loads. 
 The most rigid design of the outrigger (diagram B), in which vertical ties are located at each step of the perimeter columns, leads to a decrease in the horizontal movement of the top of the building by 24% compared to the building without the use of surface stiffness. However, this option is difficult to implement in practice, because in some points of the structure, for example, in the corners of the stiffness core, there is a significant number of elements with rigid nodes. Of the implemented structures, the greatest gain in movements (21%) is demonstrated by variant D, where the ties are evenly located along the perimeter of the arrangement and ensure the same transfer of horizontal influences [6] to the external columns. This version of the arrangement of connections is structurally much simpler than scheme B, with a small (less than 3%) difference in indicators. 
 The location of corner connections between the corners of the rigid core and the corners of the perimeter arrangement leads to a reduction of horizontal [7] movement by 5% in the absence of vertical connections on the short side, compared to the scheme without corner connections. It is important to note that the angular vertical connections do not compensate for the lack of longitudinal connections (schemes I - displacement of 197 mm, Y - 207 mm and Z - 190 mm). Installing only corner connections reduces the horizontal movement of the top of the building by 12% (scheme K), which is the smallest value compared to other options. 
 The use of the outrigger structure significantly increases the rigidity of the building [8], which in turn allows to reduce the cost of construction due to the reduction of the thickness of the building core and the area of reinforcement. 
 The most justified location of the vertical connections of the outrigger is the one in which they are evenly located according to the building plan, that is, they have the same interval along the entire perimeter. It is not recommended to use schemes where vertical connections are established only on the long side of the building [9], and especially only on the short side.Therefore, the use of a rigid belt in the building contributes to the reduction of horizontal movements at the entire height, effectively minimizes fluctuations caused by the influence of wind load. The use of an outrigger structure significantly increases the rigidity of the building, which in turn allows to reduce the cost of construction due to the reduction of the thickness of the building core and the area of reinforcement. 
 The most justified location of the vertical connections of the outrigger is the one in which they are evenly located according to the building plan, that is, they have the same interval along the entire perimeter. It is not recommended to use schemes where vertical connections are installed only on the long side of the building, and especially only on the short side.

Cervical Column and Cord and Column Responses in Whiplash With Stenosis: A Finite Element Modeling Study.

Spine degeneration is a normal aging process. It may lead to stenotic spines that may have implications for pain and quality of life. The diagnosis is based on clinical symptomatology and imaging. Magnetic resonance images often reveal the nature and degree of stenosis of the spine. Stenosis is concerning to clinicians and patients because of the decreased space in the spinal canal and potential for elevated risk of cord and/or osteoligamentous spinal column injuries. Numerous finite element models of the cervical spine have been developed to study the biomechanics of the osteoligamentous column such as range of motion and vertebral stress; however, spinal cord modeling is often ignored. The objective of this study was to determine the external column and internal cord and disc responses of stenotic spines using finite element modeling. A validated model of the subaxial spinal column was used. The osteoligamentous column was modified to include the spinal cord. Mild, moderate, and severe degrees of stenosis commonly identified in civilian populations were simulated at C5-C6. The column-cord model was subjected to postero-anterior acceleration at T1. The range of motion, disc pressure, and cord stress-strain were obtained at the index and superior and inferior adjacent levels of the stenosis. The external metric representing the segmental motion was insensitive while the intrinsic disc and cord variables were more sensitive, and the index level was more affected by stenosis. These findings may influence surgical planning and patient education in personalized medicine.

A seismic behavior of RCC high rise structure with and without outrigger and belt truss system for different earthquake zones and type of soil

In the present era, there is more demand for high-rise buildings. The growing de- mand for high-rise buildings brings new difficulties and comes up with new safety precautions. With an increase in height of the structure, its rigidity reduces, making it difficult to withstand earthquake and wind effects, hence some preventative structural systems must be used. Some of them are bracings, shear walls, outrig- ger systems and belt truss systems etc. The outrigger and belt truss system is investigated in this study since it is the most effective method for high-rise buildings and skyscrapers. To prevent story drift and the rotational action of the core caused by seismic and wind forces, the external columns in an outrigger system are attached to the main inner or outer core using outrigger beams, walls, and trusses etc. at various floor levels. All external columns that are situated at the peripheral are connected together with truss elements in a belt truss system. This study investigates the comparison of the behavior of high-rise buildings with and without an outrigger system, and belt truss system for all seismic zones (zone II, III, IV and V) with different types of soil (hard, medium, soft). This study is carried out for 40 story buildings using response spectrum analysis. Analysis of the building is carried out by using ETABS 2018 software. The results are in the form of seismic responses like storey displacement, Storey drift, base shear are studied. Results show that the provision of an outrigger and belt truss system reduces the story displacement of the structure. After analysis and comparing the seismic responses of the structure, the building provided with the combination of outrigger and belt truss system perform better as compared to the only outrigger and belt truss system.

Performance of Concrete Building Structure Exposed to Localized Fire

Concrete structures have a favorable position in the building industry with regard to their performance of fire resistance. The understanding of their behavior is essential for reliable analysis and design. This paper is mainly concerned with concrete building performance subjected to localized fire arrangement. Special attention has been given to the finite element model of a seven-story concrete building representing a typical commercial office building designed to European Standard. Very large displacements happened on horizontal direction of the floor slabs due to thermal expansions. The large displacement induced lateral movement of the floor slabs and created additional moments to external columns. Design engineers should ensure that the external columns have ability to accommodate lateral displacements during fire. Although, the thin external columns of the model can withstand these movements due to beneficial effect of membrane action developed to the floor slabs. Present analysis indicates that the performance of the whole structure is substantially different from the single isolated structural member behavior during fire. Although the current design procedures are conservative, design engineers have to consider the detrimental and beneficial effects of lateral slabs' thermal expansion in complete structure.

Fractura de estrés sucesiva bilateral del 5th metatarsiano, en niño con metatarso aducto.

Stress fractures of the lateral column of the foot are rare and almost always in the context of competitive sports. Stress fractures in children are even less frequent and are most often seen in cases of associated foot deformities, especially pes cavus varus or metatarsal adductus. We present the case of an 11-year-old boy with stress fractures of the fifth metatarsal of both feet with bilateral metatarsus adductus deformity. We recall the relative frequency of residual metatarsus adductus deformity in the older child, the greatly increased risk of stress fractures of the external column of the foot associated with this deformity, as well as refractures and nounion. Finally, to recall the signs and symptoms of metatarsus adductus deformity, as well as the radiographic aspects related to this fracture considering its rarity in children.

Analytical Study on Lateral Strength of Multi-Span RC Frame with Masonry Infill

Abstract A simple and accurate analytical model for defining the lateral strength of the multi-span RC frame with masonry infill has been developed in this study. This model is developed due to the limitation of the current analytical model which only can be applied to the single-span RC frame. Meanwhile, the structure in the building also is in a multi-span frame and masonry infill greatly impacts the portal structure. In the existing building, this analytical method is needed to calculate the lateral strength of the RC frame. Besides, the analytical method was developed based on the lateral strength analysis method of a single-span RC frame in which the modeling of a multi-span RC frame with masonry infill along with uniform span spacing was applied. Furthermore, an equivalent diagonal strut with the same thickness and material as the masonry panels was used instead of masonry infill in the frame structure. The external column has diagonal compressive forces on the top or bottom of the column. On the other hand, diagonal compressive forces work at the top and the bottom of the column in the internal column. The lateral strength of the infill was determined based on the frame infill contact length. Furthermore, in order to obtain the lateral strength of the structure, the experimental study of a multi-span RC frame with masonry infill under cyclic load was also tested. Applying the analytical model has shown promising results even after being compared with the results of the experimental work.

Numerical study on effect of constant and variable axial loads on RC column subjected to blast load

Explosion is an instant release of potential energy, heat, temperature and sound producing a pressure wave that travels away from the source radially on which the resulting force the blast wave is a blast load. Besides this, column especially external column as a main load bearing compressive structural component in buildings is the most critical structural element vulnerable to explosion and require an in-depth investigation on its performance against blast loads. Despite this, currently there is perceived gap and meagre of researches regarding numerical investigation on effect of presence of constant and variable axial loads on reinforced concrete column when subjected to blast load. In this study, the responses of reinforced concrete column under different scaled distance blast load scenarios accompanied by constant and axial loads were investigated. The finite element method of structural analysis was employed accompanied by nonlinear explicit time integration software LS-DYNA. The numerical analysis result revealed that RC columns subjected to large axial loads accompanied by small scaled distance blast scenario made the reinforced concrete column to suffer severe damages including crushing of concrete especially direct shear failures and breaking of reinforcing steel bars. In addition to this, comparing the nature and behaviour of variable axial loads with constant axial loads, the former loading case revealed larger nodal displacement values along height of column, and a higher displacement-time history curve was traced. On the other hand, the damage propagation nature of RC columns loaded with variable axial load was slow and progressive and different with RC columns with constant axial loads accompanied by small scaled blast scenario which was rendered to have a severely crushed concrete element without bending actions leaving the entire column inadequate for service.

Review on High Rise Building with Outrigger and Belt Truss System

Abstract: In present era there is more demand of high rise building. The growing demand for high-rise buildings brings new difficulties and comes up with new safety precautions. With increase in height of structure its rigidity reduces, making it difficult to withstand with earthquake and wind effects, hence some preventative structural systems must be used. Some of them are bracings, shear wall, outrigger system and belt truss system etc. The outrigger and belt truss system is investigated in this study since it has been found to be the most effective method for high rise buildings and skyscrapers. To prevent story drift and the rotational action of the core caused by seismic and wind forces, the external columns in an outrigger system are attached to the main inner or outer core using outrigger beams, walls, trusses etc. at various floor levels. All external columns that are situated at the peripheral are connected together with truss elements in a belt truss system. A number of studies on this subject that have been done in the past are reviewed in this paper. Reviewing research papers let us know about the conclusive results, which served as the basis for the objective of our future study. One of the best systems for controlling excessive drift and lateral displacement caused by lateral loads is the outrigger and belt truss system. By using this system, the risk of structural and non-structural damage can be reduced during small or medium lateral loads caused by either wind or earthquake load

Electrochemical Mechanical Properties of Beam-Column Joints of Building Steel Structures under Impact Loads

To optimize the seismic performance in high-rise buildings, the performance changes of beam-column joints of high-rise steel structures of buildings when they are impacted are analyzed to obtain the optimal choice of joint combination. The most commonly used steel beam and steel column joints are selected as the research objects. Firstly, the finite element model and the shell element model of the force are established and then the model of the finite element combination of six kinds of steel beam and steel column joints is established. Secondly, the applied data of common impact force in actual buildings are collected, and the simulated impact force in this experiment is established according to the sampled data. Then, the changes in each performance of the joints under the action of the impact external force are deeply explored through simulation. Finally, the accuracy of the model is confirmed by calculation. The experimental results comprehensively show that the transmission mechanisms of the impact force are different for the six joints. Through calculation and comparison, the bending stiffness, strength, deformation, the displacement degree of the joints, and the bearing degree of the impact external force are comprehensively analyzed. It is concluded that the bolt-type and external diaphragm-type steel tube column concrete and steel-beam concrete composite joints have better seismic resistance than the other five joints. The bolt-type does not need to be welded on site, and the on-site construction workers only need to assemble, which can reduce the technical requirements for construction workers, improving the practicability and applicability. Therefore, it shows reliable reference significance for the joint selection of building steel structures.

Distributed fibre optic sensing: Reinforcement yielding strains and crack detection in concrete slab during column failure simulation

Flat slab systems made of reinforced concrete (RC) are popular structural solutions widely used in practical applications. The knowledge about their behaviour under extreme loading conditions, including the loss of the columns, is still being developed worldwide. Also, new materials are tested for this purpose. The research presented hereafter in the article includes the progressive collapse simulation caused by removing the external column in the flat slab system reinforced with B600B steel. One of the aims of the research was to assess the effectiveness of the applied reinforcement after losing the column, depending on the degree of horizontal tie reinforcement. The structural behaviour of the entire reinforced concrete system during the experiment was controlled using advanced reference techniques, including distributed fibre optic sensing DFOS, optical image correlation system, total station as well as conventional strain and displacement transducers. The article focuses on the possibilities of DFOS sensing in an extensive range of strains caused by the steel yielding and the cracks directly in concrete. Thanks to distributed measurements and monolithic composite sensors, it was possible to detect all the cracks and reflect their patterns during all load stages until structural failure. The article describes the methodology and discusses the results of this pioneer measurement approach. Despite the extensive state of the art in distributed sensing, the paper provides the new knowledge gained during research. It is mainly related to a DFOS-based solution for extremely high strain measurements thanks to the excellent bonding properties and strain transfer to the optical fibre, from both steel reinforcement and surrounding concrete.

Comparative analysis of Wall Belt Systems, Shear Core Outrigger Systems and Truss Belt Systems on Residential Apartment

Abstract: The outrigger structural system is one of the horizontal load resisting systems. In this system the belt truss ties all the external columns on the periphery of the structure and the outriggers connect these belt trusses to the central core of the structure thus restraining the exterior columns from rotation. The shear wall was implemented to oppose lateral loads. To complete these characteristic the Outrigger & wall belt system used in the structure. In this project a G+10 Storey structure has analysed using seven different cases named as RA1 to RA7-OTB. 1 to 7 indicates single outrigger system, shear core outrigger system truss belt support system with optimized trusses, at various locations under seismic zone III. The built up area used for various case as 315 sq. m. After performing result analysis, the comparative analysis of all the cases shows that the most efficient case for the above study is Case RA4. Here for efficiency of the project, two types of optimized truss belt support which has performed well and observed as most optimized and correspondingly minimum in all the cases. Keywords: Truss wall belt support, core wall belt support, outrigger, wall belt, CSI-ETABS, multi-storey

Performance Assessment of an Energy–Based Approximation Method for the Dynamic Capacity of RC Frames Subjected to Sudden Column Removal Scenarios

The alternative load path method is widely used to assess the progressive collapse performance of reinforced concrete structures. As an alternative to an accurate non–linear dynamic analysis, an energy–based method (EBM) can also be adopted to approximately calculate the dynamic load–bearing capacity curve or the dynamic resistance based on a static capacity curve. However, dynamic effects cannot be explicitly taken into account in the EBM. The model uncertainty associated with the use of the EBM for evaluating the dynamic ultimate capacity of structural frames has not yet been quantified. Knowledge of this model uncertainty is however necessary when applying EBM as part of reliability calculations, for example, in relation to structural robustness quantification. Hence, this article focuses on the evaluation of the performance of the EBM and the quantification of its model uncertainty in the context of reliability–based assessments of progressive or disproportionate collapse. The influences of damping effects and different column removal scenarios are investigated. As a result, it is found that damping effects have a limited influence on the performance of the EBM. In the case of an external column removal scenario, the performance of the EBM is lower as the response is not a single deformation mode according to the results in the frequency domain. However, a good performance is found in the case of an internal column removal scenario in which the assumption of a single deformation mode is found to be sufficiently adequate. Probabilistic models for the model uncertainties related to the use of the EBM compared to direct dynamic analyses are proposed in relation to both the resistances and the associated displacements. Overall, the EBM shows to be an adequate approximation, resulting in a small bias and small standard deviation for its associated model uncertainty.

Experimental and numerical study on planar multi-column walls behaviours with boundary supports

The continuous-supported multi-column walls have already been used in modular steel buildings (MSB). Therefore, using two full-scale specimens, the current study evaluated the axial behaviour of planar multi-column walls with structural hollow sections (SHS). Then, a 3D finite element model (FEM) was created and validated to study the individual column and boundary support effects on each column. Prediction equations in EC3, AISC360, and GB50017 were then used to predict the ultimate compressive resistance of columns in walls. Because of the elastic buckling, the current slenderness limit for Class 3 steel cross-sections becomes less conservative. The boundary support effect enhances external columns rigidity and capacity than other columns, leading to instability. FEM provides reasonable estimates of the compressive behaviour of walls and each column. Each column exhibits distinct load distribution, confirming that the assumption of uniform load distribution among columns is unacceptable for multi-column modular walls. The prediction equations showed that GB50017 was safer than the EC3 and AISC, while EC3 was the least secure. Hence, the current study concluded experimental, numerical, and analytical findings to evaluate the axial behaviour of multi-column walls in multi-storey MSBs.

Seismic Behaviour of Steel Staggered Truss in Building

In this study staggered-truss system (STS) is studied for structural steel framing for the multi-story and high-rise buildings. The staggered-truss systems (STS) consists of a series of story-high trusses spanning the total width between two rows of external columns and arranged in a staggered pattern on adjacent column lines. The system is known to be appropriate for use in residential buildings such as apartments, dormitory and hotels. The columns are located only on the external faces of the building. The large clear span and open areas can be created. The interaction of the floors, trusses, and columns makes the structure perform as a single unit, there by taking maximum advantage of the strength and rigidity of all the components simultaneously. Each component performs its particular function, totally dependent upon the others for its performance. These column free areas can be utilized for ballrooms, concourses and other large areas. The one added benefit of the staggered-truss framing system is that it is highly efficient for resistance to the lateral loading caused by wind and earthquake. The stiffness of the STS provides the desired drift control for wind and earthquake loadings. The staggered-truss framing system is one of the quickest available methods to use during winter construction. The floor system not only carries the direct vertical loads. In addition, It has to act as a diaphragm to transfer the horizontal shear forces between stories through truss diagonals. Because of this double use concept this system results in a lighter structure and provides more column-free space than a conventional beam-column framed structure.