Bay Frame Research Articles

Seismic Analysis of Irregular Multistorey Building

Abstract: The seismic analysis of buildings is crucial for ensuring structural safety and resilience against earthquake forces. Irregularities in building configurations pose unique challenges, influencing the distribution of seismic forces throughout the structure. This study focuses on the seismic analysis of a G+12 building characterized by irregularities in plan and elevation using STAAD.Pro software. Here we have taken four models consisting of bare bay frame , bay frame with shear wall on one corner, , bay frame with shear wall on two opposite corners, , bay frame with shear wall on all corners for the further analysis. This research contributes to enhancing understanding and design practices for irregular high-rise buildings, emphasizing the importance of advanced analytical tools in seismic engineering. From this analysis we can conclude that within all four models ,building having shear wall on all four sides shows minimal deflection attributed to its maximum stiffness characteristics, hence considered most stable

Experimental investigation of steel frames made of hybrid steel welded I‐sections

AbstractAn experimental investigation into the structural behaviour of steel frames made up of hybrid steel welded I‐section members is presented in this paper. The tested hybrid steel welded I‐section profile had quenched and tempered S690 steel flanges and an S355 steel web. The experimental programme comprised four two‐dimensional, single storey, single bay frames subjected to different combinations of horizontal and vertical loading, thus enabling different beam, sway as well as combined beam and sway plastic collapse mechanisms to be examined. The frames were fully laterally restrained using a bespoke lateral bracing system to ensure that no out‐of‐plane instability phenomena were experienced during testing. The experimental setup, loading schemes, instrumentation and key experimental results are reported. The experimental results are fundamental to developing an understanding of the behaviour of hybrid steel welded I‐sections at the structural system level. Further research is underway to underpin the development of suitable design rules for steel frames made of such hybrid steel welded I‐section members.

Role of Importance Factor on Reinforcing Steel

Abstract: Aim is to study the change in reinforcing steel (percentage change) once we change the Importance Factor during the seismic analysis of a building. Importance factor classifies various structures on the basis of value 1 or 1.5 or even more depending on the structure importance. This value is provided in the seismic analysis of a building using STAAD PRO V8i version. The current code gives the Importance Factor value as “1” in case of “general buildings” and “1.5” in case of public or we can say important buildings. It also makes important buildings as heavier sections by increasing design base shear. There is no proof that how this importance factor works or improves the seismic factors of a building. In this study, the aim is to make a simple Bay frame using STAAD PRO for the purpose of analysis under seismic conditions and varying this respective importance factor and noticing the percentage change in steel reinforcement and the type of bars that are being used.

Research on Moulding Technology of Composite Payload Bay Frame

This paper describes a large-size grid closed cavity composite payload bay frame moulding technology, focusing on the process research of the moulding process scheme, mould design scheme and layering curing mode. The research shows that: the moulding of large-size grid closed cavity composite frame can be realized by layering the layer of each unit separately and integral co-curing. Through the process research, the key technology of integral autoclave curing and individual silicon rubber pressurization has been broken through to meet the requirements of even and stable pressure at all positions in the of moulding process of composite products. The residual internal stress can be effectively removed after several cycles’ temperature variation, and then the dimensional accuracy of the frame tends to be stable in a specific temperature range. The vertical bar position deviates from 0.3mm-0.8mm, and the deviation of the frame’s thickness is ±2%. The overall flatness of the plane where the installation interfaces of all key equipment are located is better than 0.2mm. The testing shows that the mechanical properties of the specimen are better than the design index, meeting the user's requirements

Effect of Material Used for Infill Wall and Its Shape on the Seismic Performance of RC Frame

Abstract: RC frame structure is one of common used building structures. Previous studies show that infill wall significantly contribute to the seismic performance imposed on RC frame structure, increasing structural stiffness and hence leading to decrease structure's natural period. However under strong earthquake, infill wall not only holds up large lateral seismic force but also limits the deformation of beams and columns. In most of the previous studies on the behaviour of reinforce concrete building considering the effect of infill wall, rectangular shape of brick is taken into account. In this study, an attempt has been made to look over the effect of infill wall material type and its shape on the seismic performance of RC frame. This study will be restricted with single bay frame with two types of bricks a) Clay brick, b) Fly ash brick. The different shapes under consideration are rectangle and square. This study also contains the effect of size of infill wall units. The stress in concrete, lateral force resisting capacity and displacement results have been obtained by finite element analysis and compared for all the cases. Keywords: RC frame, Infill, Micro modelling, FEA, ABAQUS

Comparison of Various Codes of Fire on Structural Design

Abstract: Fire situation is the significant issue in India and that of different designs is severely impacted by them. A portion of the design might fall after the fire in view of temperature impact. In this research, the primary spotlight on the beam and column of the structure. The standard fire curve is presented in IS code for a substantial steel support however for concrete neither fire curve is created nor any issue proclamation is given with the goal that various codes are utilized for the issue explanation. In this venture IS code, Euro Code, National Building codes of Canada and National code of Construction series of Australia are utilized. In reference of this codes the model to be framed in SAP programming with various information. The temperature for investigation is taken same for the whole model. The failed structures are over and over examined and make the model safe. Then the segment cross-segment and shaft cross-segment are taken and post process for the warm examination in SAFIR Software. This product is an issue sort of GID Software. In this the model are broke down by warm impact and post process in DIAMOND Software for the outcome. The similar examination of the Single bay frame model and 3-bay frame model for various codes is shown with assistance of chart. The correlation is in the middle of between standard fire curve and various codes. Keywords: Fire, SAFIR, DIAMOND, SAP-2000, Various Codes.

Strain investigation of infill frames using FEA package MSC NASTRAN

Masonry infill is usually neglected in the design and it is treated as a non-structural element instead of its stiffness and lateral resistance capacity. Their presence in the RC frame could also affect the lateral load resistance. The interaction of infill presence in the RC frame will also depend on the aspect ratio of frame and openings presence in the infill. The infill collapse initiated disaster of RC Framed structures are mainly concerned by the researchers recently. Many researchers considered experimentation up to a single-story single bay frame may be due to constraints in their facilities. A 3-bay 3-Storey Frame is considered in the present study using finite element package using MSC NASTRAN for different frame such as bare frame, Infill frame with different openings provided in it, and meshing was done finally strains were taken at middle third distances on each member of the internal panel of the bare frame, Infill frame, Infill frame with window opening, Infill frame with door opening, Infill frame with window and door openings and a comparison was made with infill frame and presence of openings in the infilled frame.

Investigation of Strain in Infill Frames using Nastran Patran

Masonry infill is usually neglected in the design and it is treated as a non-structural element instead of its stiffness and lateral resistance capacity. Their presence in the RC frame could also affect the lateral load resistance. The interaction of infill presence in the RC frame will also depend on the aspect ratio of frame and openings presence in the infill. The infill collapse initiated disaster of RC Framed structures are mainly concerned by the researchers recently. Many researchers considered experimentation up to a single-story single bay frame may be due to constraints in their facilities. A 3-bay 3-Storey Frame is considered in the present study using finite element package using MSC Nastran for different frame such as bare frame, Infill frame with different openings provided in it, and meshing was done finally strains were taken at middle third distances on each member of the internal panel of the bare frame, Infill frame, Infill frame with window opening, Infill frame with door opening, Infill frame with window and door openings and a comparison was made with infill frame and presence of openings in the infilled frame.

Optimizing the Design of Tall Buildings Using the Principle of Virtual Work: The Effect of Semi Rigid Connections

The Virtual Work Optimization Method (VWOM) is used to optimize tall buildings with semi rigid connections. The VWOM is an automated method that minimizes the mass of a structure with a given geometry, deflection criteria and load cases, while adhering to building code requirements. Members are selected from a user defined database to meet strength and stiffness criteria. The rotational stiffness of connections can be specified and varied, from rigid to pinned. The method is explained using an example of a two storey one bay steel frame with six members. Four case studies are presented: (i) a six storey two bay frame, (ii) a ten storey one bay steel building, (iii) a fifteen storey three bay steel frame and (iv) a twenty four storey three bay building. The examples are compared to results found in the literature. Structures were optimized for a range of connection rotational stiffnesses. The VWOM obtained results up to 44.6% lighter than published work. Optimized results showed that in most cases the semi rigid connection produced the same results as the rigid connections. This is due to the rapid plateauing of the optimized mass as the connection stiffness increases. Thus, the typical definition of semi rigid and rigid rotational stiffnesses (for example Eurocode 3) are both found on this plateau. If some members are lightly loaded, broad semi rigid and rigid bands can be produced. The effect in these cases is that structures with rigid connections are lighter than those with semi rigid connections as no compensation in the member stiffness is required to meet deflection criteria.

A simplified procedure for the seismic analysis of RC moment resisting setback frames

Irregularity in elevation of buildings is increasingly popular in modern urban construction. One of the prominent forms of vertically irregular frames is the setback building frames. The seismic performance of buildings with irregular distribution of mass, stiffness, and strength along the height may be significantly different from that of regular buildings. The present paper focuses on quantification of irregularity and studying the effect of irregularity on the seismic performance of setback building frames. An index namely Geometric Regularity Index (GRI), calculated based on the geometric parameter of the building frame, is proposed in the study to quantify the vertical irregularity of setback building frames. 55 numbers of 3 bay frames with stories 5, 7, 9, 11 and 13, with varying levels of irregularity, are considered in the study. Linear dynamic analysis of the frames is performed in ETABS using response spectrum method. The proposed index is correlated with the actual seismic response of the structure such as base shear and overturning moment. Based on the results of analysis, a simple method which employs the GRI of the frame is proposed to estimate the seismic responses such as base shear and overturning moment at the base. The proposed method is found to estimate the seismic response of setback frames with reasonable accuracy.

Influence of pneumatic interface pressure in reinforced concrete infilled frames

High rise buildings have now become order of the day in developed and developing countries. Allround population explosion, fast urbanization and rapid industrialization all try to take over the available land space, making it difficult to provide people their two basic needs viz food and shelter. Thus there is a pressing need to conserve and use judiciously the available land space. To meet this challenge are constructed, more and more of high-rise buildings which require relatively less ground space. In this study on prototype seven storeyed frame with an aim of studying the interactive effect of multiple floors being subjected to pneumatic pressure so as to find the possibility of controlling the entire infilled frame action through the control of any one floor and the practical aspects of replacing cement mortar interface with the proposed pneumatic interface. And also the Experimental investigation on one fourth scale model of seven storeyed single bay frames including developing of the test rig for lateral loading of the test specimen. The aim of this stage of studies is to practically verify the effect of introducing interface pressure on multi storeyed infilled frame.

Seismic behavior of masonry-infilled precast concrete frames considering effects of opening

Abstract It is commonly accepted that addition of infilled masonry walls (IMW) could enhance the in-plane strength and stiffness of RC frame buildings subjected to seismic loads. However, once the IMW walls failed, the shear force initially resisted by the IMW has to be transferred to the surrounding frames and may incur shear failure to the frames. Despite the extensive studies carried out in the past decades, studies on the structural performance of masonry infilled precast concrete (PC) frames are few. In this study, eight half-scaled single-story one bay frame were tested subjected to seismic loading, including three reinforced concrete (RC) frames and five PC frames. The investigated PC frames deviates the beam potential plastic hinge zone away from beam-to-beam connection region. The variables investigated in the tests included the types of opening in masonry infill walls and the types of cast-in-place concrete at the connections (normal concrete or steel fiber reinforced concrete). Results indicated that the investigated PC construction method has minimal effects on inelastic behavior and ductility of bare and infilled frames. However, the PC construction method may affect the crack development, especially at the interfaces in between precast and cast-in-place concrete surfaces in the region of the connection. However, the load resisting capacity and ductility was insensitive to the usage of steel fiber reinforced concrete at the connections, especially for bare frames.

Experimental and numerical assessment of EBF structures with shear links

Eccentrically braced frames (EBF) represent an optimal structural solution for seismic prone areas, being able to provide high dissipative capacity and good elastic stiffness, to withstand strong seismic events without significant loss of bearing capacity and to avoid damage to non-structural elements in case of low and moderate earthquakes. The accurate knowledge of the cyclic behaviour of the dissipative links, characterizing the whole performance of EBFs, is required to optimize the structural properties and to refine the design techniques adopted for multi-storey buildings' analysis. Reliable numerical models for the links, at the same time requiring a limited computational effort, are then needed. The present work shows the results of a wide experimental test campaign executed on real-scale one storey/one bay frames with horizontal and vertical links, together with the elaboration of a simple semi-analytical model for the quick representation of the cyclic behaviour of shear links.

TADAS dampers in very large deformations

Triangular-plate Added Damping and Stiffness (TADAS) dampers are special kinds of passive control devices that can be used in seismic design and retrofitting of structural systems. However, when exposed to large deformations, primary members of a structure can be in danger of serious damage due to improper geometric characteristics of these dampers. In this study, response of a one bay frame equipped with a TADAS device, previously tested in the laboratory, was simulated using a detailed FE model in ABAQUS. A monotonic analysis was then conducted on the TADAS damper alone, which indicated that in large deformations, TADAS damper pins hit the top of the holes, resulting in an abrupt stiffness increase in the damper. Seismic analysis of a six story moment resisting frame with TADAS dampers, using a series of twelve scaled earthquake ground motions, was also conducted in OpenSees which indicated that with sudden stiffness increase in dampers, the value of moments in beams as well as axial forces in braces will increase, causing possible damages in these areas. At the end, a method for calculating the optimal height for the holes in the damper was proposed, which is shown to be in good agreement with detailed ABAQUS models.

Effect of post tensioning on strengthening different types of steel frames

The aim of this paper is to study the effect of post tensioned cables on strengthening steel frames and improving their load carrying capacity, giving more resistance against the external load (dead plus live or wind load). Different types of frames are analyzed: simple frame, double bay frame and double story frame. The analysis and the results are obtained using ANSYS finite element (FE) program. Different techniques were used to apply post tensioning to steel frame. Comparisons are made between these techniques to determine which technique is better in strengthening each type of frame. The results show that using post tensioned cables increases significantly the load capacity of the steel frame.

Lateral performance of a Pres-Lam frame designed for gravity loads

This paper analyses the lateral load performance of a post-tensioned timber (Pres-Lam) frame which was designed with the primary function of supporting gravity loading. A full scale, two bay frame was used and subjected to quasi-static horizontal displacement. A total of four tests were performed, one with only the post-tensioning cables to resist horizontal loading and three with the addition of sacrificial steel elements externally attached and acting as dissipative reinforcing. This external reinforcing increased the moment capacity of the frame connections and the ability of the frame to release energy through hysteretic damping. Following a description of the test setup the results show that although the primary functions of the post-tensioning is to reduce section height and increase bay length under gravity loading it will also provide a significant contribution to the lateral resistance of the structure. Finally, a simplified design procedure is presented which allows assessing the magnitude of this contribution.

Numerical simulation of RC infill walls under cyclic loading and calibration with widely used hysteretic models and experiments

Addition of reinforced concrete (RC) infill walls into the structural system has been a commonly preferred strengthening technique within the last decades for seismic rehabilitation of RC frames. As a consequence, generating a representative numerical model of an RC infill wall has become an important issue. As the initial step of this study, measured structural responses of two selected well-known large-scale RC infill wall experiments subjected to displacement controlled cyclic loading are taken into account. Later, by calibrating the numerical model prepared in Perform-3D computer program utilizing fiber cross-sections, a practical and a compatible analytical model is obtained and proposed herein. Structural systems of the experiments are mathematically modeled by elements consisting of vertical and horizontal fiber layers to represent the bending/axial behavior and to control the out of plane displacements, respectively. Nonlinear behavior of the reinforcing steel is represented by a tri-linear backbone curve without strength degradation, while a multi-linear hysteretic behavior considering the strength loss is utilized for the structural concrete. Furthermore, those recently conducted experiments are simulated by a couple of widely used hysteretic models for comparative purposes, which are preferred in most cases by the researchers during the analytical investigation of RC structures, so that their adequacy for reflecting the nonlinear behavior of infill walls are also studied. It is shown with comparisons for the experimentally measured and the analytically derived results that the calibrated mathematical model proposed herein is more compatible with the measured values than the widely used hysteretic rules for capturing the behavior of these types of frames retrofitted by RC infill walls under reversed cyclic loading. Although numerical simulations are carried out for a limited number of tests and it is assumed that sufficient amount of anchoring dowels is provided at the interface of the existing frame and the RC infill, the proposed calibrated model conforms to both experiments’ measured responses by means of seismic behavior for not only the undamaged single bay frames converted to the RC infill wall, but also pre-damaged multi-bay strengthened structures, which include structural deficiencies like low concrete strength, inadequate stiffness and insufficient confinement.

Potential Use of Locked Brick Infill Walls to Decrease Soft-Story Formation in Frame Buildings

AbstractThe objective of this study is to investigate the effects of a new type of infill—called locked brick infill adopting horizontal sliding joints—in reducing the soft-story formation in reinforced concrete (RC) frames with code-conforming seismic detailing. Nonlinear static time-history analyses were performed on multistory planar frames with only the upper stories infilled in order to force the soft-story irregularity. The parameters of frame and infill elements that were used in numerical simulations were obtained from half-scale RC infilled frame tests that had been performed by the author covering single story–single bay frames infilled with standard and locked bricks. The numerical simulations showed that the use of locked bricks to form infill walls has the potential to decrease the soft-story/weak-story formation in comparison to standard bricks due to its shear sliding mechanism and decreased upper-story/first-story stiffness, even in buildings that have noninfilled first stories.

Free vibration analysis of beams and frames with multiple cracks for damage detection

The problem of calculating the natural frequencies of beams with multiple cracks and frames with cracked beams is studied. The natural frequencies are obtained using a new method in which a rotational spring model is used to represent the cracks. For beams, dynamic stiffness matrices of order 4 are obtained in a recursive manner, according to the number of cracks, by applying partial Gaussian elimination. The Wittrick–Williams algorithm is used to compute the natural frequencies in the resulting transcendental eigenvalue problem. Published numerical examples for cracked beams are used for validation. The global dynamic stiffness matrix of a frame with multiply cracked members is then assembled. A published two bay frame example is used to evaluate the new method. The effect of changing the location of a crack in a two bay two storey frame is studied numerically, giving insight into the inverse problem of damage detection.

Reliability-based analysis and design of steel frames with different supports

Purpose – The behaviours of four indeterminate frame-support combinations namely Type I (with fixed supports), Type II (with pinned supports), Type III (with fixed-pinned supports) and Type IV (with fixed-roller supports) frames under the exposure conditions and loads as existing on site were simulated. Two categories of these combinations (I and II) were studied namely single storey-single bay and multiple storey-single bay frames, as illustrated in the case studies treated. A procedure for determining the probability of failure at different sections along the frame types, the range between the probability of failure bounds and the reliability ratings of the frame types were developed based on the kinetic method of plastic moment analysis, minimum weight design method, piecewise method of moment analysis and first order-second moment (FOSM) methods. The analysis results of the Category I frames showed that the Type I frame was most reliable (with the lowest probability of failure range of 0.3269), while the Type II frame was least reliable (with the highest probability of failure range of 0.4918). These results were consistent with those of the Category II frames. The paper aims to discuss these issues. Design/methodology/approach – Collapse mechanisms were generated for four frame-support types and the corresponding plastic moments were determined using both the kinematic plastic analyses and minimum weight design methods. The members were designed and the plastic moments were distributed at sections of constant interval along the frame length to generate corresponding envelopes. A similar process was carried out to determine the elastic moment variables due to the loads. The reliability index and the corresponding probability of failure at each frame section were determined. Then, the probabilities of failure bounds for the frames were then compared to determine the most reliable. Findings – It was observed that there existed a wide margin between the elastic and plastic moments indicating that design of steel structures at the elastic limit does not take full advantage of its strength. Hence, the design can be carried out beyond the elastic limit and within the safety margin given in equation (3). However, the safety of the entire frame is assessed on the basis of range of values between the highest and the lowest probability of failure bounds. The lower this range is (not exceeding 0.5 or 50 per cent), the more reliable the frame is. Research limitations/implications – The equations developed in this study can only be directly applied to multi storey-single bay frames. However, the reliability-based analysis and design procedure developed can be extended to other types of frames. Practical implications – A practical approach for analysing steel frames with different supports with the overall goal of producing safe and economical designs has been developed and presented in this paper. Originality/value – The procedure adopted is very original and can be backed up by existing literature. The piecewise method for analysing moments at various sections along a frame is also innovative. The whole concept can be adopted to determine the reliability of other types of frames such as multiple bay-multistorey frames with different support types.