Multi-storey Frame Research Articles

Infuence of inverted-v-braced system on the stability and strength of multi-story steel frames

Population growth in urban centers, together with the lack of physical space, has led to the construction of increasingly tall and slender buildings. Multiple-story structures present substantial challenges to civil engineering because they have specific requirements for their design, construction, and use. The increased number of foors leads to more lateral displacements resulting from horizontal actions. Under these conditions, to ensure system stability, structural bracing components are commonly adopted. In addition, along with the use of more resistant materials and new construction techniques, it is necessary to improve the methodologies adopted in the structural analysis to offer professionals in the area the conditions to undertake safer and more economical projects with better speed and efficiency. Thus, in this study, numerical analyses were applied to steel planar reticulated structures to evaluate their stability and strength when inserting bracing systems. The study compared the arrangement of the bars and analyzed the influence of the parameters of the bracing systems, such as the properties of the cross-section and the position of the inverted-V-braced system. The MASTAN2 program was used to perform nonlinear static assessments using reticulated finite elements that considered both geometrical and physical nonlinearities. It was observed that the inverted-V-braced system had a substantial impact on all of the structures that were analyzed, providing increased stiffiness and, as a result, significantly reducing the frame’s lateral displacement.

Pseudodynamic Tests and Numerical Modelling for Damage Analysis of Infilled RC Frames

ABSTRACT Full-scale experimental tests are still needed to enhance knowledge on the seismic response of existing reinforced concrete buildings and to calibrate numerical models aimed at predicting damage. This study deals with pseudo-dynamic (PSD) tests and numerical modeling of full-scale multi-story infilled RC frames with different infill-to-frame connections. Nonlinear numerical models are calibrated using the experimental results at frame level and validated against the results of time-histories in terms of displacement demand, hysteretic response, and attained damage. This model is extended at building level and used to predicted damage to infills. The comparison with damage observed during post-earthquake inspections is reported and discussed.

Numerical Investigations of Progressive Collapse Behaviour of Multi-Storey Reinforced Concrete Frames

This paper presents numerical simulations of multi-storey reinforced concrete frames under progressive collapse scenarios. Reinforced concrete frames with different storeys are modelled using DIANA. The load resistance and failure mode of frames are obtained from the numerical simulation. Variations in axial force and bending moment at the beam end are also determined and analysed to shed light on the force transfer mechanism. Numerical results show that the single-storey frame can develop compressive arch action at the initial loading stage and subsequent catenary action at large deformations. However, in multi-storey frames, only the first-storey beam develops compressive arch action and catenary action, whereas beams in other storeys show rather limited axial compression force. Based on numerical results, a design method is proposed for multi-storey frames to resist progressive collapse. Comparisons between numerical results and design methods suggest that the design method can evaluate the progressive collapse resistance of multi-storey frames with good accuracy.

DETERMINATION OF DYNAMIC FORCES
 IN COMPLEXLY STRESSED ELEMENTS OF REINFORCED
 CONCRETE FRAMES UNDER SPECIAL IMPACT

On an energy basis, without involving the apparatus of dynamics of
 structures, an analytical solution of the problem was obtained to determine the dynamic
 additional loads in complexly stressed reinforced concrete elements of multi-storey frames
 in a transcendental state caused by special emergency effects. The stress state, crack
 patterns and fracture patterns in the crossbars of the considered frame structures are
 determined by the complex stress state of the frame elements caused by the combined action
 of torsional and bending moments. The assessment of the bearing capacity of such
 structures was carried out by the diagram method based on the use of energy ratios in the
 structural elements before and after a special impact, which makes it possible to determine
 the maximum dynamic deformations, curvatures and forces in the first half-wave of
 vibrations using the results of nonlinear static calculations according to the primary and
 secondary design schemes.

An improved Bayesian model updating framework by enhanced iterative model reduction technique in time domain

An improved Bayesian model updating technique in the Transitional Markov Chain Monte Carlo framework in time domain is investigated. In doing so, a modified iterative model reduction technique is embedded within the improved Bayesian framework to address the limited availability of measurements. The transformation relation proposed includes the inertial effect in each term of the dynamic condensation equation making it less dependant on the selection of master degrees of freedom. This expects to predict responses efficiently from the reduced-order model for stiffness reductions involved in structural health monitoring problems. The proposed algorithm modifies the transition levels of sampling by performing weighted sampling at all levels, a modified choice of plausibility value and adaptively estimating the sample and covariance matrix for the proposal distribution with a tuning algorithm. Thereby, the proposed approach reduces the dependency on the determination of the statistical estimators in obtaining the transitional samples. The efficiency of the algorithm is demonstrated considering simulated data of a multi-storied frame and an available experimental dataset of a multiple spring-mass system. A comparative study of the accuracy and computational efficacy of the proposed approach is made with the existing approaches.

Parametric Study on Built-Up Cold-Formed Steel Beams with Web Openings Connected by Spot Welding

This paper presents a numerical parametric study on cold-formed steel built-up beams subjected to bending. The cold-formed steel built-up elements are efficient structural elements that are easy to assemble during the construction process, ensuring material savings and potential for standardization, thus making them more suitable for mass production. A new technological solution for built-up steel beams with webs made of corrugated steel sheets and flanges made of cold-formed steel profiles, assembled through two welding techniques, was proposed within the well-formed research project. This solution can be used as a component of single or low-rise multi-story frames, purlins, or secondary beams. The experimental program investigated seven full-scale beams, two of which have web openings. The web openings were introduced for the case when these members are used as secondary beams in floor systems. The paper investigates these types of beams with web openings using parametric numerical analyses. A numerical model validated against experimental tests was proposed to carry out a parametric study through nonlinear finite element analysis, considering initial imperfections and considering the strain-hardening characteristics of the steel components. The influence of different components was analyzed through the parametric study. Beams with three lengths were studied, i.e., (1) 6000 mm, (2) 7500 mm, and (3) 9000 mm. In total, 61 simulations were found. The article highlights the parameters that contribute significantly to the stiffness and capacity of the built-up cold-formed steel elements. The weakest component was concluded to be the thickness of the corrugated web, while the presence of the stiffened web opening reduced the bearing capacity by approximately 5–10%.

Influence of soil-structure interaction modeling on the behavior of multi-story plane steel frames with shallow footing foundations

Traditionally, structural analysis is based on the hypothesis that supports are indeslocable due to simplicity. However, the conventional design in which settlements of foundation elements are disregarded can lead to physical results that are incompatible with reality. This work aims to analyze the influence of the consideration of soil-structure interaction (SSI) on the responses of steel structural elements obtained by a static second order analysis. Furthermore, it is evaluated the responses obtained by different types of procedures for the consideration of soil stiffness in the structural analysis. Solid elements considering linearly elastic material parameters and spring elements based on the Winkler theory are employed. The analyses were performed with the commercial software SAP2000. Plane steel frames models were analyzed, either considering conventional supports or taking into account the soil-structure interaction. Shallow footing foundations are considered. Three frames with the same characteristics, but with a different number of floors were analyzed, showing the influence of the height increase and the building stiffness on the SSI results. It has been shown that the consideration of the effects of soil-structure interaction on structural analysis of buildings can have a significant influence on the stress distribution, displacements and structural behavior. In addition, it is concluded that the structural capacity of steel frames can be affected by the type of support adopted and by changes on the way the model considers soil deformation.

Seismic performance of multi-storey steel frames with semi-rigid joints

In this paper, a numerical study on the response of multi-storey moment-resisting steel frames subjected to seismic actions, accounting for the real behavior of both the beam-to-column joints and the column bases, is presented. Two real benchmark buildings are considered for the purpose. The examined buildings are characterized by beam-to-column joints and column bases with semi-rigid and partial-strength behavior, although they were improperly assumed as rigid and full-strength in the original design process of the frames. In order to appraise how this wrong assumption influenced the building safety, finite element models are set up, first by modelling the joints according to the original design approach and then including the real stiffness and strength. Nonlinear dynamic analyses are performed and fragility curves for different limit states are obtained, considering the record-to-record variability as main source of uncertainty.

Proposal of a simple expression for predicting the horizontal capacity of masonry walls

In this paper, a simple expression for predicting the horizontal capacity of multistorey unreinforced masonry frames is proposed and discussed in the framework of limit analysis approach.To this aim, the panels of Convent of San Carlo all'Arena in Naples has been analyzed via nonlinear static analysis. The results have been compared with the values provided by the application of the proposed simple expressions, which only depend on geometrical parameters and external loads.The results show that the values obtained with the simplified formula are very close to the values obtained by pushover analysis, especially if higher compressive strength values are assumed, and the scatters assume greater values as the irregularity in the arrangement of the openings in the vertical and horizontal direction increases.

Comparative Analysis of Multistorey RCC and Semi-Rigid Steel Frame with Cross Bracings Subjected to Mainshock and Aftershock Earthquake Sequence

Strong Ground Motions have a significant impact on structural analysis and design. Seismic evaluation is deemed necessary for the quality, reliability, and feasibility of existing and developing structures. Earthquakes are even more disastrous when a mainshock is succeeded and preceded by aftershocks of higher magnitude. Most of the time, these aftershocks are ignored during analysis. In the last few decades, steel buildings have been crucial to the construction sector. On the other hand, RCC frames are commonly designed structures for commercial purposes and cost-effectiveness. IS 1893 (Part:1)-2002 Criteria for Earthquake Resistant Design of Structures and IS 13920-2016 Ductile Detailing of RC Structures Subjected to Seismic Reactions are majorly used for Seismic Analysis. Steel bracings in the structural system increase the ductility and stiffness of the frame structure. That can be arranged in a variety of ways, such as X, diagonally, alternatively, V, inverted V, K, etc. Cross bracings are used in this paper for the design of a typical multi-story (G+9) semi-rigid steel frame and a typical RCC frame is designed of the same dimensions. Both the frames are modelled and compared using ETABS software and a static nonlinear Time History analysis is executed to examine the performance of both the frames under the Mainshock and Aftershock of Chamoli earthquake. The Mainshock and Aftershock results of the Chamoli earthquake are extracted from the Centre for Engineering Strong Motion Research Ground Motion Database. Base shear, joint displacement, kinetic energy, and story displacement are a few of the variables of Time History Analysis that affect how well a building performs during mainshock and aftershock earthquakes. When analysing the outcomes, it is important to take into account that each of these factors significantly affects how a building responds to seismic loads.

既存壁式鉄筋コンクリート造建築物において下階壁面内に施工される接着系あと施工アンカーの引張特性に関する実験的研究

For the renovation of the reinforced concrete boxed-wall building, a new opening would be constructed on multi-story wall frame, and local retrofit with post-installed adhesive anchors would be applied. In this study, evaluation method of tensile strength for a post-installed adhesive anchor embedded in wall plane was proposed. The non-fixed bond-tensile test of anchor specimens embedded in wall-slab specimen was conducted. The parameter of specimens are embedment length of anchors, wall thickness, and wall shapes. Tensile strength of the anchors could be evaluated due to previous formula with the assumption of the effect of local retrofit on bottom floor wall and floor slab.

РАСЧЕТ ПАРАМЕТРОВ ДЕФОРМИРОВАНИЯ ЖЕЛЕЗОБЕТОННЫХ РАМ ПРИ РАЗРУШЕНИИ РИГЕЛЕЙ ПО НАКЛОННОМУ СЕЧЕНИЮ

On an energy basis, the problem of calculating the nonlinear deformation of structures of reinforced concrete multi-storey frames during the destruction of crossbars along an inclined section from special influences caused by structural restructuring of the structural system is solved. Analytical dependences are obtained for determining the parameters of the "moment-curvature" and "transverse force-shear" diagrams in the static-dynamic loading mode of the structures under consideration. The limiting load is determined at which, in the considered structural system of the ring, after applying a special effect in the form of a sudden removal of one of the columns, a special limiting state is achieved with the destruction of crossbars along inclined sections. The obtained design scheme of the destruction of the crossbars of the frame structures under consideration caused by the combined action of bending moments and transverse forces is compared with the destruction scheme obtained experimentally.

An innovative framework for risk assessment of non-structural components for industrial plants

Na-Tech events (Natural Hazard Triggering Technological Disasters) are industrial accidents triggered by natural events such as hurricanes, floods, earthquakes, tsunami, etc. In the recent decades, various analytical approaches for the performance-based earthquake engineering (PBEE) have been developed. The most famous approach has been provided by the Pacific Earthquake Engineering Research (PEER) Center, which consists of four stages: hazard analysis, demand analysis, damage analysis, and risk assessment. The accuracy of this method in the case of complex critical infrastructure, such as nuclear and non-nuclear industrial plants, is still under investigation. Specifically for these critical structures, it is necessary to define different Limit States and appropriate Engineering Demand Parameters (EDP), especially in presence of critical Non-Structural Components (NSC), whose damage can have serious consequences. Furthermore, because of the narrow distribution of frequencies in the demand of NSC, the selection of ground motion records for fragility analysis is also a critical aspect. Consequently, the aim of the proposed study is to investigate the suitability of the PBEE approach in presence of NSCs and their dynamic interaction with the primary structure. On these premises, a comprehensive shake table test campaign was carried out with the aim to investigate the seismic behaviour of two structural configurations of a representative industrial multi-storey frame equipped with process NSCs. The main limit states for NCSs are identified and the related fragility curves are built, in a PBEE perspective, based on both experimental results and finite element model (FEM) simulations. For this purpose, an innovative algorithm for ground accelerogram selection is used. Finally, the mean annual frequency (MAF) of exceedance of the experimentally identified limit states for relevant NSCs is carried out.

Account of compliance of precast disk of overlapping in the calculation of frames

The article provides a description of the methodology for taking into account pliable interfaces of prefabricated reinforced concrete disks of floors of multi-storey frame buildings when modeling by the finite element method. The results of numerical studies and a comparative analysis of numerical studies of the compliance of the floor disk with experimental data are presented. The results of the study of the effect of compliant interaction of structures on the stress-strain state of a multi-storey frame are shown.

Computer simulation of load-bearing elements and junction units in the calculation scheme of multistory frame buildings

In the last three decades, preference was given to the construction of monolithic buildings, but the construction of multistory frame buildings from prefabricated concrete is very relevant at the present stage. Therefore, there is a need to revise the normative base for the design of prefabricated housing construction, including the revision of standards for certain types of prefabricated reinforced concrete structures. Such work is currently being carried out taking into account the use of modern building materials, new technologies for the production of prefabricated structures and the erection of prefabricated buildings, as well as taking into account the widespread use of computer design methods in design practice. The Code of Rules for the design of multistory frame buildings in prefabricated concrete SP 356.1325800 was developed as an extension of the Code of Rules for the design of reinforced concrete structures SP 63.13330. The article reviews the normative and technical literature on the computer simulation of load-bearing elements and junction units of the calculation scheme of multistory frame buildings. The means of the LIRA software package for computer simulation are considered and a quantitative assessment of the stiffness of the connection in the hinged joint of the crossbar with the column, as well as a flat model for assessing the stress distribution in the cantilever of this joint, is proposed.

Fragility curves for reinforced concrete frames characterised by different regularity

This paper presents a comparison between fragility curves developed for regular and non-regular reinforced frames. Three 3D reinforced concrete multi-story frames characterised by different regularity are analysed. These fragility curves are developed through the “Cloud Analysis“ procedure, which evaluates the structural response via Non-Linear Time History Analysis (NLTHA).Both maximum inter-story drift and maximum chord-rotation demand/capacity ratio are used as Engineering Demand Parameters, in which the chord-rotation capacity is calculated according to the Italian Code. To fully develop the fragility curves, both structure-independent and structure-dependent scalar intensity measures are selected among the most referred in practice and literature.This work shows the influence of regularity on the damage levels of the three buildings. Furthermore, it shows the uncertainties caused by the selection criteria for EDP thresholds, which are necessary for a correct representation of the Limit State.

Comparison of seismic structure design in the world

Aseismic performance is one of the important technical indexes of modern buildings, which has been written into the building codes in various countries. Aseismic structure design is to enhance the stability of the building structure, ensure the safety of the building when the earthquake disaster occurs, reduce the loss and casualties. Since ancient times, innovations have been made in the design of seismic structures worldwide, especially in areas with high earthquake incidence. It was found in the previous research that the calculation method and design of seismic structures in American and Chinese building codes are different. Based on the interest of aseismic design, this paper summarizes the traditional and new aseismic structures. This paper first introduces several commonly used aseismic structures, such as multi-storey masonry, frame and seismic wall construction. Then this paper introduces the characteristics and differences of aseismic structure design in different countries from the modern and ancient time dimensions. In the end, Finally, it is concluded that the seismic structures are different due to the differences of geography, culture and climate in various countries. We can learn from the seismic structure analysis of ancient buildings that Aseismic structure design does not have to resist earthquake, but can reduce the damage of earthquake to the building by reducing the seismic force of the building.

Experimental evaluation of composite and non‐composite columns and braces in special concentrically braced frames

SummaryHollow structural section (HSS) and concrete‐filled tube (CFT) cross‐sections have been widely employed in the columns and braces of special concentrically braced frames (SCBFs). Square‐HSS cross‐section widely used in multistory frames is filled with concrete and converted to square‐CFT cross‐section to enhance the behavior of this cross‐section. However, some investigations indicated that circular‐HSS cross‐section filled with concrete (circular‐CFT) showed better behavior in comparison with square‐CFT cross‐section due to more uniform and larger concrete confinement in circular‐CFT cross‐section. The current study was experimentally undertaken to evaluate (1) the seismic performance and the global and local hysteresis responses of HSS and CFT members with various cross‐section shapes from initial elastic range to collapse in the system level of multistory SCBFs, (2) the behavioral differences between square cross‐section and circular cross‐section, and (3) the behavioral differences between HSS cross‐sections and CFT cross‐sections employed in the columns and braces of SCBFs. Four full‐scale one‐bay, two‐story SCBFs with four various cross‐sections, namely, square‐HSS, circular‐HSS, square‐CFT, and circular‐CFT, for columns and braces were subjected to cyclic lateral loading. Evaluating base shear–roof drift hysteretic loops of SCBF specimens demonstrated that SCBF specimens with CFT columns and braces (CFT‐SCBFs) experienced respectively around 107%, 58%, 28%, and 152% higher stiffness, post‐yielding and post‐buckling strengths, ductility, and energy dissipation capacity than SCBF specimens with HSS columns and braces (HSS‐SCBF). In addition, the experimental observations indicated that CFT braces experienced local buckling initiation, crack initiation, and fracture at respectively 2.22, 2.35, and 2.32 times of roof drifts of those exhibited by HSS braces. Moreover, assessing braces with various cross‐sections indicated that CFT braces showed an increase in compression strength, post‐buckling strength, compression axial deformation, and out‐of‐plane buckling approximately by 83%, 152%, 127%, and 100%, respectively, in comparison with HSS braces. Finally, square‐HSS/CFT braces sustained rupture propagation better than circular‐HSS/CFT braces.

Information Modeling of the Administrative Multi-Storey Building Frame Reconstruction

Introduction. The present study is targeting the problem of choosing construction solutions for strengthening the frame of a reconstructed multi-storey administrative building. The object of the study is the former Council of Ministers building in the town of Sukhum, Republic of Abkhazia.Materials and methods. During the examination of the building under study, instrumental and visual inspection methods were implemented, which revealed the significant deflection of the roof slab and of two supporting steel beams, as well as emergence of cracks in the load bearing structures and the destruction of partitions. According to the results of examination the dimensional-planning drawings and a structures’ defects list were elaborated. A spatial finite element model of the building was developed in the LIRA-SAPR software package, taking into account the developed dimensionalplanning solutions for the reconstruction of the facility under study. Loads and impacts were set taking into account the requirements of relevant design standards. The detected defects of the structures’ elements were considered.Results. The dynamic calculation of the building frame by finite element method is carried out. The calculation results analysis has shown that all three forms of oscillations are torsional, which proves the structural solutions of the building frame to be complex and requires additional calculations to ensure reliability of construction solutions. The building frame dynamic loads are set taking into account the requirements for buildings with a complex structure frame. The results of the general static calculation has shown that the load-bearing structures of a building are in operating state except for the roof slab.Discussion and Conclusions. Based on the results of a numerical experiment on modeling the operation of the roof slab, the rational solutions for its reconstruction have been developed, recommendations on considering the seismic impacts on the reconstructed building frame of the Council of Ministers have been given.

Seismic Assessment of Steel-frame Buildings Mounted with Base-Isolated System

A multi-Storey steel frame building against earthquakes has always been a challenge for structural engineering and researchers. Many seismic protection systems have been investigated overtime where the Base Isolation system has widely been used and implemented. It works on the principle of dissociation of substructure to the superstructure. In the present paper, different multi-storey steel frame buildings are evaluated, which are mounted with Lead Rubber Bearing (LRB) as a base isolator. LRB has been designed in compliance with the FEMA and ASCE guidelines. Further, a relative study is presented for evaluating the traditional fixed-base structure with a base-isolated building by performing a time history analysis. Base shear, inter-storey drift, acceleration, and displacements are examined as a result of the study. The outcome shows significant contributions towards reducing acceleration, inter-storey drift and base shear distributed over the floors. Moreover, LRB not only absorbs the seismic energy but also substantially decreases the destructive effect during an earthquake.