Multi-story Frame Buildings Research Articles

COMBINED SLAB-PILE FOUNDATION

Solid reinforced concrete slab foundations are commonly employed in the construction of multi-story frame and panel buildings on natural grounds, as well as in industrial structures such assilos, elevators, chimneys, steel reactors, and more.One significant advantage of monolithic foundations is their ability to be used on weak and uneven ground bases. These foundations can distribute uneven loads over a considerable area, redistributingthem to equalize the inevitable differential settlements of individual foundations. On soft and uneven soils, slab foundations are not only used to mitigate deformations but also to protect against highgroundwater, creating what is known as a "floating" foundation.It has been demonstrated that the combined slab pile foundation (CSPF) is an effective development in the field of foundation construction. CSPF constitutes a foundation system comprising a "pile field – slab grillage – soil base," where piles bear a portion of the building load, and the slab grillage functions as a foundation slab. CSPF can be interpreted as a monolithic slab supported by piles of various types arranged in the form of a pile field, strips,clusters, or individual piles. Various types of piles, including "barrette" piles, can be used for CSPF foundations.Considering the soil resistance beneath the slab grillage in the deformation calculations and loadbearing capacity of combined slab-pile foundations provides a reserve for enhancing their economic efficiency. This includes reducing the number ofpiles, lowering the consumption of steel reinforcement, and decreasing the thickness of the grillage.However, the implementation of CSPF in construction is hindered by the limited theoretical research, necessary regulatory framework, and design experience for such structures.The determination of design parameters for CSPF is carried out using the method of successive approximations. By specifying the area of the slab grillage and defining the pile length and spacing, the number of piles in the foundation, the settlement ofan individual pile, and the design load on the pile are calculated (initially assuming that all piles bear 70-80% of the total load).

Exploring influence of eccentricities and axis deviations on stress and strain state of reinforced concrete columns in multi-story frame buildings

Exploring influence of eccentricities and axis deviations on stress and strain state of reinforced concrete columns in multi-story frame buildings

Behavior of a Multi-Story Steel Structure with Eccentric X-Brace

Eccentrically Braced Frames (EBFs) outperform moment-resisting frames in seismically active regions because of their strength, stiffness, energy dissipation, and ductility. Conventional bracing systems, such as X, Y, V, or K types, are utilized to enhance structural integrity. This study employs computational modelling to analyze multi-story steel buildings featuring an eccentric X-brace system. In this investigation, 120 multi-story steel frame buildings were selected. These multi-story structures comprise six-, nine-, and twelve-story geometries. ETABS built a full-scale FE model of multi-story structures. The study's parametric variables are the X-brace eccentricity, steel X-brace section size, and X-braced placement. Steel X-braces may have an eccentricity of 500, 1000, or 1500 millimeters. The ETABS model was validated when its findings matched experimental data. According to the data, the eccentric X-brace increases top-story displacement more for 6-story multi-story structures than for 9- and 12-story ones. Eccentric X-braces reduced lateral stiffness, allowing more significant floor movement. Eccentric and diagonal braces offer less lateral rigidity than concentrically braced frames due to their flexibility. Eccentricity reduces stiffness, even if the X-braced component has a larger cross-section. EBFs may migrate horizontally. Since the EBF absorbs more energy, changing the X-brace section size and eccentricity affects its ductility.

Accurate Estimation of Inter-Story Drift Ratio in Multistory Framed Buildings Using a Novel Continuous Beam Model

This study presents a novel method for accurately predicting the dynamic behavior of multistory frame buildings under earthquake ground motion. The proposed method allows approximately estimating the inter-story drift ratio, a crucial parameter strongly associated with building damage, its distribution along the building height, and its maximum value location. An equivalent continuous beam model with a rotation at the base, consisting of a combination of a shear beam and a flexural beam, is proposed to achieve this. This model derives closed-form solutions for the building’s dynamic characteristics. The lateral deformations along the height of frame buildings subjected to a given earthquake load, particularly the inter-story drift ratio profiles, and the maximum inter-story drift ratio parameter, are investigated. The proposed continuous model requires two dimensionless parameters: the lateral stiffness ratio (α) and the rotation at the base (θ), representing the drift ratio of the first story. For the expression of the lateral stiffness ratio (α) coefficient, a simple equation is also proposed using the beam-to-column stiffness ratio (ρ, or Blume coefficient) associated with the framed (discrete) system. Various building models are employed to validate the proposed method, demonstrating its applicability to both high-rise and low-rise building configurations. With the results obtained, it is shown that the proposed continuous model can be used not only for high-rise or multistory building models but also for low-rise building models.

Elastoplastic Quasi-Static and Impact Load Response of Steel Structure Sub-Assemblage with CFRP Strips

Presented in this paper is the outcome of an experimental investigation of the elastoplastic quasi-static and impact load response of a steel sub-assemblage constructed using a pair of hollow square section members with or without Carbon Fiber Reinforced Polymer (CFRP) strips. The sub-assemblage consists of a long structural member welded to a short member, thus representing a typical combination of a column and a beam on the face of a multi-story steel building frame. The column is subjected to a lateral quasi-static or impact load. Tests are conducted on four separate steel sub-assemblages. The first two tests are conducted with a gradually increasing flexural load applied at the midspan of the column up to the collapse condition without and with CFRP strips, respectively. Additional two tests are performed with a flexural impact load applied at midspan of the column also both without and with CFRP strips, respectively. The results of the study show that CFRP strips substantially increase the quasi-static collapse load of the sub-assemblage. However, when subjected to an impact load, the steel structure sub-assemblage with CFRP strips developed smaller strains in comparison with those without the CFRP strips. The post-impact time-dependent strains also became considerably smaller for the sub-assemblage with CFRP strips.

Numerical Modeling of Column Piers with Recessed Spliced Sleeves and Intentional Debonding for Accelerated Bridge Construction

The grouted splice sleeve (GSS) connection is considered to be an effective bending moment–resisting connection between precast RC members. This connection type has been used extensively in nonseismic regions. The application of such a connection type in moderate or high seismic regions has been investigated and considered for multistory moment frame buildings and highway bridges. A computational modeling strategy is proposed at local and global levels for developing an appropriate computational model for such a connection type using a recessed GSS connection with intentional debonding. A computational model capable of predicting the structural response under cyclic loading was developed using established material models and a forced-based beam-column element considering low-cycle fatigue of reinforcing bars, bar-slip, intentional debonding of reinforcing bars, and plastic hinge length. The proposed model for recessed GSS connections with intentional debonding was experimentally validated. The proposed model was subsequently used to obtain the seismic response of a three-column bridge bent to near- and far-field earthquakes in terms of the overall maximum drift ratio and the drift ratio at the maximum seismic force.

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.

Approximate seismic performance of full and partial self-centering systems based on spectral analysis of SDOF systems

This paper presents a performance evaluation of full and ‘partial’ self-centering (SC) systems based on spectral analysis of Single Degree of Freedom (SDOF) systems. The primary objectives are to quantify the structural performances of the full and ‘partial’ SC systems, with a wide spectrum of structural parameters under near-fault (NF) and far-field (FF) earthquakes, and to assess the accuracy of the prediction models derived from SDOF analysis to approximate the seismic performances of multi-story frame buildings. More than 1.45 million statistical response results are processed and discussed. Among other important findings, it is shown that ‘partial’ SC systems appear to be a desirable option that could control the acceleration and residual displacement responses without inducing a notable increase in the maximum displacement. Based on the available data, two sets of prediction models about the inelastic displacement demand and residual displacement response are proposed. Finally, the accuracy of the prediction models to approximate the seismic performances of multi-story frame buildings is investigated by the comparison of the responses computed from a series of braced frames with various parameters and that calculated from prediction models. The results imply that the prediction models from SDOF analysis are capable of predicting the seismic performances of the corresponding multi-story frame buildings.

Failure Risk for Frame Buildings by Certification Results: Probability Assessment

In many situations, the level of safety is established by following the guidelines set forth in rules or regulations. Engineers are accountable for giving quantitative estimates for different factors, particularly failure cost, when extra information is available, such as the owner's needs. By order of the Akimat of the city of Almaty, within 2017-2018, for the first time, a full certification of the housing stock of apartment buildings was carried out. 1847 multi-story frame buildings of various stories entered into the database. Based on the certification results, for the first time, quantitative estimates of the values of the probability of failure and reliability were obtained for frame buildings of various types. The recurrence of earthquakes is taken into account by the current

Analysis of Retrofitted Cold Formed Steel Multistory Building Frame

The cold formed steel section are increasingly used as a structural elements in low rise buildings in recent times, due to the advantages like economic production, easy transportation, low labor cost and high strength to weight ratio. In the current work a G+3 storied building frame is studied for seismic and wind load using Staad-pro software. Light gauge section is taken for beam and slab elements. The seismic analysis is carried out by Equivalent static method. After analysis the results such as story displacement, story drift, Base shear and time period are compared for different models. The building frame is also analyzed for wind load. In the current work cross bracing using Light gauge element used as a retrofitting technique. The retrofitted building frame is analyzed for wind and seismic loads and results obtained for time period, storey displacement, storey drift and base shear values are compared with the corresponding values of base frame. The results of retrofitted frame showed shortening in time period, storey displacement and story drift values in X&Z directions indicating the increased ductility, Stiffness and strength of structure. Hence the proposed retrofitting technique could be believed to achieve success results in increased strength and ductility values required by wind and seismic loading.

Experimental Investigation of Light Weight Concrete Using Sintered Fly Ash Aggregates

Light Weight Concrete (LWC) is popularly used in multi-story building frames, curtain walls, shell roofs, folded plates, prestressed or precast elements due to its lower dead load as compared to conventional concrete. Although it is less popular in practice because of its high-water absorption capacity, high cost, lack of standard specifications, and difficulty in consistent batches. This paper presents experimental study of right proportion of different size of Sintered Light Weight Aggregate (SLWA) and its influence on fresh and mechanical properties. LWC mixes were prepared with pre-soaked aggregates of different sizes 8-12mm and 4-8 mm. Their proportioning plays an important role in the density and strength of concrete. The aggregates were mixed in various proportions of 80:20, 60:40, 40:60, and 20:80, to study the fresh and harden properties of LWC. Results showed that LWC prepared with finer aggregate (4-8mm) reduces the bulk density and enhances the mechanical properties.

Providing the spatial rigidity of a multi-story wood-based frame building

Objective. The article deals with the problem of ensuring the rigidity of a frame wooden multi-story building and ways to achieve the necessary spatial rigidity, taking into account the requirements of preserving the internal volume and free space. The case of excess spatial rigidity and measures to optimize it are provided to increase the economic efficiency of the project.Methods. A simpler and less time-consuming method is the initial estimation of the cross-sectional area of the rigid elements that take the wind load. The authors propose a method for the preliminary calculation of building stiffness with subsequent adjustment in the calculation scheme.Results. The design scheme of the building frame is made in the Scad Office software package to take into account the influence of the own structure weight, the redistribution of forces and movements due to the spatial work of the frame, with subsequent adjustment of the cross-sections of rigid elements.Conclusion. The most rational and least time-consuming method for numerical calculation of stiffness is the initial estimation of the cross-sectional area of the system of rigid elements. With its help, it is possible to avoid an excess of spatial rigidity of the building and reduce the time and labor costs for selecting the location of rigid elements.

Numerical Analysis of In-plane Behaviour of Masonry Infilled Rc Frames Using Macro And Micro Models

A number of simplified methodologies have been proposed aiming at preparing numerical tools suitable for engineering application, to predict the nonlinear seismic behavior of infilled frame structures. In this paper, a 2D discrete macro element model (DMEM) for the simulation of the in-plane behavior of RC frames with infill walls, is presented, validated with an experimental result that investigate the influence of infill masonry, and evaluated with a proposed Finite Element model (FEM). In this model, the frame members are modeled by beam-column elements with lumped plasticity, while the infills contribution are modeled by plane discrete-element. As an extended study, a 2D prototype of multistory frame building, for which the results of pseudo dynamic tests are available, is investigated. The ability of the considered DMEM to predict the in-plane behavior of infill masonry elements is investigated, the merits and drawbacks are highlighted.

Experimental Estimation of Period of Vibration for Multistory RC Frame Buildings (Dept.C)

At the present lime most current building codes specify equations to be used for the calculation of the base shear and lateral loads. For the determination of these lateral loads, it is necessary to determine first the period of vibration of the building. As is known, the period of vibration of buildings can be determined theoretically or experimentally. The theoretical design values of the period ol' vibration are different from the experimental ones. Significant differences have been observed for RC multistory frame buildings and in a lesser degree for other building types such as: masonry, stone, large-paneled, and large-brains buildings. The natural periods of vibration of 53 multistory RC frame buildings have been measured by the station of Engineering-Seismometer Services (ESS). These 53 buildings have different number of stories, different dimensions in.plan (with different plan length to width ratios) and effected on different soil conditions. On the basis of these data an improved simple empirical equation relating the period of vibration and the number of stories of the building is proposed 113 estimate the fundamental period of vibration of RC multistory frame buildings. In this paper the effect of soil condition and the divisions of the building in plan on the period of vibration have been studied. Comparison of periods determined using the proposed relationships and the adopted ones shows rather well agreement.

Analysis of a Heighted Multistory Building Frame Considering Sub Base Soil Interaction Considering Lateral Forces

Analysis of a Heighted Multistory Building Frame Considering Sub Base Soil Interaction Considering Lateral Forces

Performance of flexible frame building with horizontal and 3D seismic isolation when subjected to 3D ground shaking

Seismic isolation is known to effectively mitigate the effects of horizontal ground shaking in building structures. Recent research has suggested that vertical excitation causes high-intensity slab vibrations that lead to nonstructural component damage. A detailed case study of the application of three-dimensional (3D) isolation in a realistic multi-story frame building is presented. Specifically, the seismic responses of hypothetical special concentric braced frame buildings with horizontal and 3D isolation are compared to evaluate the effectiveness of 3D isolation to mitigate the vertical ground shaking. Overall, 3D isolation with a relatively short isolation period (0.5 s) is adequate to significantly mitigate the vertical acceleration in a flexible frame building, including the amplification at mid-slab relative to adjacent columns, without compromising the usual reductions in horizontal responses.

Introducing and numerical study of a new brace-type slit damper

Slit dampers are a specific type of metallic yielding dampers, which are created by cutting a series of slits/openings in metal plates subjected to in-plane shear deformation. These slits/openings divide the metal plates into a number of links that dissipate the input energy through their plastic in-plane deformations. In this paper, a new brace-type slit damper (BSD) is proposed, and the behavior of the structure equipped with it is studied numerically. It consists of two diagonal members on both sides of a slit plate with a designed geometry for its links. Each diagonal member is pinned to the beam at one end and at the other end is only constrained against out-of-plane displacement by a gusset plate. First, the accuracy of numerical models is validated by a series of available experimental results. Then, a parametric study is performed on the frames equipped with the proposed damper to determine the effects of geometrical parameters of the damper on the behavior of the frame. After that, analytical equations are developed to predict the behavior of BSD and structures equipped with it. A simple and robust method is also proposed to simulate the behavior of all damper components with an equivalent diagonal member in structural analysis softwares. Afterwards, using this approach, several multi-story building frames equipped with the proposed damper are modeled and the seismic behavior of these frames is evaluated using nonlinear time history analyses. The results show that all studied frames have completely stable hysteresis curves under all records, and no crack was observed in the damper links at the end of the loadings. According to the obtained results, it can be concluded that the proposed damper can be used as an efficient energy dissipating device in building structures.

Strategy for the evolutionary optimization of reinforced concrete frames based on parallel populations evolving

An algorithm has been developed for optimization of reinforced concrete frames with the possibility of forming a structure with a subsequent selection of reasonable section sizes and reinforcement for it. A modified genetic algorithm is used as the main search tool. The overall optimization process is divided into two stages. At the first stage, the topology is synthesized by randomly excluding groups of structural members as well as changing the position in space of the remaining groups. At the second stage, local parallel evolving genetic algorithms are performed for the formed topologies. With a common set of variable parameters, the migration of individuals between parallel populations is not allowed. An example of optimization of the multi-story building frame is considered.

The simulation of compliance of structural joints in the calculation of multi-story frame buildings

Multi-story frame buildings in precast concrete are one of the main types of buildings being built in the country. The article considers and analyzes the results of the numerical calculation of the structural system of a multi-story frame building, made using the LIRA-SAPR software package. It has been shown that with a semi-rigid assembly of the crossbars with columns it is necessary and possible to simulate the compliance of the joints. The ratio of bending moments in spans and on supports in the crossbars of the calculation scheme depends on the coefficient of compliance (rigidity) of the joints.In its turn, the compliance of semi-rigid joints is a complex quantity, determined by the compliance of the structural elements of the joints, namely: the compliance of the embedded parts in the joined elements of the frame, the compliance of the connecting cover plate, the compliance of the welds for the connecting cover plate, as well as the compliance of the seam between the crossbar and a column filled with cement-sand mortar. An algorithm for determining the compliance of structural elements of a semi-rigid joint is given.

A Non-Linear Finite Element Modelling of Composite Beam to CFST Column Connection

The use of steel and concrete composite structure is increasing day by day especially the use of CFST columns in multistory composite building frames due to the reason that they can significantly reduce overall construction time by eliminating the need of formwork and sometimes even reinforcing bars. However, creating an ideal joint between composite beam and CFST column is quite challenging task from design, analysis and construction point of view. This connection behaviour can best be understood by its moment-rotation curve. So, here attempt has been made to model this composite connection numerically with the software which uses Finite Element Methods as a tool and results are validate. The composite connection possesses all three kinds of non-linearity, that are, geometric, material and boundary/contact nonlinearities. It is known that composite connection is nothing but the combination of bare steel connection and reinforced concrete slab with proper shear transfer mechanism and so first a bare steel connection and reinforced concrete beam is modelled. An explicit representation of connection is not necessary as long as the adequate features are captured. So attempt has been made to optimize the connection where ever it is possible. Usually design engineers design composite structure while neglecting the “composite action”in during the analysis. Sometimes these composite actions contribute much in resisting the applied load.