Multi-storey Frame Research Articles

Optimum design of nonlinear semi-rigid steel frame based on performance-price ratio via genetic algorithm

In this study, a two-stage structural optimization method is presented for multistory steel frames with semi-rigid connections. Based on the traditional optimization result in the first stage, the performance-price ratio (PPR) is introduced in the second stage to provide an idea to modify the unreasonable structural design that might occur in the price (or weight) only oriented optimization of first stage. The efficient advanced analysis (EAA) method accounting for the flexibility of beam-to-column connections, second-order effect, initial imperfection and plasticity development in members is applied in structural calculation, which is also used to acquire the ultimate capacity of structures. All schemes satisfying traditional optimization constraints in a simple design problem were obtained by exhaustive search. The price-performance relation of schemes showed that the structural ultimate capacity depends only on the rationality of members’ combination and has low correlation with the total cost. Design examples showed that the two-stage optimization considering PPR enables much more robust structural design at a slightly higher cost than the traditional optimum one.

Seismic collapse safety based optimization of steel Moment-Resisting frames

Structures must have a reasonable seismic safety margin in order to ensure life-safety as well as to prevent structural collapse caused by earthquakes. On the other hand, the cost-efficiency and economy of structures are important and integral parts of structural engineering. The main aim of the current study is to propose an efficient methodology for designing cost-efficient multi-story special steel moment-resisting frames at predefined levels of seismic collapse safety. To achieve this purpose, a seismic collapse safety assessment technique is integrated with performance-based design optimization in the present study. In order to illustrate the advantages of the proposed methodology, three design examples of 3-, 6- and 12-story special steel moment-resisting frames are presented. The numerical results show that by with a 25% increase in the optimal weight of the structures, their seismic collapse capacity increases by more than 50%.

Experimental Dynamic Response of a Multi-Story Frame Structure Equipped with Non-Conventional TMD Implemented via Inter-Story Isolation

A shaking table experiment conducted on a multi-degrees-of-freedom frame structure equipped with a non-conventional tuned mass damper (TMD) is presented. The non-conventional TMD is characterized by a high mass ratio, without adding further structural masses, and is realized via inter-story isolation. The structure top story mass of a four-story steel frame structure is isolated and converted into tuned mass, connecting to the substructure with two high damping rubber bearings placed in series. Aspects related to the dynamic structural response as well as the seismic effectiveness assessment of a non-conventional TMD are addressed. Three structural configurations are tested: the reference four-story structure, the three-story intermediate structure, and the three-story structure equipped with a non-conventional TMD. The input motion conditions considered are: white noise, sine sweep, and natural earthquakes. Through experiments, structural identification is carried out and different dynamic behaviors emerge for the configurations tested. The nonlinear effects provoked on the structure by the adopted isolators are investigated, showing high dissipative capabilities in a wide range of amplitudes of the excitation. It is demonstrated that a non-conventional TMD is a smart control strategy useful for enhancing structural vibration mitigation.

Application of the POD method to nonlinear dynamic analysis of reinforced concrete frame structures subjected to earthquakes

For the purpose of reducing computational cost, this paper presents an extension of the Proper Orthogonal Decomposition method (POD) to nonlinear dynamic analysis of reinforced concrete multistory frame structure. The material nonlinearity, due to plasticity and damaging, is modeled by the multifiber section approach. An initial expensive full model nonlinear time-history analysis is conducted for the frame structure subjected to a portion of an initial seismic base excitation. Then, POD modes are extracted and used to reduce the dynamic model for the rest of the initial base excitation or for multiple different ones. By comparing the full and reduced models, the computational cost was lowered by up to 94 % while maintaining good level of accuracy.

Extension of the improved upper-bound pushover analysis for seismic assessment of steel moment resisting frames with setbacks

Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has been recently developed. This procedure adequately estimates the response of regular and tall buildings. In this study, IUB is extended to assess the seismic response of irregular buildings with setbacks. To this end, an adjustment of the IUB lateral load distribution is implemented by integrating a third mode of vibration to control the response of these complex buildings. Fifteen multi-storey steel frames with different types of setbacks including a reference structure are used to test the accuracy of the proposed procedure by comparing its results to those from other NSPs and the nonlinear time history analysis (NTHA). The findings show the superior capacity of the extended IUB in predicting the seismic response of buildings with different levels and types of setbacks.

Seismic performance of a steel frame structure with dissipative cladding connections

In this study, a dissipative connection system for multistory steel frame structures is proposed, in which two bearing connectors are located at the top and a metal yielding dissipative connector (i.e., tapered connector) is located at the bottom of a large panel. Quasi-static test was conducted to investigate the performance of individual connectors first. Then two steel subassemblies, one having a steel frame with a large cladding panel and the other as its counterpart, a bare frame, were prefabricated and tested under quasi-static loading. Effect of the cladding panel and the proposed connections on the seismic performance of the steel frame was evaluated. It was indicated that the damage of the tapered connector was caused by the rupture of one energy dissipation plate during the fatigue loading and the hysteresis behavior of the connector was affected by the membrane effect. The proposed energy dissipation connector can improve the strength, stiffness, especially the energy dissipation capacity of the subassembly. However, the failure of both subassemblies was mainly caused by the yielding of the column foot and buckling of the beam end, therefore the cladding panel did not change the damage pattern of the steel frame. Three-dimensional (3D) finite element (FE) analysis was conducted to reproduce the tests of the connectors and the subassemblies, facilitating a better understanding of the working mechanism of the system.

Structural feasibility of braced-damper system with adaptive negative stiffness devices in yielding multi-storey steel frames

This paper investigated the structural feasibility of braced-damper system with adaptive negative stiffness devices (i.e., negative stiffness amplifying damper, NSAD) in yielding multi-storey steel frames (MSFs). The nonlinear analytical model of yielding MSFs with NSADs was established. Seismic responses of a 3-storey typical structure with and without NSAD were evaluated to illustrate the working mechanism of NSAD applied at yielding MSFs. Parametric study concerning the maximum inter-storey drift, residual deformation, and structural acceleration was conducted thoroughly to quantify the effect of NSAD. The rational distribution of NSADs was also discussed respectively for both regular and irregular yielding MSFs. Numerical results showed that the adaptive NSAD is effective in mitigating inter-storey drift, residual deformation, and structural acceleration of yielding MSFs when subjected to multiple intensities of earthquakes. It is recommended that the adaptive NSAD shall be applied at storeys with small drift response, i.e., whose stiffness (previous conclusion on elastic MSFs) and strength (new contribution of this paper on yielding MSFs) are high. In other word, the feature of NSAD that helps reducing non-arranged storey drift is also valid for the plastic scenarios.

Blended structural optimization for wire-and-arc additively manufactured beams

Current manufacturing techniques in the construction sector are slow, expensive and constrained in terms of architectural shapes. In other manufacturing sectors (such as automotive and aerospace) the use of automated construction systems significantly improved the safety, speed, quality and complexity of products. To realize real-scale structural elements for construction applications without ideally any geometrical constraints either in size or shape, the most suitable manufacturing solution for metallic elements is a directed energy deposition (DED) process referred to as wire-and-arc additive manufacturing (WAAM). The main advantage of WAAM relies on the possibility to create new shapes and forms following the breakthrough design tools for modern architecture as algorithm-aided design. At the same time, the printed part ensures high structural performances with reduced material use with respect to the conventional solution. The study presents a new approach called “blended” structural optimization, which blends topology optimization with basic principles of structural design and manufacturing constraints proper of WAAM technology, towards the realization of new efficient structural elements. The approach is applied to the case study of a I-type stainless steel beam on a multi-storey frame building. The approach could pave the way towards an efficient use of WAAM process to produce a new generation of structurally optimized elements for construction, with a more conscious use of the optimization tools and an efficient application of metal 3D printing.

Catenary effect of multi-story steel moment frame under asymmetric horizontal constraint

In terms of the structural robustness, there have been enormous studies on the catenary effect of frame structure subjected to mid-column removal. However, it will be a more common scenario that the column at various locations will probably fail so that the asymmetric constraint from the surrounding frame will be imposed upon the affected bays. Regarding the limited studies involving these issues, a static pull-down testing is hereby performed to explore the catenary effect of the multi-story frame under asymmetric horizontal constraint. Based on the full-range structural response, the floor dependency of the catenary effect and the asymmetric constraint have been confirmed to have a significant influence on the failure sequence of bolted connections, and the evolutionary histories of internal forces. The floor dependency of the catenary effect will cause the greatest deformation demand and consequently the earliest failures of connections at the 1st floor, while the asymmetric constraint will lead to the earlier ruptures of the connection adjacent to the constraint bay than those connected to the corner column. In addition, these two factors will also result in the weak catenary effect of the overall frame, featuring the negligible vertical resistance contribution from the axial tension at the 2nd and 3rd floors due to the insufficient horizontal constraint. Eventually, the high-fidelity numerical analysis including the fracture simulation is performed and validated by the excellent agreement involving the full-range force-displacement relationship, failure modes and sequences, and the local deformation.

Analysis of Multistorey RCC Frame subjected to Mainshock and Aftershock Earthquake

Abstract: Structure analysis and design are significantly influenced by earthquake. It is believed that seismic evaluation is required for the viability and serviceability of both present and future building structures. When a structure's base is subjected to a certain type of ground motion, a time history analysis is performed to examine the dynamic reaction of the structure at each time interval. The near-field earthquake ground motion verification may have specific impacts for both forward and backward directivity. The initial's velocity and displacement motions, respectively, exhibit pulse and fling-step characteristics. Therefore, it is crucial to assess how well structures built solely to withstand the primary shock would work through future aftershocks. Using modern seismic protection systems, such as base isolations or / and supplemental dampening devices, that significantly reduce building damages during main shocks and their related aftershocks is one of the appropriate solutions to this issue. Due to changes in both static and dynamic stress that take place during the earthquake process, aftershock events are set off by the primary shock. In order to better understand the ground motion features of a sizable collection of mainshock and subsequent aftershock ground motion data recorded in accelerograph stations around the region, this study reviews pertinent literature in the field. The G+9 RCC building will be used in this study to conduct a time history analysis of the mainshock and aftershock data of the Chamoli earthquake provided by the Centre for Engineering Strong Motion Research Ground Motion Database. For designing purposes, the IS 456-2000 code is taken into consideration. Live loads are measured in accordance with IS 875-part 1, and seismic zone IV is selected for analysis in accordance with IS 1893-2016. Storey drift, base shear, joint reactions, and storey displacement are just a few of the variables that can have an impact on how well a building performs. Since each of these variables has a significant impact on how a structure responds to seismic loads, they are also taken into account when evaluating the results.

Experimental study on the behavior of circular ultra-high strength concrete-filled steel tube columns subjected to unequal end moments

Concrete-filled steel tube (CFT) columns in multi-storey frames may be subjected to unequal end moments, especially during earthquakes. The behavior of ultra-high strength concrete-filled steel tube columns (UHSCFT) with concrete strengths greater than 100 MPa subjected to unequal end moments has not been studied thus far. In this study, 22 UHSCFT columns were designed and tested to investigate the influence of the end moment ratio β, eccentricity ratio e/D, and slenderness ratio L/D on the behavior of UHSCFT columns under different end moments. The results suggested that varying β from 1.0 to 0 resulted in a higher axial load-bearing capacity for the UHSCFT columns with e/D = 0.4, L/D = 7.5, whereas for β ≤ 0, the effect of the end moment ratio was marginal. Moreover, the axial load-bearing capacity generally decreased with increasing L/D and/or e/D ratios. Smaller β, smaller e/D ratios, and/or larger L/D ratios generally led to more brittle behavior in UHSCFT columns. The second order effect of UHSCFT columns with equal end moments was significant, whereas those of specimens with unequal end moments (L/D ≤ 12, e/D ≤ 0.4) could generally be neglected. Current design codes, such as EC4, AISC 360 and GB 50936, are unable to well predict the resistance to compression and bending of UHSCFT columns under unequal end moments. It was observed that the accuracy of GB 50936 would be improved by assuming K'a ≥ 1.

Issues Regarding the Appropriateness of Using Precast Reinforced Concrete Frame Structures Compared to Monolithic Reinforced Concrete Frame Structures, in Office Buildings and Residential Buildings

Abstract Given the current context at national and European level in terms of reducing skilled labour force in constructions, as well as the high level of density and traffic in large cities, there is an increasing emphasis on the possibility of shortening the duration of building the structural frames on site, reducing the number of workers or even reducing the level of noise pollution. Thus, the introduction of precast technologies in the case of office buildings and residential buildings, with multi-storey frame structure, is becoming an increasingly pressing and topical issue. The purpose of this paper is to enable structural engineers, architects and potential investors to consciously choose the type of optimal structure, taking into account a number of technical and economic aspects. In this sense, in order to highlight the main advantages and disadvantages of using multi-storey precast reinforced concrete frame structures, a comparative case study will be carried out between a precast frame structure and a monolithic frame structure, respectively.

Pull-down test and numerical validation of multi-story steel moment frame using pulley-based loading system

Regarding the structural robustness against progressive collapse, recent studies have revealed that the catenary effect is the critical resisting mechanism for the frame structures under large vertical displacement. The previous studies of the single floor beam-column subassemblies suggest that the catenary effect is greatly affected by the connection performance as well as the horizontal restraint. However, the conventional push-down testing might not appropriately represent the horizontal constraint from the surrounding bays and the vertical loading condition under the uniformly distributed gravity loads. Therefore, the static pull-down test is performed on the multi-story steel moment frame equipped with straight-reduced-section splice plates (SRSP). It is used for high deformability of beam-to-column connection. In addition, a vertical loading system using the fixed pulleys for load transferring is newly proposed for a feasible and safe loading procedure. The experimental results show that the growth of vertical resistance can be mainly attributed to the plastic hardening and the consecutive catenary effect. The maximum resistance is governed by the first rupture of SRSP at the overall chord rotation of 0.178 rad, indicating high deformability of bolted connection with SRSP. Based on the failure sequence of connections and the internal force as well as deformation response, the floor dependency of catenary effect can be significantly observed. It is characterized by the earliest failure emerging at the 1st floor, followed by the consecutive ruptures observed at the upper floors. In terms of the internal force, the vertical contribution derived from the tensile force will be gradually rising for the connection at the 1st floor, in contrast to the negligible catenary effect at the 2nd and 3rd floors. Eventually, the numerical simulation is performed based on the previously proposed material model. The simulated full-range force-displacement curve with the low percentage error of 0.8% for the first rupture displacement demonstrates the validity of the numerical model in terms of the full-range behaviors of multi-story frame structure.

METHODS OF ANALYSIS OF FRAME STRUCTURES ACCORDING TO THE EUROCODE EN 1993-1-1

In accordance with the guidelines contained in the European standard prEN 1993-1-1 (draft September 2020), the stability of multi-storey frames should be checked taking into account the influence of geometric imperfections and deformation of the structure under the applied load.

Оценка технического состояния оснований, фундаментов и железобетонных колонн каркасного здания

The paper presents the results of assessing the technical condition of foundations, foundations and reinforced concrete columns, which are elements of building structures of a multi-storey frame public building. The results of the survey of foundation structures and the characteristics of the soil base are given. The physical and mechanical characteristics of soils were determined using samples taken from the pits during the survey. The results of visual examination and field measurements of foundations in control pits are given. The results of calculating the strength of concrete foundations and columns are given. The construction and correction of the calibration dependence of the indirect non-destructive testing method was carried out on the object using the method of separation with shearing. The results of verification calculations of foundations are considered. Defects and damages of foundations were revealed. The category of technical condition of bases and foundations is substantiated. Recommendations for the repair of foundations have been developed. The design and reinforcement of columns are considered. Identified defects and damage to the columns. the results of verification calculations of columns are given. The category of the technical condition of the columns is determined. Recommendations for the repair of columns have been developed. Defects and damages of reinforced concrete columns recorded in the list of defects and damages are investigated. The main conclusions are made based on the results of a survey of foundations and reinforced concrete columns of a multi-storey frame building.

Процесс мониторинга технического состояния перекрытий и балок каркасного здания

The paper presents the results of monitoring the technical condition of floors and beams, which are elements of the building structures of a multi-storey frame building. The reasons for the need to perform a survey of a frame building, which has a long forced break in construction, are determined. It is shown that the downtime of the unfinished building and the impact of external factors had a negative impact on the technical condition of the building structures, as a result of which it became necessary to determine the suitability of the building for normal operation. For this purpose, the actual technical condition of the floors and beams of the building was determined. The methodical and instrumental equipment of work on the inspection of building structures is considered. The results of inspection of structures and reinforcement of ceilings and beams are given. The reinforcement system was checked in accordance with the current regulatory documents. The calculation of the strength of concrete floors and beams was performed. Defects and damages of ceilings and beams recorded in the list of defects and damages are investigated. The results of verification calculations of reinforced concrete floors and beams are given. The category of the technical condition of reinforced concrete floors and crossbars is considered. Recommendations for the repair of reinforced concrete floors and crossbars have been developed. The main conclusions are made based on the results of the inspection of reinforced concrete floors and beams.

Effect of beam-column joints flexibility on the seismic response of setback RC buildings designed according to the Algerian seismic code

The Algerian seismic code assumes that the beam-column joints in monolithic reinforced concrete (RC) buildings are fully rigid. However, many experiments have proven the existence of relative rotations in these connections, and then the presence of relative transfer of bending moment. The present work aims to investigate the effect of beam-column joints modelling on the global seismic behaviour of reinforced concrete (RC) moment-resisting frames buildings, designed according to the Algerian seismic code recommendations. To consider the nonlinear deformation of the connections, an analytical model developed recently is used. This model includes two important deformation mechanisms; the first one covers the slippage of the continuous reinforcement within the column, whereas the second involves slippage caused by creating bending cracks at the extremities of the beams. Three multi-storey RC frames with different setback geometry, including a reference frame, are studied considering the connections as rigid/deformable. The nonlinear static procedure or pushover analysis is used to perform a nonlinear analysis of the studied structures and the results in terms of capacity curve, target displacement, storey drift, storey stiffness and the response reduction factor are presented. The results show the necessity of considering the beam-column connection flexibility when modelling this type of building.

Seismic performance analysis of multi-story steel frames equipped with FeSMA BRBs

Buckling-restrained braces (BRBs) have been widely used in seismic prone areas around the world. However, one major problem associated with the steel BRB frames is the excessive residual deformation under strong earthquakes, mainly due to the low post-yield stiffness ratio of the steel BRBs. Recently, the community has fabricated the iron-based shape memory alloy (FeSMA) BRBs, which exhibited full hysteresis with high post-yield stiffness ratios, but the seismic behavior of the FeSMA BRB frames still remains unknown. As such, this paper conducts seismic performance analysis of multi-story steel frames equipped with the FeSMA BRBs, through a comparison with those equipped with conventional steel BRBs. Incremental dynamic analysis (IDA) is further conducted to establish the probability seismic demand models. Based on the IDA data, bivariate fragility analysis is conducted to quantify the probability of exceedance, conditioned on various limitations of the maximum and residual interstory drift ratios. According to current analysis, it indicates that both the maximum interstory drift ratios and the maximum floor accelerations are comparable between these two types of BRB frames. The major advantage of the FeSMA BRBs over the steel BRBs is that the former can better control residual interstory drift ratios.

A novel method for efficient design of frame structures equipped with nonlinear viscous dampers by using computational results of cylindrical friction damper

ABSTRACT In this paper, a new method is presented for designing nonlinear viscous dampers to improve the seismic response of multi-storey frames with braces. In this regard, a 2/3-scale three-storey steel structure is used as a benchmark case. Considering the cylindrical friction damper equipment on the bracings, the optimum slip loads are calculated for cylindrical friction damper of all stories under selected earthquakes records. For three earthquakes in optimised slip loads, the force versus the difference between velocities of two ends of cylindrical friction dampers for all stories is combined and plotted according to the velocity range for all earthquakes. Finally, the velocity–force curve is fitted and used for finding the design parameter of nonlinear viscous dampers. Similarly, the aforementioned steps are applied for El-Centro with three scales (of 50, 100 and 200% El Centro). According to the analysis results, the viscous dampers which are designed by using this approach present better performance than that of cylindrical friction dampers and considerably reduce the structural response. The values of displacement, acceleration and base shear are reduced between 63–96%, 44–85% and 14–78%, respectively. Moreover, the results of viscous dampers designed using three and one earthquakes are very similar.

Equivalent static loads for double-layered domes supported by multistorey buckling-restrained braced frames

Curved gridshells are excited not only in the horizontal direction but also experience large anti-symmetric vertical accelerations when subjected to horizontal earthquake ground motions. In addition to the coupled response, gridshells exhibit closely spaced modes and substructure-roof interaction. Nevertheless, previous studies have proposed elastic horizontal and vertical equivalent static seismic forces considering these complex dynamic response characteristics. These are determined from the input horizontal acceleration at the substructure’s roof level, an assumed acceleration distribution, nodal roof masses and amplification factors derived from the dynamic characteristics of the dome and substructure. To extend this methodology to nonlinear substructures with displacement-dependent damping devices, this paper investigates the applicability of ductility reduction factors (or Rμ factors) to estimate the inelastic response spectra and an alternative equivalent linearisation approach to compute the peak horizontal acceleration of multistorey substructures with buckling-restrained braces. This is achieved by modelling the curved roof as a rigid mass for the substructure model, and using its idealised base shear-roof displacement relationship obtained from modal pushover analyses. The peak horizontal acceleration of the substructure is then used to obtain the equivalent static loads of the curved roof using amplification factors, and the accuracies are verified against the results from nonlinear response history analyses. It was confirmed that the Rμ [Formula: see text]factors combined with the roof amplification factors provide a simple way to estimate the peak roof response with sufficient accuracy for preliminary design of domes with multistorey substructures having low post-yield stiffness.