Currently, progressive collapse studies are mostly conducted based on an event-independent assumption. With studies employing an event-dependent premise mainly concerning explosion or fire events, ...the aftermath of impact loading is seldom reported. Meanwhile, interactions between reinforced concrete (RC) members and superstructures under impact loading need further evaluation. In this paper, finite element models of RC structures subjected to impact loading and progressive collapse are established and validated utilizing LS-DYNA. A valuing methodology of erosion parameters for the continuous surface cap model (CSCM) considering element size is proposed in this process. The influence of impact column removal (ICR) on the progressive collapse performance of RC frame structures is studied at sub-assemblage and structure levels. The parametric study indicates that the ICR process can be described by an impact loading stage and a gravity load stage. It is also found that structures experiencing ICR are exposed to a higher risk of progressive collapse, with the downward force exerted by the impacted columns being a significant contributing factor. Dynamic analyses demonstrate that the acceleration of the column removal point (CRP) can be used to validate and quantify the downward force. The hybrid force-displacement boundary conditions of frame columns give rise to the development of downward force. Recommendations for resisting progressive collapse considering ICR are proposed based on the analytical results of the paper.
•A new threat-dependent perspective to progressive collapse research is elucidated, focusing on impact column removal (ICR).•Interactions between impacted columns and superstructures are illuminated, emphasising the influence of downward force.•The boundary conditions of frame columns suggest a new research roadmap for impact response of structural members.•The study on the effects of ICR indicates higher progressive collapse risk due to downward forces and initial damage.•Recommendations of resisting progressive collapse considering ICR are proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Progressive collapse of structures refers to local damage due to occasional and abnormal loads, which in turn leads to the development of a chain reaction mechanism and progressive and catastrophic ...failure. The tie force (TF) method is one of the major design techniques for resisting progressive collapse, whereby a statically indeterminate structure is designed through a locally simplified determinate structure by assumed failure mode. The method is also adopted by the BS8110-1:1997, Eurocode 1, and DoD 2005. Due to the overly simplified analytical model used in the current practical codes, it is necessary to further investigate the reliability of the code predictions. In this research, a numerical study on two reinforced concrete (RC) frame structures demonstrates that the current TF method is inadequate in increasing the progressive collapse resistance. In view of this, the fundamental principles inherent in the current TF method are examined in some detail. It is found that the current method fails to consider such important factors as load redistribution in three dimensions, dynamic effect, and internal force correction. As such, an improved TF method is proposed in this study. The applicability and reliability of the proposed method is verified through numerical design examples.
► We examine the tie force method used in current codes through numerical investigation. ► We identify problems in the calculation model of the current tie force method. ► We propose an improved tie force method and verify it through numerical design examples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This paper implements the multi-criteria design optimization of three-dimensional reinforced concrete frame building structures, considering aspects such as the realistic design of the elements, ...including foundations within the structural assembly, or considering the soil-structure interaction. The criteria for a more comprehensive sustainable approach are related to environmental, constructive, and durability aspects. The environmental factor is measured through CO2 emissions, considering its capture due to concrete carbonation. The use of multi-objective strategies is evident in solving the multi-criteria problem. Still, it is also proposed to formulate this problem with a single function containing all the criteria to solve it as a single-objective optimization problem. Strategies are also offered to perform multi-objective optimization based on Kriging metamodels. Several alternatives for multi-criteria decision-making are explored. The results show that multi-objective metamodel-based optimization is a good strategy for solving this problem. Alternatively, the results of the single-objective optimization of the multi-criteria problem are very satisfactory. The solutions obtained are analyzed according to the type of optimization and the decision-making criteria. Optimized solutions significantly improve the sustainability indexes compared to traditional design. Multi-criteria optimization contributes significantly to achieving these indexes. Therefore, the proposed methodology allows for the sustainable design of any reinforced concrete frame structure. It highlights the importance of integrating more encompassing formulations and advanced optimization techniques into traditional design procedures to adopt cleaner production practices in the construction sector. Finally, several promising lines of research are presented.
•Multi-criteria optimization of a 3D RC frame building structure.•Single and multi-objective optimization of the multi-criteria problem.•Kriging-based multi-objective optimization is a valuable alternative.•Single-objective optimization of multi-criteria problem is quite effective.•The proposed methodology allows for an encompassing sustainable design of RC structures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Progressive collapse is a form of disproportionate damage, which is induced by an initial local failure that propagates throughout a large portion or the entirety of structural systems. The initial ...local failure may occur anywhere in a structural system, which consequently exhibits different collapse behaviors. However, the progressive collapse resistance is an inherent property of the entire structural system regardless of any specific initial local failure. This article proposes a collapse probability index to assess the progressive collapse resistance of reinforced concrete frame structures. Such an index is capable of measuring all typical initial local failures instead of any specific ones. The collapse fragility curve is further established based on the collapse probability index, which varies with an increase in the nominal gravity. The structural redundant resistance to progressive collapse can be assessed by the fragility curve. Furthermore, a simplified assessment method is proposed to measure the collapse probability indices feasibly of reinforced concrete frames under different nominal gravity levels. The proposed method based on the collapse probability index can comprehensively evaluate the progressive collapse resistance of reinforced concrete frames which is validated through analysis of a single four-story and a group of eight-story reinforced concrete frame structures.
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IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UKNU, UL, UM, UPUK
A practical and efficient optimization procedure for designing reinforced concrete frame structures with improved resistance to seismic loading was developed. The design methodology used the ...optimality criteria method in an iterative analysis-and-redesign scheme. A damage ratio–based procedure was proposed by employing the inelastic component rotations from nonlinear dynamic analysis to strengthen the severely damaged components in each iteration. The optimization approach is intuitive, simple, and easy to apply, since only analysis tools are required. The approach was applied to optimize the seismic response of two prototype frames, and sensitivity analysis established the relationship between seismic performance and the additional material cost of strengthening. The proposed method can substantially reduce the maximum interstory drift for a slight increase of material cost, indicating that the proposed method is a feasible design procedure for improving the earthquake resistance of reinforced concrete frame structures. Also, the procedure can deal with the cases of single and multiple ground motions. The effectiveness of the proposed method was also verified through extensive time-history analyses.
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IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UKNU, UL, UM, UPUK
Reinforced concrete frames (RCFs) represent the most widespread structural typology in several high-seismic regions worldwide. Two categories of buildings can be distinguished: modern buildings ...designed following a specific seismic code and existing buildings designed only to resist to gravity loads. In both cases, the structural response of RCF may be positively or negatively conditioned by the non-structural masonry infills. Neglecting the infills in the analyses can produce an unsafe prediction of the seismic performance of a structure. In contrast, simplified modelling approaches are needed in current engineering practice, since rigorous modelling strategies, namely non-linear finite-element models, are generally incompatible with the standard hardware/software adopted by practitioners. In this paper two macro-modelling approaches, namely the equivalent diagonal strut model and a recently introduced 2D discrete macro-model, which are currently employed by engineers for predicting the seismic behaviour of infilled frames, are compared. The aim of this investigation is to highlight the influence of the modelling approach and calibration procedures on the seismic performance assessment of infilled frame structures. A recent experimental study on a 1-bay infill frame prototype and a multi-storey frame are considered as benchmark cases. The results obtained highlight the differences between the two approaches in terms of capacity curves and collapse mechanisms.
•The paper investigates the seismic behaviour of existing r/c infilled frame.•Two simplified macro-models are considered and critically compared.•Experimental tests and finite element models are compared to the macro-models.•The influence of the infill openings on the infill frame response is evaluated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
This article experimentally studies the seismic behavior of reinforced concrete frames with buckling-restrained steel plate shear walls. The buckling-restrained steel plate shear wall is connected to ...adjacent reinforced concrete beams alone by an embedded steel connector in the beams (two-side connection). This is to avoid the force transfer between the shear wall and adjacent columns with a four-side connection. Four specimens of two-story and one-bay reinforced concrete frames with buckling-restrained steel plate shear walls are designed and tested under monotonic and cyclic loads. Finite element analyses are also conducted to further investigate the advantages of buckling-restrained steel plate shear walls by comparing the behavior of reinforced concrete frames with and without buckling-restrained steel plate shear walls. The results show that the presence of buckling-restrained steel plate shear wall can not only enhance the stiffness and load-bearing capacity but also improve the ductility and energy dissipation capacity of reinforced concrete frame structures. It is found that the drift ratio of the specimens reaches 1/15 under monotonic loads and 1/30 under cyclic loads. The specimens have ductility coefficients greater than 10. Two failure modes are found for reinforced concrete frames with buckling-restrained steel plate shear walls. Damages may concentrate at the base of ground floor columns for a frame with strong connectors, while plastic hinges may form at the ends of beams and columns for frames with weak connectors.
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IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UKNU, UL, UM, UPUK
The objective of this article is to study the effects of structural nonlinear behavior on Floor Response Spectra (FRS) of existing reinforced concrete frames. This study examines how the FRS vary ...with the level of post-elastic behavior in buildings of different number of stories and masonry infill wall configurations. The effect of damping modeling assumptions is also investigated. Differences and similarities with findings from the literature are discussed. On the basis of the obtained results, a commentary on the adequacy of basic assumptions used in predictive equations proposed by different seismic codes is offered.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The Earthquake in 2005 has destroyed a large part of the Khyber Pakhtunkhwa Province (Pakistan) and Kashmir which has created questions regarding the adequacy of framed structures in order to resist ...strong motions, as due to this earthquake many buildings were damaged badly or were devastated. In order to evaluate the framed structure's performance under future expected earthquakes, a non-linear static analysis i.e. Push over analysis has been carried out. So for achieving our objective of analysing the framed structure's performance under seismic loading, a 4 storey's framed structure was selected and analysed. From the results that were obtained from this study shows that the framed structures which are properly designed under gravity will perform in a safe zone under seismic loading. Certain response parameters predicted by each pushover analysis which were obtained from Gravity & Earthquake load patterns were analysed and compared with each other for differences. The observations made from the current study clearly showed that pushover analysis results depend on three factors i.e. 1-the load path, 2-structure properties and 3-features of the ground motion. The response parameters were estimated by applying the displacement of target at the control node. The accuracy of the predictions depends mainly on the approximations involved in the theory of the procedures, structural properties and features of ground motion.
The seismic behavior factor R (noted q in the european seismic design code, the Eurocode 8) of reinforced concrete frame structures is evaluated based on comparative analysis between non-linear ...static pushover and non-linear incremental dynamic analyses. For this purpose, three-, six-, and nine-storey reinforced concrete frame structures, considered as low-, medium-, and high-rise frame, respectively, were designed according to reinforced concrete code BAEL 91 and Algerian seismic code RPA 99/Version 2003. Non-linear static pushover analysis using inverted triangular loading pattern and incremental dynamic analysis using a set of seven time-history earthquake records were carried out to compute the R factor components, such as ductility and overstrength factors, with the consideration of failure criteria at both member and structural levels. The results obtained by non-linear static pushover and incremental dynamic analyses are compared. According to the analysis results, it is observed that in the case of non-linear static pushover analysis, the value of the seismic behavior factor decreases as the number of stories increases, whereas in the case of non-linear incremental dynamic analysis, the trend observed is not the same: the value of the seismic behavior factor increases as the number of stories increases. This result shows that the value of the seismic behavior factor depends, among others parameters, on the height of a structure, which parameter is not taken into account by the seismic design codes. In the light of the information obtained from incremental dynamic analyses, it is observed that the value of the seismic behavior factor adopted by the seismic design code RPA 99/Version 2003 is overestimated, especially for low-rise frame structure. This paper also provides conclusions and the limitations of this study.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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