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Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein effect of uncertainties influencing the fire resistance of structures are not explicitly considered. In this context, a probabilistic framework is presented to investigate the vulnerability of a reinforced concrete (RC) members and structure under fire loading scenario.

The RC structures exposed to fire are modeled in a finite element (FE) platform incorporating material and geometric nonlinearity, in which the transient thermo-mechanical analysis is carried out by suitably incorporating the temperature variation of thermal and mechanical properties of both concrete and steel rebar. The stochasticity in the system is considered in structural resistance, thermal and fire model parameters, and the subsequent fragility curves are developed considering threshold limit state of deflection.

The fire resistance of RC structure is reported to be significantly lower in comparison to the RC members, thereby illustrating the current prescriptive design approaches based on studies of structural member behavior to be crucial from a safety and reliability point of view.

The framework developed for the vulnerability assessment of RC structures under fire hazard through FE analysis can be effectively used to estimate the structural fire resistance for other similar structure to enhance safety and reliability of structures under such extreme threats.

The paper proposes a novel methodology for vulnerability assessment of three-dimensional RC structures under fire hazard through FE analysis and provides comparison of the structural fragility with fragility developed for structural members. Moreover, the research emphasizes to assume 3D behavior of the structure rather than the approximate 2D behavior.

The purpose of this paper is to present a simplified hybrid modeling (HYMOD) approach which overcomes limitations regarding computational cost and permits the simulation and prediction of the nonlinear inelastic behavior of full-scale RC structures.

The proposed HYMOD formulation was integrated in a research software ReConAn FEA and was numerically studied through the use of different numerical implementations. Then the method was used to model a full-scale two-storey RC building, in an attempt to demonstrate its numerical robustness and efficiency.

The numerical results performed demonstrate the advantages of the proposed hybrid numerical simulation for the prediction of the nonlinear ultimate limit state response of RC structures.

A new numerical modeling method based on finite element method is proposed for simulating accurately and with computational efficiency, the mechanical behavior of RC structures. Currently 3D detailed methods are used to model single structural members or small parts of RC structures. The proposed method overcomes the above constraints.

RC columns are very susceptible to fire, as besides the detrimental effects due to this action, second‐order effects play a significant role. In this work, the aim is to consider the ISO834 standard fire, and the focus is put on checking the proper use of a simplified method suggested on Annex B.3 of EC2 to account for the second‐order effects in RC columns.

The use of Annex B.3 of EC2 is obscure in what concerns the peak strain to be considered at the most deformed cross‐section concrete fibres, and this affects the evaluation of the second‐order moment installed in the RC column during the fire. Two hypotheses are analysed in the paper, and validated against the calculations from the advanced code SAFIR: the one where the classical limit of 3.5‰ is assumed for the peak concrete strain in compression, and a more refined compatibility of the section total strains.

The simulations demonstrate that using the simplified method with hypothesis H1 leads to unsafe conclusions. Conversely, hypothesis H2 compares much better with SAFIR predictions, and it can be rather easily adopted in real applications.

The indications provided here for the proper application of the simplified method are very useful for practical use. They overcome an unclear aspect on its implementation, not yet previously addressed.

The purpose of this study is to investigate the influence of progressive collapse under high temperature for a reinforced concrete (RC) frame. An analytical programme was analysed for a two-bay five-storey RC frame exposed to high temperature at different column locations.

The effects of high temperature protections and locations (i.e. corner, middle and intermediate) on collapse conditions and load distributions were studied for the steady-state linear analysis using finite element software.

The results show that the frame will not collapse suddenly at temperatures up to 400°C. This is attributed to an increase in the deflections of the column, which increases the lateral displacement of adjacent heated columns and governs their buckling. This indicates that the temperature rating in the column against collapse can occur at a range of 500°C-600°C compared to that of individual members. The collapse pattern of RC frames designed as ordinary moment resisting frames, and under ordinary load, combinations is based on GSA guidelines. The results for displacement, stress and axial force were collected and discussed.

The two-bay five-storey frame has been created in finite element software, and linear analysis is used to perform this study with a different temperature.

Evaluate the performance of progressive collapse of full-scale three-dimensional structure (3D) beam-slab substructures with and without the presence of reinforced concrete (RC) balconies using two concrete mixes [normal concrete (NC) and rubberized concrete (RuC)].

This study examines two concrete mixes to evaluate the progressive collapse performance of full-scale 3D beam-slab substructures with and without the presence of RC balconies using the finite element (FE) method.

The results showed that the vertical loads that affect the structures of the specimens after including the balconies in the modeling increased by an average of 29.3% compared with those of the specimens without balconies. The specimens with balconies exhibited higher resistance to progressive collapse in comparison with the specimens without balconies. Moreover, the RuC specimens performed very efficiently during the catenary stage, which significantly enhanced robustness to substantial deformation to delay or mitigate the progressive collapse risk.

All the experimental and numerical studies of the RC beam-slab substructures under progressive collapse scenarios are limited and do not consider the balcony’s presence in the building. Although balconies represent a common feature of multistory residential buildings, their presence in the building has more likely caused the failure of this building compared with a building without balconies. However, balconies are an external extension of RC slabs, which can provide extra resistance through tensile membrane action (TMA) or compressive membrane action (CMA). All those gaps have not been investigated yet.

Increasing awareness of the society and complying with design requirements of building codes for seismic safety of structures and inhabitants during severe earthquakes are the primary purpose of seismic analysis. This study aims to present the variability in seismic fragility functions for frames of different heights for the most vulnerable condition of structure using nonlinear time history analysis.

A total of 4, 8 and 20 stories reinforced concrete (RC) moment-resisting two-dimensional frames are considered for this study. Ground motions (GM) are selected as per the conditional mean spectrum and these are conditioned on a target spectral acceleration at the concern time period. RC frames are designed and detailed as per Indian standards. A concentrated plasticity approach is adopted for non-linear analytical modeling of the RC frames. Deterministic capacity limit states in terms of maximum inter-story drift ratio are considered for different damage states. Fragility functions have been derived following a lognormal distribution from incremental dynamic analysis curves. Finally, the maximum likelihood estimation of the response is obtained for fitting curves with observed fragility.

The fragility functions of the three structures reflect that under critical or extreme conditions of GM the taller buildings have higher fragility than the shorter buildings for each level of limit states even though both are designed to meet their code-level design forces.

The study is conducted on the extreme scenario of GM conditioned on the fundamental time period of each building, whereas comparison can be developed by selecting various methodologies of GM set. The probabilistic capacity model can be developed for future studies to check the fragility variation with deterministic and probabilistic capacity.

The investigation endeavors to present a comprehensive fragility assessment framework by analytical method. The outcome will be useful in the development of a disaster management strategy for new or old buildings and the response of seismic force with a variation of the building’s height. The findings will also be useful for updating the earthquake-resistant building codes for the new building construction in a similar context.

In the absence of random variables, random variables are generated by the Monte Carlo (MC) simulation method. There are some methods for generating fragility curves with fewer nonlinear analyses. However, the accuracy of these methods is not suitable for all performance levels and peak ground acceleration (PGA) range. This paper aims to present a method through the seismic improvement of the high-dimensional model representation method for generating fragility curves while taking advantage of fewer analyses by choosing the right border points.

In this method, the values of uncertain variables are selected based on the results of the initial analyses, the damage limit of each performance level or according to acceptable limits in the design code. In particular, PGAs are selected based on the general shape of the fragility curve for each performance limit. Also, polynomial response functions are estimated for each accelerogram. To evaluate the accuracy, fragility curves are estimated by different methods for a single degree of freedom system and a reinforced concrete frame.

The results indicated that the proposed method can not only reduce the computational cost but also has a higher accuracy than the other methods, compared with the MC baseline method.

The proposed response functions are more consistent with the actual values and are also congruent with each performance level to increase the accuracy of the fragility curves.

Reinforced concrete structural frames with masonry infills (infill-frames) are commonly used for construction worldwide. While the behavior of such frames has been studied extensively in the context of earthquake loading, studies related to their fire performance are limited. Therefore, this study aims to characterize the behavior of infill-frames under fire exposure by presenting a state-of-the-art literature review of the same.

Both experimental and computational studies have been included with a special emphasis on numerical modeling (simplified as well as advanced). The cold behavior of the infill-frame and its design requirements in case of fire exposure are first reviewed to set the context. Subsequently, the applicability of numerical modeling strategies developed for modeling cold infill-frames to simulate their behavior under fire is critically examined.

The major hurdles in developing generic numerical models for analyzing thermo-mechanical behavior of infill-frames are identified as: lack of temperature-dependent material properties, scarcity of experimental studies for validation and idealizations in coupling between thermal and structural analysis.

This study presents one of the most popular research problems connected with practical and reliable utilization of numerical models, as a good alternative to expensive traditional furnace testing, in assessing fire resistance of infill-frames. It highlights major challenges in thermo-mechanical modeling of infill-frames and critically reviews the available approaches for modeling infill-frames subjected to fire.

The objective of the study is to examine the response of reinforced concrete (RC) structures subjected to Near-Fault Ground Motions (NFGM) and highlight the importance of considering various factors including the influence of the relative geographical position of near-fault sites that can affect the structural response during an earthquake.

In this paper, the response of a four-storey RC building subjected to NFGMs with varied characteristics like hanging wall and footwall in conjunction with directivity and the effect of pulse-like ground motions with rupture direction are investigated to understand the combined influence of these factors on the behavior of the structure. Furthermore, the capacity and demand of the structural element are investigated for computing the performance ratio.

Results from this study indicate that the most unfavorable combinations for structural damage due to near-fault ground motion are the hanging wall with forward rupture, the fault normal component of ground motions, and pulse-like ground motions with forward directivity.

The results from this study provide valuable insight into the response of RC structures subjected to NFGM and highlight the importance of considering various factors that can affect the structural response during an earthquake. Moreover, the computation of capacity and demand of the critical beam indicates exceedance of desired limits, resulting in the early deterioration of the structural elements. Finally, the analytical analysis from the present study confirms that the hanging wall with forward ruptures, pulse-like motions, and fling steps are the most unfavorable combinations for seismic structural damage.

Urban excavations are a cause for concern in terms of the probability of damage to nearby structures. In this study, various structural and excavation parameters were investigated to determine the probability of building damage during excavations.

Finite-element analysis software was used to develop a set of valid three-dimensional models. Models were developed to assess the effects of structural parameters (building height and position relative to the excavation site) and excavation parameters (depth and support system type) on the responses of the adjacent buildings.

The new design charts estimated the damage to reinforced concrete frame buildings during excavation by focusing on the angular distortion of the building, additional shear strain on the masonry walls and additional strain and stress on columns. This study showed that the probability of damage decreased as the distance between the building and the excavation increased. By contrast, it increased when the building was located at a distance equal to the excavation depth at its edge. According to this study, the axial stress caused by the excavation of building columns does not exceed 10.9% of the compressive strength of the concrete.

The proposed design charts can replace comparable charts and provide a deeper understanding of damage potential based on key parameters. These charts are more practical than previous charts with limited parameters.