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Cross-sectional dimensions of the beams and columns of model structures: (a) 5-m span model; (b) 10-m span model
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Structures are often subjected to vehicle collision, which can be accidental or intentional as in the case of a terrorist attack. This study investigated the performance of three-story steel moment frames with span length of 5 and 10 m subjected to vehicle collision at a first-story column using finite-element analysis software. The progressive col...
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Basically, columns of CFST (Concrete-filled steel tube) are a common technique to increase the carried compressive forces in the frame. These columns are very effective method of composite building. The behaviors of these columns due to several various loading types have been well studied. This study investigated the CFST columns in order to advanc...
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... Detailed design guidelines for alternative load path analysis are described in the publication [6]. Examples of complex numerical analyses can be found in publications: [7][8][9]. ...
The paper presents the analysis of progressive collapse in a building under impact load. The building with four-story frame structure and underground car park is taken into consideration. The car park structure consist of reinforced concrete columns. The above-ground part of the building consist of reinforced concrete slabs supported by steel columns. Two cases are considered: the impact of a car on a reinforced concrete columns of the car park, and the impact of the car on a steel columns on the ground floor. The computational analysis are carried out using two methods: equivalent static approach, and simplified dynamic approach according to EN 1991-1-7, Eurocode 1-Actions on structures-Part 1-7: General actions-Accidental actions, 2. Mitigation of the risk of progressive collapse in steel and composite building frames under exceptional events, D3-1: Design recommendations against progressive collapse in steel and steel-concrete buildings. In the equivalent static method the impact force is replaced with an equivalent static force, and internal forces in the structure are calculated using static analysis. In the dynamic approach, the structure is loaded with a dynamic force from the vehicle impact, and dynamic analysis is conducted using a linear-elastic material model. The calculation results include: values of internal forces, values of stress ratio, values of displacement at certain points (nodes) in the structure. Additionally , the paper presents the guidelines of designing buildings for the effects of vehicle impact included in EN 1991-1-7.
... Studies (Ferrer et al., 2010;Sharma et al., 2012;Al-Thairy & Wang, 2014) reveal that direction of impact, the location of impact, the change in kinetic energy, and the properties of the impactor object, such as mass and velocity, influence the behavior of the impacted structure, thus, resulting in variations in the distribution of the forces in other structural elements of the building. Kang and Kim (Kang & Kim, 2015) investigated building performance against progressive collapse using both threat-independent and threat-dependent methods, finding that the alternate path method, involving column removal, lacks reliability and accuracy when facing the potential of high-velocity impacts in a building. Sohel et al. (Sohel et al., 2020) investigated vehicle impacts with varying velocity and mass, focusing on axial force ratios. ...
Civil structures are subjected to accidental or intentional impacts, which can lead to an initial failure, and subsequently to a tragic progressive collapse. While progressive collapse studies have seen significant growth, most of the current research focuses on threat-independent approaches, neglecting the explicit consideration of impact effects on the building's behavior. In this study, we investigate impact-induced progressive collapse, exploring various scenarios with different mass and velocity parameters. By doing so, this study aims to highlight the importance of explicitly accounting for impacts in progressive collapse analyses and provide possible solutions for safer structural design. For comparison, code-based dynamic column removal analyses are also performed and the results are compared and contrasted. Based on the obtained results, location of the damage and height of the building have important influence on the progressive collapse response in both threat-independent and threat-dependent approaches. Velocity plays a significant and critical role compared to mass in increasing the kinetic energy applied to the building, and the vertical vibration in the node on top of the impacted column. With the lower impactor velocities, the threat-independent method can be used safely, however, for the higher velocities the progressive collapse potential is much higher in threat-dependent approach compared with code-based dynamic column removal.
... As indicated, the numerical peak impact force was slightly higher than that of the test with an error of less than 10%, and the impact duration was approximately identical. Additionally, the numerical and test deformation patterns of the vehicle are also in good agreement, as shown in (Ganesan et al., 2021;Kang et al., 2015;Xiang et al., 2021;Zhou et al., 2022), including the collision contact and the consequent structural collapse. For RC frame subjected to vehicle impact, strong non-linear behavior is only observed at the columns directly impacted by the vehicle and the adjacent structural members to which a large impact force is being transferred. ...
The objective of this study is to develop a simplified numerical model that can be used to accurately and quickly conduct the collapse analysis of reinforced concrete (RC) frames impacted by vehicle in 45-degree oblique direction. The simplified numerical model included introduce of a simplified RC frame and a simplified vehicle. For the simplified RC frame, a mixed modeling technique was used in which structural components that experienced serious damage were simulated using detailed elements, while the retained structural components were simulated by macro elements. A constraint algorithm of nodal rigid body in LS-DYNA was adopted to guarantee the displacement compatibility of two kinds of element. For the simplified vehicle model, the spring-mass system was improved on the basis of the energy conservation principle to represent the vehicle in a 45-degree oblique impact. Combining the simplified RC frame model and vehicle model, the impact response of RC frame subjected to vehicle impact was studied and compared with the results of detailed RC frame model impacted by detailed vehicle. The validation confirmed that these introduced simplifications could significantly improve the computational efficiency and ensure the computational accuracy for the collapse analysis of RC frame subjected to vehicle impact.
... The performance of steel structures with moment frames under impact loading has been analysed by few researchers [29][30][31]. The results from nonlinear dynamic analyses show that the effect of impact waves on a given target structure is much greater compared to equivalent quasi-static loads. ...
... To identify and measure the damage state for the examined structure under various collision scenarios, the four-level performance criteria for extreme loads, as specified in ASCE, were taken into account in the present study. The latter specifies the failure type and its classification in "light", "moderate" or "severe" damage states, as summarized in Table 4 [29]. ...
The progressive collapse of structures subjected to a truck collision with ground floor columns is numerically investigated in this paper. For this purpose, a four-story steel building with a dual system (including an intermediate steel moment frame, with a special concentric steel bracing system in the longitudinal (x) direction, and an intermediate steel moment frame in the transversal (y) direction) is considered. The structure, which was designed according to AISC, ASCE7 and 2800 Iranian seismic standard guidelines, is located in seismic-prone area and subjected to eight different truck collision scenarios. The nonlinear dynamic analyses carried out in ABAQUS on a three-dimensional finite element (FE) numerical model include variations in collision features (i.e., mass and speed of the truck, the height of collision point), and are used to support the analysis of expected damage. The presented results confirm that increasing the truck mass and speed increases damage entity for the column and structure. Several influencing parameters are involved in damage location and progressive evolution. The height of the collision point from the ground also significantly affects the magnitude of structural damage, especially in terms of stress peaks in the panel zones for the target column. Finally, the perimeter columns are more vulnerable to impact than corner columns, in structures with dual system as with the examined four-story building. The presence of a bracing system parallel to the impacting vehicle can in fact reduce the deformation—and thus the expected damage—of the adjacent target column. Most importantly, it is shown that the numerically reproduced collision scenarios (and the associated damage configurations) based on truck impact are significantly more severe than those artificially created based on the conventional column removal method (i.e., alternate path (AP) analysis approach), which confirms the importance of more sophisticated numerical calculation procedures to investigate and assess the progressive collapse of structures.
... In recent decade, there has been a lot of focuses on the influences of high-temperatures on structural elements of SMRF such as beams and columns. [13][14][15][16][17][18][19][20][21][22][23][24][25]. Rahnavard and Thomas [13] evaluated various numerical modelling methodologies for bolted and welded connections subjected to hightemperature loading. ...
The prevalence of various types of experimental and numerical uses in this area is mostly due to the significance of welded connections in the behaviour of steel moment-resisting frames (SMRFs). The most effective conditions that aggravates the undesirable performance of welded connections is high-temperatures. With regard to conduct analytical research, three types of welded angle seat connections will be selected for finite element modeling (FEM) in ABAQUS software to investigate the performance of them under high-temperature loading. The parameters of increasing thickness, length of welded angle seat connection, and simple connection with angle by adding stiffener are assessed. For this aim, a flexible angle seat connection is used to help the web angle. The characteristics of the web angles and seats are determined based on the features of the beam. Based on the results, the sample COL-ST10-L50-SP15 has the best performance versus other samples. In this sample, beam to column connection is welded angle seat with dimensions such as 10 mm thickness, 50 mm length and 15 mm thickness of stiffener. The displacement of this sample is 502.52 mm under heat conditions. It means that the displacement ratio of the mentioned sample is 18.25% versus reference sample. Therefore, the results showed that by increasing the heat, two important factors should be suggested in the design of steel connections. These factors such as increasing the force due to longitudinal expansion and decreasing the strength and stiffness are considered.
... The analysis of robustness steel moment frame under vehicle impact were presented in [10]. A various speed of vehicle was adopted to assessing structural response. ...
The current design codes recommend designing the building structures based on the assumption avoiding the disproportionate to the initial cause damage during accidental situation. As a main strategy to mitigate a progressive collapse an alternative load path method is recommended. Flush and extended bolted end-plate joint to connect beam-to-column were experimentally tested. Hierarchical validation of joint FEM models based on experimental test results were performed. The numerical dynamic analysis by finite element method of selected steel frame under column loss scenario is presented. The planar 2D model of frame were used. Shell elements for beams and columns and solid elements for joints were employed respectively. Nonlinear material and geometry were applied in the analysis. Johnson-Cook model was used to describe the change of steel parameters by dynamic Increase Factor (DIF). The Rayleigh model to include the damping effects in the analysis was used. The dynamic analysis was performed with the use of Abaqus/Explicit module. Main conclusion of presented research it that to achieve the required level of robustness, bolted beam-to-column joints with extended end-plate of thickness more than 15 mm should be used.
... The body of the literature adopts threat-independent approach (mainly dynamic column removal) for study of impact-induced progressive collapse. The finding of these studies should be very carefully used for strengthening and retrofitting purposes, since as highlighted in several studies [127,128,129,130], structural response in impact-induced progressive collapse can be very different compared with threatindependent dynamic column removal. The structures that meet the code-based requirements may collapse when subjected to impact of a vehicle. ...
Abnormal events, that are unforeseeable low-probability and high-impact events, cause local failure(s) to structures that can lead to the collapse of other members and, eventually, to a disproportionate progressive collapse. Ordinary design procedures, which are usually limited to gravity and seismic/wind loads, are inadequate for preventing the progressive collapse. Therefore, a focus on strengthening and retrofitting techniques to mitigate progressive collapse is necessary. Parameters such as topology of the structure, nature of the triggering event, size of the initial failure, typology of the collapse and seismic design requirements affect the strengthening and retrofitting strategy. A discussion on the impact of these parameters on strengthening strategy is first presented. Then, a comprehensive review on strengthening and retrofitting techniques to mitigate progressive collapse is provided. The paper concludes with an ambitious comprehensive list of issues covering different aspects of future research agenda.
... The behaviour of joints under impact loading has also been investigated using experimental approaches. Grimsmo et al. [28] performed tests impacting axially the column of a cruciform beam-to-column joint (Gravitational dynamic loads) while Rahbari et al. [31] and Kang et al. [32] performed lateral impact tests, impacting the column orthogonally to the main axis. Impact tests performed using dropping masses have been carried out in [33][34][35][36]. ...
Modern standards require the design of resilient structures, highlighting the need for systems able to assure life safety and an easy repairability. Indeed, a resilient design includes the conception and the realization of a structure able to sustain accidental or exceptional events with limited and easy-to-repair damages. Within this framework, steel Moment Resisting Frames (MRFs) equipped with Slide Hinge Joints, have proved to be extremely efficient for the seismic performance and damage avoidance. However, to date, limited knowledge exists on their behaviour under exceptional events and significant research efforts are still required.
In order to provide a contribution to fill this gap, this paper focuses on the behaviour of SHJs with Symmetric Friction Dampers (SFDs) under drop-weight impact. SHJs are normally designed to act as the dissipative fuse of MRFs under seismic loadings. However, they can be also effectively exploited to improve the robustness of steel buildings through the increase of the local ductility, which may ensure also the activation of catenary effects in beams and tying forces.
The response of MRFs equipped with such a joint under extreme dynamic loading condition is not straightforward. It requires a deep knowledge of their behaviour as a function of the strain rate. In this paper the results of six drop weight impact tests on double-sided SHJs are presented and a 3D finite element model is developed in ABAQUS software. A parametric analysis is then performed to investigate the influence of the key parameters affecting the joint behaviour, namely: the impact velocity, the impact mass and the impact energy.
In order to characterize the joint behaviour under impact, the paper provides a correlation between the dissipation rate of the joint, under impact, and the input energy. The work is limited to a geometric range and to the joint typology here considered, however, the methodology and the results can be generalized.
Overall, the joints perform better under higher velocities rather than higher masses due to strain rate effects. However, a clear correlation between the DIF and the velocity of rotation of the joint is difficult to establish.
... Heng et al. [23] demonstrated that a single column with pinned or fixed ends cannot be used to accurately represent the response of structural columns under impact loads. Some studies have focused on steel structures subjected to impact loads using numerical investigations [24,25] and sub-structure experiments [26][27][28]. However, research on overall structural impact tests, especially on steel garages subjected to vehicular collisions are few. ...
Steel garages are widely used in urban areas to park cars, and are often subjected to vehicular collisions. Currently, few design standards provide reasonable guidelines for the accident resistance of the garages. This study experimentally and numerically analyzes the structural response of steel garages subjected to vehicular collisions. First, four impact tests were performed on 1:5 scale steel garages considering different impact directions and parking loads, and the impact force and displacement at the impact point were analyzed. The results indicated that the structural side column suffers severe local damage when subjected to impact loads along its weak axis. Subsequently, multi-scale finite element models were developed and verified against the test results. Finally, the collision process of an equivalent truck with a full-size steel garage was simulated, and the structural response of the garage was investigated considering different collision speeds, collision masses, and garage load levels. The results showed that the garage load level does not have a significant influence on the structural behavior of the garage. The amount of energy absorbed by the steel garage decreased with the increase in the collision speed and collision mass, and was between 54.49% and 67.03%.
... As a result, a new framework based on the probabilistic demand model and the shear force capacity of the RC bridge's base was presented to reduce the damage under impact loads. Kim and Kang [22] investigated the effect of a vehicle impact on the corner column of a SMRF structure with spans of 5 and 10 m. The results showed that with the increase of vehicle velocities to 80 and 120 km/h, a progressive collapse occurred in the mentioned structure. ...
... The vertical displacement has enhanced by increasing the height of structural models. Furthermore, the progressive collapse potential of the SMRFs is evaluated in scenarios of dynamic instability velocities based on vehicle impact and the procedure of the Alternate Path Method (APM) stated in the Unified Facilities Criteria guideline (UFC) [22,51]. The influence of local failure on structural parts leads to global collapse of the entire structure, which is referred to as progressive collapse. ...
In recent decades, researchers have been examining the behavior of structures subjected to abnormal loadings such as fire, blast, and vehicle collision. Extreme actions like the impact force of light and heavy vehicles on the external column of steel buildings, whether accidentally or purposely, are an essential research topic among the many impact loading scenarios. Since the impact loads induced by vehicle collisions on external building columns are rarely considered in the design procedure, so, the effect of these loads on the nonlinear performance of structures needs to be investigated thoroughly by using nonlinear dynamic time history analyses and fragility curves. In this study, 2D steel moment-resisting frames (SMRFs) with 2, 5, 8, and 12-story with an intermediate ductility are designed for gravity and seismic loads. Then, nonlinear dynamic time history analyses are performed using OpenSees software under the impact loads induced by light and heavy vehicles collisions with corner column of mentioned frames. Next, Fragility curves are proposed based on the various damage levels for interpretation of probabilities. The results of the probabilistic analyses showed that among the studied frames, mid-rise 8-story frame had more collapse capacity and low-rise 2-story frame had less collapse capacity against vehicle impact. For example, the average collapse velocity for low, medium, and severe damage levels of a 2-story frame is equivalent to 27, 37 and 69 km/h under the impact of a light vehicle collision, respectively.
