Alternate Path Method in Progressive Collapse Analysis: Variation of Dynamic and Nonlinear Load Increase Factors

McKay, Aldo; Marchand, Kirk A.; Díaz, Manuel

doi:10.1061/(asce)sc.1943-5576.0000126

Cited by 73 publications

(18 citation statements)

References 1 publication

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“…The UFC guideline for nonlinear static analysis recommends the use of the Ω N dynamic increase factor (DIF) in increased gravity load combination to those bays immediately adjacent to the removed element and at all floors above the removed element (UFC, 2016). The empirical formula of DIF obtained by McKay et al (2012) and adopted in the UFC guidelines is based on the hypothesis that the controlling beam has reached its maximum allowable plastic hinge rotation capacity. Several existing studies (Ferraioli, 2019b; Liu, 2013, 2016; Tsai, 2012) have already stated that the DIF should be calculated based on the actual (as opposed to maximum allowable) plastic deformation level.…”

Section: Analytical Modeling Of Progressive Collapsementioning

confidence: 99%

Effect of fully restrained beam-to-column connection on the progressive collapse strength of steel moment frames

Salmasi

Sheidaii

Sahebalzaman

et al. 2020

Advances in Structural Engineering

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The beam-to-column connection has been identified as a key element for steel frame structures to maintain the structural integrity during progressive collapse phenomenon. In the current study, in order to assess the effects of beam-to-column connection type on the progressive collapse strength of steel moment frames, the progressive collapse behavior of a steel intermediate moment frame structure was evaluated with 10 different types of fully restrained connections. The progressive collapse strength of these buildings against sudden removal of a column was separately studied using nonlinear static alternate path method presented in Unified Facility Criteria progressive collapse guideline. To consider the nonlinear effects in the structural modeling, plastic hinges for beam and column members and connections were defined and modeled according to the ASCE 41 standard. The results of the progressive collapse analyses indicated that if the plastic hinges of connections are separately defined in addition to the plastic hinges of beams and columns, the structure will have lower progressive collapse strength, and the calculated dynamic increase factor will grow. Among the studied types of connections, the free flange connection had the best performance and the highest strength against progressive collapse.

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Section: Analytical Modeling Of Progressive Collapsementioning

confidence: 99%

Effect of fully restrained beam-to-column connection on the progressive collapse strength of steel moment frames

Salmasi

Sheidaii

Sahebalzaman

et al. 2020

Advances in Structural Engineering

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“…The M2-X -ATF model is used in these simulations since UFC 4-023-03 (DoD [2]) require that "for elements with inadequate horizontal tie force capacity, the Alternate Path method cannot be used". The following steps have to be performed to assess the DIF according to the procedures proposed in McKay et al [33] and UFC 4-023-03 (DoD [2]):…”

Section: Calculation Of Dynamic Increase Factormentioning

confidence: 99%

Assessment of Design Requirements Against Progressive Collapse in Ufc 4-023-03: Numerical Simulation

2019

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Unified Facilities Criteria (UFC 4-023-03): Design of Buildings to Resist Progressive Collapse published by the Department of Defense is one of the few design provisions that have been used around the US which provide design requirements on the basis of conventional design philosophy to the designers and the owners of the buildings against progressive collapse. These requirements are evaluated using numerical models which have been shown to be able to reasonably capture the behaviors of the buildings under column loss scenarios. A large number of case studies are conducted using validated three-dimensional macro-based models for four prototype buildings with different size, different height, different seismic detailing and different structural layouts. The simulation results show that the tie force method (TFM) is effective in protecting steel framed buildings against progressive collapse and can significantly reduce overall deformations of the structures after sudden loss of a column. However, the method for calculating the dynamic increase factor (DIF) proposed in the document is deemed problematic and thus a new energy-based approach is proposed to assess the peak dynamic displacement (PDD). The proposed method is shown to be accurate and reasonably conservative.

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“…Marjanishvili and Agnew (2006) researched the differences between the results from the AP method using linear static, nonlinear static, nonlinear dynamic, and linear dynamic analyses, finding that the evaluation criteria for the linear analyses were not conservative when compared to nonlinear analyses. McKay et al (2012) studied the dynamic and nonlinear increase factors for the AP method, proposing new methods for selecting the linear static load increase factor and the nonlinear static dynamic increase factors. While the AP method is useful for the design of structures to resist a progressive collapse, it is not used to assess the capability of a structure to resist a progressive collapse after a blast has occurred.…”

Section: Introductionmentioning

confidence: 99%

Remaining capacity estimation for buildings after an explosion using the adaptive alternate path analysis

Eskew

Jang

2019

Advances in Structural Engineering

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After an explosion, determining the remaining capacity of a structure to resist a progressive collapse can provide valuable information for emergency operations and decision makers. Condition assessments after a blast are commonly performed with a visual inspection. However, visual inspections can be time-consuming and involve putting additional personnel into harm’s way. Analytical blast analyses can estimate a structures post-blast condition, but to achieve a high level of accuracy these analyses can be time-consuming and require information regarding the blast event which may not be available at the time. This presents a need for a threat independent post-blast analysis method, which can assess for the post-blast structural condition without requiring personnel to enter the structure. The alternate path method has been used to design buildings to resist a progressive collapse; however, it does not incorporate damage outside of element failure making it unsuitable for post-blast condition assessments. Model updating using modal properties from vibration measurements has been used in structural health monitoring to estimate damage on structures, but it has not been applied to post-blast structures. In this article, a method to estimate the remaining elemental structural capacity of a post-blast structure, called the adaptive alternate path analysis, is presented. This method involves using the alternate path method to assess an updated numerical model, which incorporates the buildings’ structural damage. To demonstrate the impact of incorporating additional damage beyond elemental failure on a structure’s capacity, a simulated study is presented using simulated stiffness reductions. A blast simulation is then used to show the capacity of the updated numerical model to represent the post-blast structure and the improvements gained over using the original model. The presented methodology can be used to assess a structures potential for progressive collapse after a blast, leading to safer emergency operations.

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Alternate Path Method in Progressive Collapse Analysis: Variation of Dynamic and Nonlinear Load Increase Factors

Cited by 73 publications

References 1 publication

Effect of fully restrained beam-to-column connection on the progressive collapse strength of steel moment frames

Effect of fully restrained beam-to-column connection on the progressive collapse strength of steel moment frames

Assessment of Design Requirements Against Progressive Collapse in Ufc 4-023-03: Numerical Simulation

Remaining capacity estimation for buildings after an explosion using the adaptive alternate path analysis

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