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Maria Eugenia Moreyra Garlock - One of the best experts on this subject based on the ideXlab platform.

  • Closed-Form Procedure for Predicting the Capacity and Demand of Steel Beam-Columns under Fire
    Journal of Structural Engineering, 2011
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock, Ignacio Paya-zaforteza
    Abstract:

    During a fire, Columns on the Perimeter of a building will be subject to moments induced by both a thermal gradient and the restraint of axial expansion by adjacent heated beams, which themselves develop axial load. These members thus act as beam-Columns because they are then subject to a combination of axial load plus moment caused by a combination of gravity plus thermal loading. This paper presents a two-pronged procedure to predict the behavior of the Perimeter Column as a beam-Column, considering both the individual member response (including thermal gradients) and the global response (including the interactions of adjacent members). All methods discussed in the paper are closed-form (i.e., they require no iteration) and can therefore be solved by using a spreadsheet or simple mathematical algorithm. The framework is sufficiently simple for use in codified structural-fire design and could be included in a reference of performance-based analysis methods for steel structures. Although this paper specif...

  • Special Issue: Commemorating 10 Years of Research since 9/11
    Journal of Structural Engineering, 2011
    Co-Authors: Maria Eugenia Moreyra Garlock, Andrea E. Surovek
    Abstract:

    This special issue of the Journal of Structural Engineering commemorates 10 years since the attacks of September 11, 2001, by focusing on research that was motivated by the impacts of events of that day. Primarily, in response to the collapse of the World Trade Center towers, the damage and collapse of neighboring structures and the damage to the Pentagon, national organizations and structural engineers have performed substantial amounts research in the area of progressive collapse with an emphasis on the response of structures to extreme loads. The ultimate objective of this research is to provide the means to design more robust and redundant structures that can resist progressive collapse under extreme loads, such as blast, impact, and fire, by considering both member and system response to extreme events and increasing the database of experimental results. This special issue focuses on some recent research in these areas. The papers and their list of references combined are a rich source of information and a state-of-the-art representation of structural engineering for extreme loads. The first seven papers in this issue focus on the topic of resiliency and robustness. Although the Department of Defense (DoD) has been focused on collapse prevention since before 9=11, they have done significant research since that event. The first paper, by Stevens et al., highlights the work that lead to development of the Unified Facilities Criteria (UFC) 4-023-03, Design of Buildings to Resist Progressive Collapse. Both experimental and analytical investigations of progressive collapse are considered in the next three papers. Sadek et al. focus on steel and concrete moment frames with a focus on beam Column subassemblages in the event of a Column removal. Sasani et al. present results of an experimental and analytical investigation of an 11-story concrete structure with initial damage. Williams and Williamson look experimentally and analytically at the topic of concrete bridges subjected to blast. The next three papers look more at the analytical and probabilistic side of progressive collapse. El-Tawil investigates the impact of modeling decisions on the analytical response of a 10-story steel structure and highlights the importance of the floor system in the analysis. Xu and Ellingwood look specifically at whether preNorthridge steel moment frames meet UFC requirements for structural integrity using probabilistic modeling of the connections. Kanno and Ben-Haim consider structural redundancy and its effects on robustness of the structure by considering concepts of strong and weak redundancy. The events of 9=11 pointed to large knowledge gaps in the response of structures to fire; and since then, the number of researchers and publications in this field have grown. One example is a paper by Braxtan and Pessiki, who developed the first set of experiments that examine the structural effects of removed fire protection in a fire following an earthquake. In addition to describing the experiments, finite-element analyses show how spray fire protection damage on the steel beams adjacent to the steel Column causes an increase in temperatures in the Column. Columns are integral to stability in a building; and in the case of fire, the Columns can develop unanticipated moments and thus respond as beam-Columns, which are subject to both axial loads and moments. Varma et al. tested several steel wide-flange Columns under combined axial load and moment conditions to determine their fundamental moment-curvature responses at elevated temperatures and different axial load levels. Other steel wide-flange Columns were tested to determine their inelastic buckling behavior and axial load-displacement responses at elevated temperatures. Columns on a building Perimeter respond as beam-Columns in a fire because of the thermal gradient that induces moment in the rotationally restrained Column. Quiel et al. present a two-pronged procedure to predict the behavior of the Perimeter Column, considering both the individual member response (including thermal gradients) and the global response (including the interactions of adjacent members). This closed-form procedure predicts the Perimeter Column response (demand) and capacity. Steel beams acting compositely with concrete slabs contribute significantly to the load-carrying capability of floor systems under fire. But how much does the slab contribute to the load-carrying capacity, what are the failure mechanisms, and under what conditions is the slab most beneficial? To begin to address some of these questions, Varma et al. experimentally investigated the structural behavior of thin composite floor systems subjected to combined gravity loads and fire loading. They studied parameters such as shear connection types, fire scenarios, and fire protection scenarios to evaluate the effects of each on fire performance. The companion papers by Cashell et al. study the ultimate behavior of lightly reinforced concrete floor slabs under extreme loading conditions. Particular emphasis is given to examining the failure conditions of idealized composite slabs which become lightly reinforced in a fire situation because of the early loss of the steel deck. The first paper focuses on experiments that were conducted at ambient temperature and represent an essential step toward quantifying the behavior under elevated temperature conditions. The second paper describes numerical simulation of the tests and suitable analytical models for predicting various failure conditions in slabs, including the condition of elevated temperature. This special issue is a joint effort of the Fire Protection and Structural Members Committees of the Structural Engineering Institute (SEI) Technical Activities Division. These two committees; and the Committees on Blast, Progressive Collapse, Composite Construction and Connections; were instrumental in developing the pool of authors and reviewers for this issue. We are most thankful to the reviewers, who under tight time constraints, made careful evaluations of the submitted manuscripts and provided valuable feedback. We would also like to thank Dr. Sherif El-Tawil, chief editor, for his support and efforts, as well as the ASCE production offices for their extra attention to this issue as we approached deadlines.

  • Closed-Form Prediction of the Thermal and Structural Response of a Perimeter Column in a Fire
    The Open Construction and Building Technology Journal, 2010
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    This paper proposes a simplified closed-form methodology with which to predict the thermal and structural re- sponse of steel Perimeter Columns in high-rise building frames exposed to fire. Due to their orientation in the building compartment, Perimeter Columns are heated on three sides and will develop a thermal gradient through their cross- sectional depth. Restraint of the thermal expansion associated with this gradient will cause these members to experience a combination of axial load (P) and bending moment (M), thus acting as beam-Columns. At high temperatures, the thru- depth gradient will alter the plastic capacity and mechanical behavior of the Perimeter Column, leading to plastic P-M be- havior that is not captured under the assumption of uniform cross-sectional temperature. Simplified methodologies are proposed to calculate the following: (1) the thru-depth temperature distribution that develops due to three-sided heating, (2) the gradient-induced changes in plastic capacity, and (3) the gradient-induced changes in demand (i.e. P and M). These methodologies are sufficiently simple for use in code-based design and can be implemented via a spreadsheet because they are closed-form. The individual results of each simple methodology as well as their combination are validated against the results of computational thermal and structural analysis, showing good agreement.

  • Parameters for Modeling a High-Rise Steel Building Frame Subject to Fire
    Journal of Structural Fire Engineering, 2010
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    This paper examines the level of detail and complexity that one needs to incorporate in a computational finite element (FE) model to predict the thermal and structural response of steel high-rise building frames to fire. Comparisons are made between these models in terms of accuracy and efficiency. Performance related to three parameters was examined: (1) the representation of the structural system as a 3-D full frame model versus a 2-D plane-frame model, both of which include the steel frame and the floor slab; (2) the representation of the slab in the 2-D plane frame model; and (3) the effects of modeling the temperature profile of each steel member cross-section as non-uniform (i.e. allowing a thermal gradient to develop) versus uniform. Results indicate that the 2-D plane frame model can be reasonably used in some cases to predict the performance of the Perimeter Column and floor beams framing into them in a fire-exposed high-rise moment-resisting frame (MRF) with a significant savings in analysis run...

  • A closed-form analysis of Perimeter member behavior in a steel building frame subject to fire
    Engineering Structures, 2008
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    Abstract This paper outlines a closed-form methodology that can be used to predict the increase in demand experienced by the Perimeter Columns that are part of a fire-exposed steel building frame. The two-dimensional elevation-view subassembly considered for this study includes a two-storey length of the Perimeter Column and the floor beam framing into the Column in the direction perpendicular to the building’s exterior. When heated, this beam will expand and induce bending moment and lateral deflection in the Column as well as increased axial force in the beam itself. Our proposed approach has two primary components: (1) a material model that approximates nonlinearity and considers temperature effects, and (2) a mechanical model that represents the Perimeter Column and beam interaction. These models are used to develop a simplified closed-form solution for beam axial force and Perimeter Column bending moment that may be used as part of a performance-based design for fire exposure. The simplified model solutions are compared to the results of a more complex and detailed multi-story finite element analysis model. A comparison of these results shows that the simplified model results give good estimations of structural behavior.

Spencer E. Quiel - One of the best experts on this subject based on the ideXlab platform.

  • Closed-Form Procedure for Predicting the Capacity and Demand of Steel Beam-Columns under Fire
    Journal of Structural Engineering, 2011
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock, Ignacio Paya-zaforteza
    Abstract:

    During a fire, Columns on the Perimeter of a building will be subject to moments induced by both a thermal gradient and the restraint of axial expansion by adjacent heated beams, which themselves develop axial load. These members thus act as beam-Columns because they are then subject to a combination of axial load plus moment caused by a combination of gravity plus thermal loading. This paper presents a two-pronged procedure to predict the behavior of the Perimeter Column as a beam-Column, considering both the individual member response (including thermal gradients) and the global response (including the interactions of adjacent members). All methods discussed in the paper are closed-form (i.e., they require no iteration) and can therefore be solved by using a spreadsheet or simple mathematical algorithm. The framework is sufficiently simple for use in codified structural-fire design and could be included in a reference of performance-based analysis methods for steel structures. Although this paper specif...

  • Closed-Form Prediction of the Thermal and Structural Response of a Perimeter Column in a Fire
    The Open Construction and Building Technology Journal, 2010
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    This paper proposes a simplified closed-form methodology with which to predict the thermal and structural re- sponse of steel Perimeter Columns in high-rise building frames exposed to fire. Due to their orientation in the building compartment, Perimeter Columns are heated on three sides and will develop a thermal gradient through their cross- sectional depth. Restraint of the thermal expansion associated with this gradient will cause these members to experience a combination of axial load (P) and bending moment (M), thus acting as beam-Columns. At high temperatures, the thru- depth gradient will alter the plastic capacity and mechanical behavior of the Perimeter Column, leading to plastic P-M be- havior that is not captured under the assumption of uniform cross-sectional temperature. Simplified methodologies are proposed to calculate the following: (1) the thru-depth temperature distribution that develops due to three-sided heating, (2) the gradient-induced changes in plastic capacity, and (3) the gradient-induced changes in demand (i.e. P and M). These methodologies are sufficiently simple for use in code-based design and can be implemented via a spreadsheet because they are closed-form. The individual results of each simple methodology as well as their combination are validated against the results of computational thermal and structural analysis, showing good agreement.

  • Parameters for Modeling a High-Rise Steel Building Frame Subject to Fire
    Journal of Structural Fire Engineering, 2010
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    This paper examines the level of detail and complexity that one needs to incorporate in a computational finite element (FE) model to predict the thermal and structural response of steel high-rise building frames to fire. Comparisons are made between these models in terms of accuracy and efficiency. Performance related to three parameters was examined: (1) the representation of the structural system as a 3-D full frame model versus a 2-D plane-frame model, both of which include the steel frame and the floor slab; (2) the representation of the slab in the 2-D plane frame model; and (3) the effects of modeling the temperature profile of each steel member cross-section as non-uniform (i.e. allowing a thermal gradient to develop) versus uniform. Results indicate that the 2-D plane frame model can be reasonably used in some cases to predict the performance of the Perimeter Column and floor beams framing into them in a fire-exposed high-rise moment-resisting frame (MRF) with a significant savings in analysis run...

  • A closed-form analysis of Perimeter member behavior in a steel building frame subject to fire
    Engineering Structures, 2008
    Co-Authors: Spencer E. Quiel, Maria Eugenia Moreyra Garlock
    Abstract:

    Abstract This paper outlines a closed-form methodology that can be used to predict the increase in demand experienced by the Perimeter Columns that are part of a fire-exposed steel building frame. The two-dimensional elevation-view subassembly considered for this study includes a two-storey length of the Perimeter Column and the floor beam framing into the Column in the direction perpendicular to the building’s exterior. When heated, this beam will expand and induce bending moment and lateral deflection in the Column as well as increased axial force in the beam itself. Our proposed approach has two primary components: (1) a material model that approximates nonlinearity and considers temperature effects, and (2) a mechanical model that represents the Perimeter Column and beam interaction. These models are used to develop a simplified closed-form solution for beam axial force and Perimeter Column bending moment that may be used as part of a performance-based design for fire exposure. The simplified model solutions are compared to the results of a more complex and detailed multi-story finite element analysis model. A comparison of these results shows that the simplified model results give good estimations of structural behavior.

Hamid Haddadi - One of the best experts on this subject based on the ideXlab platform.

Mehmet Çelebi - One of the best experts on this subject based on the ideXlab platform.

Oren Lavan - One of the best experts on this subject based on the ideXlab platform.