During a fire, columns on the perimeter of a building will be subject to moments induced by both ... more 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 since they are then subject to a combination of axial load plus moment due to a combination of gravity plus thermal loading. These guidelines present 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 guidelines are closed-form (i.e. they require no iteration) and can therefore be solved via spreadsheet or a 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. Alth...
ABSTRACT During a fire, columns on the perimeter of a building will be subject to moments induced... more 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 dis-cussed 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 specifically addresses the performance of columns on the perimeter of buildings, the proposed framework can be a blueprint for the performance-based analysis of other beam-columns, such as floor beams.
Low-rise office buildings constitute a large portion of the building inventory that is governed b... more Low-rise office buildings constitute a large portion of the building inventory that is governed by criteria published by the US government. In recent efforts to save costs, building owners and others in this construction sector have explored the use tilt-up construction for these facilities, which eliminates the perimeter steel framing and integrates the concrete façade into the load bearing structure. According to the criteria, many of these buildings meet the height and occupancy thresholds for which progressive collapse resistant design is required. Two major US government agencies, DoD and GSA, provide methodologies for progressive collapse analysis of common structural systems. However these guidelines include limited guidance for the design of tilt-up construction. This paper outlines a methodology for progressive collapse resistant design of tilt-up structures and discusses the increases in reinforcement needed for a prototype building.
Fire tests were performed to investigate the mechanics and capacity of steel beam-columns that de... more Fire tests were performed to investigate the mechanics and capacity of steel beam-columns that develop a thermal gradient through their depth when exposed to fire. Wide-flanged specimens were loaded axially and tested vertically in a furnace recently commissioned at Michigan State University. The placement of insulation simulated a realistic three-sided heating scenario such as that experienced by a column on the perimeter of a building frame. Specimens were tested with several combinations of load level, fire scenario, and direction of the thermal gradient (which dictates the direction of bending). The different combinations of tested parameters had a significant influence on the fire response of these columns, which all failed by full section yielding due to a combination of axial load (P) and moment (M). These columns developed bending moments in response to through-depth thermal gradients as well as a moment reversal due to a shift in the section's center of stiffness. The plastic resistance to combinations of axial load and moment was also affected by the thermal gradients such that the critical section, located in the hottest region along the column length, was where moment was the smallest (not the largest, as would be intuitively expected). The experiments and computer models showed good agreement with the predicted demands (i.e. bending moment reversal) and capacity (i.e. changes in the plastic P-M capacity).
Page 1. 115 Volume 1 · Number 2 · 2010 Parameters for Modeling a High-Rise Steel Building Frame S... more Page 1. 115 Volume 1 · Number 2 · 2010 Parameters for Modeling a High-Rise Steel Building Frame Subject to Fire Spencer E. Quiela,* and Maria EM Garlockb aHinman Consulting Engineers, 225 Reinekers Ln., Suite 250 ...
The local buckling capacity of fire-exposed steel cross sections is affected by the reduction in ... more The local buckling capacity of fire-exposed steel cross sections is affected by the reduction in strength and stiffness associated with an increase in steel temperature. Using a stress-based approach, simple continuous equations that account for these reductions are proposed in this paper to calculate the ultimate strength of thin steel plates (i.e. idealized webs and flanges) at elevated temperature. Calculations
This paper outlines a closed-form methodology that can be used to predict the increase in demand ... more 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 twodimensional 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.
Plastic Axial Load and Moment Interaction Curves for Fire-Exposed Steel Sections with Thermal Gra... more Plastic Axial Load and Moment Interaction Curves for Fire-Exposed Steel Sections with Thermal Gradients. [Journal of Structural Engineering 134, 874 (2008)]. Maria EM Garlock, M.ASCE, Spencer E. Quiel. Abstract. Current practice ...
During a fire, columns on the perimeter of a building will be subject to moments induced by both ... more 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 since they are then subject to a combination of axial load plus moment due to a combination of gravity plus thermal loading. These guidelines present 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 guidelines are closed-form (i.e. they require no iteration) and can therefore be solved via spreadsheet or a 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. Alth...
ABSTRACT During a fire, columns on the perimeter of a building will be subject to moments induced... more 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 dis-cussed 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 specifically addresses the performance of columns on the perimeter of buildings, the proposed framework can be a blueprint for the performance-based analysis of other beam-columns, such as floor beams.
Low-rise office buildings constitute a large portion of the building inventory that is governed b... more Low-rise office buildings constitute a large portion of the building inventory that is governed by criteria published by the US government. In recent efforts to save costs, building owners and others in this construction sector have explored the use tilt-up construction for these facilities, which eliminates the perimeter steel framing and integrates the concrete façade into the load bearing structure. According to the criteria, many of these buildings meet the height and occupancy thresholds for which progressive collapse resistant design is required. Two major US government agencies, DoD and GSA, provide methodologies for progressive collapse analysis of common structural systems. However these guidelines include limited guidance for the design of tilt-up construction. This paper outlines a methodology for progressive collapse resistant design of tilt-up structures and discusses the increases in reinforcement needed for a prototype building.
Fire tests were performed to investigate the mechanics and capacity of steel beam-columns that de... more Fire tests were performed to investigate the mechanics and capacity of steel beam-columns that develop a thermal gradient through their depth when exposed to fire. Wide-flanged specimens were loaded axially and tested vertically in a furnace recently commissioned at Michigan State University. The placement of insulation simulated a realistic three-sided heating scenario such as that experienced by a column on the perimeter of a building frame. Specimens were tested with several combinations of load level, fire scenario, and direction of the thermal gradient (which dictates the direction of bending). The different combinations of tested parameters had a significant influence on the fire response of these columns, which all failed by full section yielding due to a combination of axial load (P) and moment (M). These columns developed bending moments in response to through-depth thermal gradients as well as a moment reversal due to a shift in the section's center of stiffness. The plastic resistance to combinations of axial load and moment was also affected by the thermal gradients such that the critical section, located in the hottest region along the column length, was where moment was the smallest (not the largest, as would be intuitively expected). The experiments and computer models showed good agreement with the predicted demands (i.e. bending moment reversal) and capacity (i.e. changes in the plastic P-M capacity).
Page 1. 115 Volume 1 · Number 2 · 2010 Parameters for Modeling a High-Rise Steel Building Frame S... more Page 1. 115 Volume 1 · Number 2 · 2010 Parameters for Modeling a High-Rise Steel Building Frame Subject to Fire Spencer E. Quiela,* and Maria EM Garlockb aHinman Consulting Engineers, 225 Reinekers Ln., Suite 250 ...
The local buckling capacity of fire-exposed steel cross sections is affected by the reduction in ... more The local buckling capacity of fire-exposed steel cross sections is affected by the reduction in strength and stiffness associated with an increase in steel temperature. Using a stress-based approach, simple continuous equations that account for these reductions are proposed in this paper to calculate the ultimate strength of thin steel plates (i.e. idealized webs and flanges) at elevated temperature. Calculations
This paper outlines a closed-form methodology that can be used to predict the increase in demand ... more 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 twodimensional 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.
Plastic Axial Load and Moment Interaction Curves for Fire-Exposed Steel Sections with Thermal Gra... more Plastic Axial Load and Moment Interaction Curves for Fire-Exposed Steel Sections with Thermal Gradients. [Journal of Structural Engineering 134, 874 (2008)]. Maria EM Garlock, M.ASCE, Spencer E. Quiel. Abstract. Current practice ...
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