Maria Garlock - Profile on Academia.edu (original) (raw)
Papers by Maria Garlock
Probabilistic Evaluation o-Story Steel MRF Subject to Post Earthquake Fires
Response of Structures Under Extreme Loading (PROTECT 2015), 2015
This paper investigates the structural performance of a steel moment resisting frame (MRF) subjec... more This paper investigates the structural performance of a steel moment resisting frame (MRF) subject to fire and fire following earthquake, using a methodology that is based on system level reliability analysis. The study includes probabilistic models for the quantities with uncertainty including fire load, and mechanical and thermal properties of steel at elevated temperatures. Performance of the structure is evaluated based on several different limit states, and at different fire locations. Results show that the location of fire in the frame (e.g., lower vs. upper floors and interior vs. exterior bays) affects the beam response. Compartments in the interior bays reach limit states faster than those on the perimeter, and upper floors reach limit sates sooner than lower floors. The post-earthquake damage does not affect the structural response under a fire for the considered limit states; however, fire following earthquake increases the drift demand on columns located on the perimeter of the structure.
ASCE/SEI 7 Appendix E Proposal: Performance-Based Design Procedures for Fire Effects on Structures
Using Opensees for Analyzing a 9- Story Steel Building Under Post- Earthquake Fires
Post-earthquake fires are major hazards with possible intense consequences. Civil engineering des... more Post-earthquake fires are major hazards with possible intense consequences. Civil engineering design is moving towards the concept of resilient cities, which requires buildings with structural systems to perform adequately after extreme hazards and ensure human safety. Current codes and standards in fire engineering are mainly based on design at the component level and deterministic approaches, where uncertainties in variables are not directly incorporated in the design process. Reliability-based approaches offer better means of evaluating resilience in the face of extreme hazards. But to measure resilience in an earthquake-fire multi-hazard scenario, uncertainties in the system must be captured, and nonlinear analyses must seamlessly transfer from seismic to fire analysis. This paper discusses the successes and challenges of this seamless analysis using the open source software OpenSees. A 9-story steel building with moment resisting frames is subject to fire following earthquake while being modeled in OpenSees. With the newly added fire module in OpenSees, the software has the capacity to perform structural analysis for both seismic and thermal loads. This way, system-level analysis is performed in one software and interaction of members with each other, under both seismic and fire events, is then considered together. The current constitutive material model for steel at elevated temperature does not properly capture behavior in fire following earthquake scenario. The constitutive model is therefore modified to capture effect of plastic strains, and strain reversals during heating or cooling. The resultant moment calculation is also modified to be consistent with other finite element programs and properly capture combined axial load and moment effects. The new model is used to analyze the 9-story building under two earthquake hazard levels and multiple fire locations. Results show that the new constitutive model works well. The sample analyses indicated that the subsequent fire can increase the drift of the column on the perimeter on the order of 0.5% in the lower floors and 1% in the upper floors. Total drifts in FFE did not exceed 2% (including the residual from earthquake) for the scenario studied.
Postbuckling mechanics of square slender steel plates in pure shear: Examining the role of second order effects
Structural Fire Engineering, Chapter 2 Key Terminology
A Bayesian methodology for the performance evaluation of steel perimeter columns under fire
CRC Press eBooks, Jan 9, 2014
Félix Candela, centenario: la conquista de la esbeltez = "centenary" 2010 : the achievement of slenderness : [exposición]
Low-Frequency Sine Webs for Improved Shear Buckling Performance of Plate Girders
Report, 2019
Steel plate girders are used extensively in buildings and bridges. Given shear rarely governs, mi... more Steel plate girders are used extensively in buildings and bridges. Given shear rarely governs, minimizing web thickness is desirable. However, web slenderness can enable shear buckling and fatigue problems. The traditional strategy is to use welded transverse stiffeners; yet transversely-stiffened girders are prone to fatigue cracks and difficult to fabricate at high slenderness ratios. Thus, AASHTO currently limits web slenderness to 150. Alternatively, corrugated web girders overcome these deficiencies but require robotic welding for the web-to-flange weld. Corrugated webs are also limited to small web thicknesses (6mm or less) and girder depths (less than 1.5m) given web forming limits. The authors propose an alternative web geometry, introducing low-frequency sinusoids (LFS) in the web along its length. The LFS web can be welded to the flanges using semi-automatic weld techniques currently employed by bridge fabricators. The reduced web curvature allows for a wider array of web forming techniques with much larger plate thicknesses. In a finite element study, web geometric properties such as sinusoidal frequency and amplitude are varied. Results demonstrate a significant increase in the elastic shear buckling load and ultimate strength using a wavelength equal to the depth of the girder. The results of this study show promise for improved girder durability paired with material efficiency, demonstrating that a web product with constant amplitude and wavelength could work for various girder depths up to 3m and above.
Modeling High-Rise Steel Framed Buildings under Fire
Structures Congress 2008, Oct 14, 2008
Modeling High‐Rise Steel Framed Buildings under Fire. [ASCE Conference Proceedings 314, 59 (2008)... more Modeling High‐Rise Steel Framed Buildings under Fire. [ASCE Conference Proceedings 314, 59 (2008)]. Spencer E. Quiel, Maria EM Garlock. Abstract. This study evaluates some modeling parameters that affect the use of FE ...
Ejemplo histórico del desarrollo del hormigón pretensado y su introducción en los Estados Unidos
Structural Analysis of the Cosmic Rays Laboratory
Journal- International Association for Shell and Spatial Structures, Mar 1, 2010
Felix Candela is known as one of the greatest thin shell concrete designers and builders of the 2... more Felix Candela is known as one of the greatest thin shell concrete designers and builders of the 20 th century. His works were mostly of the hyperbolic paraboloid (hypar) geometric form and mostly only 4 cm (1.5 inches) thick. The first of his many hypar shells was the Cosmic Rays Laboratory, built in 1951 on the Universidad Nacional Autonoma de Mexico (UNAM) campus in Mexico City. The shell design consists of two adjacent hypar saddles supported by a platform and stiffened by three arches. This paper explores the design of the Cosmic Rays Laboratory using finite element models. The structural behavior of the Laboratory as built is compared to one that is of a barrel form and one that does not contain any stiffening arches. Ultimately, this investigation gives insight into Felix Candela's earliest hypar design which served as both a learning experience and a prelude to his remarkable career as a shell builder.
Engineering Structures, Feb 1, 2019
There are a growing number of bridge fire events and the National Fire Protection Association (NF... more There are a growing number of bridge fire events and the National Fire Protection Association (NFPA) requires that critical structural elements of the bridge be protected from elevated temperatures due to fire. However, no guidance is given on how to protect these critical elements, nor how to identify them. Further, slender steel web plates have been shown to be vulnerable to shear buckling in fire events and recent research that indicates that the load path of shear forces in thin web plates is not well understood. The overall objective of this paper is to examine the effectiveness of stiffeners for enhancing the shear capacity of slender plates at ambient and elevated temperatures. Specifically, evaluations are made regarding the effectiveness of stiffeners for increasing the shear buckling capacity through various stiffener orientations, providing lateral restraint, and providing a load path for shear forces. In particular, the elastic shear buckling load, V cr , and the ultimate shear postbuckling load, V u , of the steel plate are examined. Finite element analyses, which have been validated with experimental data, are used as a basis for the study. The temperatures studied range from ambient to 1100 °C. This study provides some important insights on the behavior of plates under shear loads. For example, results indicate that the stiffener's role is not that of a load path for the shear forces, but one of lateral restraint, regardless of its geometric orientation. Further, it is shown that for lower temperatures a stiffener oriented along the compression diagonal (opposite to a tension field) provides the most improvement in postbuckling strength.
CRC Press eBooks, Aug 31, 2016
Compression Model for Ultimate Postbuckling Shear Strength at Elevated Temperatures
Journal of Structural Engineering-asce, Jun 1, 2017
AbstractTension field theory assumes that after elastic shear buckling has occurred, compressive ... more AbstractTension field theory assumes that after elastic shear buckling has occurred, compressive stresses in the web plate do not increase; therefore, postbuckling shear strength solely results fro...
High temperatures and bridges: Transverse stiffeners in steel girder fire performance
Bridge Structures, 2014
Vehicular accidents involving tanker trucks may initiate devastating fires that can cripple a ste... more Vehicular accidents involving tanker trucks may initiate devastating fires that can cripple a steel plate girder bridge. An observation of web shear buckling in one case study leads to a discussion on the existing understanding of this phenomenon. A closer look at the contribution of the transverse stiffeners to postbuckling shear capacity focuses on the effects of utilizing diagonal orientations of the stiffeners, as well as providing thermal insulation for the stiffeners alone. It was found that the diagonal stiffener models do not offer much improvement to the postbuckling shear strength compared to the use of the traditional vertical intermediate stiffener. Given the complexity of attaching a diagonal stiffener, it appears that the vertical stiffener is the better option. Further, providing fire resistance solely for the stiffeners was found to offer a minimal increase in the postbuckling shear strength at elevated temperatures.
Journal of Constructional Steel Research, May 1, 2020
Weathering steels are high strength low alloy steels, with a resistance to corrosion provided thr... more Weathering steels are high strength low alloy steels, with a resistance to corrosion provided through their alloying elements to form a dense layer of rust to stop further corrosion. While their mechanical material properties are well-known at ambient temperature, they have not been studied when exposed to high temperatures (as found in fires) and then cooled. This research examines mechanical properties such as Young's modulus, E, yield stress, σ y , ultimate stress, σ u , fracture toughness, and surface hardness for weathering steel (A588) and compares them to A709/A992 non-weathering steel. Such a comparison is done at ambient (as a control) and for temperatures ranging from 20 °C (70 °F), to 815 °C (1500 °F). Cooling by air and cooling by water examines the post-fire residual strength. Results show that A588 steel specimens have a slightly larger reduction in σ u at elevated temperatures compared to A709 steel specimens. Steel specimens heated up to 649 °C (1200 °F) and allowed to cool in either air or water can be expected to possess residual (post-fire) mechanical properties that are comparable to their original ambient temperature mechanical properties. Steel specimens heated to 815 °C (1500 °F) and cooled in water can experience significant increases in their residual ambient temperature σ y and σ u values, but also increasingly brittle behavior. The patina was found to offer negligible thermal protection to the underlying steel
Elevated temperature evaluation of an existing steel web shear buckling analytical model
Journal of Constructional Steel Research, Oct 1, 2014
Abstract Steel plate girders with slender webs are particularly susceptible to severe damage when... more Abstract Steel plate girders with slender webs are particularly susceptible to severe damage when subjected to high temperatures due to fire. Using nonlinear finite element (FE) models, this study examines the buckling strength of steel plate girder webs subject to fire temperatures. The models were validated with experimental results presented by other researchers, and the validation study resulted in recommendations for appropriate FE representations of material properties and boundary conditions. The elastic shear buckling stress ( τ cr ) and ultimate shear buckling stress ( τ u ) was then studied for web plates with various span-to-depth ( a / D ) ratios and a range of temperatures representing fire conditions. The results of this parametric study were compared to predictions given by the Basler–Thurlimann (BT) closed-form solution, which was originally developed to predict τ u at ambient temperature. Various representations of the elevated temperature stress, at the time of τ u , were used in the BT solution and compared to the FE results. It was found that the BT solution provides adequate predictions of τ u at elevated temperatures with appropriate substitutions for the yield stress.
Quintessentially billington: The evolution of structural art teaching at Princeton
Journal- International Association for Shell and Spatial Structures, Mar 1, 2020
Felix Candela and Heinz Isler: a comparison of two structural artists
Probabilistic Evaluation o-Story Steel MRF Subject to Post Earthquake Fires
Response of Structures Under Extreme Loading (PROTECT 2015), 2015
This paper investigates the structural performance of a steel moment resisting frame (MRF) subjec... more This paper investigates the structural performance of a steel moment resisting frame (MRF) subject to fire and fire following earthquake, using a methodology that is based on system level reliability analysis. The study includes probabilistic models for the quantities with uncertainty including fire load, and mechanical and thermal properties of steel at elevated temperatures. Performance of the structure is evaluated based on several different limit states, and at different fire locations. Results show that the location of fire in the frame (e.g., lower vs. upper floors and interior vs. exterior bays) affects the beam response. Compartments in the interior bays reach limit states faster than those on the perimeter, and upper floors reach limit sates sooner than lower floors. The post-earthquake damage does not affect the structural response under a fire for the considered limit states; however, fire following earthquake increases the drift demand on columns located on the perimeter of the structure.
ASCE/SEI 7 Appendix E Proposal: Performance-Based Design Procedures for Fire Effects on Structures
Using Opensees for Analyzing a 9- Story Steel Building Under Post- Earthquake Fires
Post-earthquake fires are major hazards with possible intense consequences. Civil engineering des... more Post-earthquake fires are major hazards with possible intense consequences. Civil engineering design is moving towards the concept of resilient cities, which requires buildings with structural systems to perform adequately after extreme hazards and ensure human safety. Current codes and standards in fire engineering are mainly based on design at the component level and deterministic approaches, where uncertainties in variables are not directly incorporated in the design process. Reliability-based approaches offer better means of evaluating resilience in the face of extreme hazards. But to measure resilience in an earthquake-fire multi-hazard scenario, uncertainties in the system must be captured, and nonlinear analyses must seamlessly transfer from seismic to fire analysis. This paper discusses the successes and challenges of this seamless analysis using the open source software OpenSees. A 9-story steel building with moment resisting frames is subject to fire following earthquake while being modeled in OpenSees. With the newly added fire module in OpenSees, the software has the capacity to perform structural analysis for both seismic and thermal loads. This way, system-level analysis is performed in one software and interaction of members with each other, under both seismic and fire events, is then considered together. The current constitutive material model for steel at elevated temperature does not properly capture behavior in fire following earthquake scenario. The constitutive model is therefore modified to capture effect of plastic strains, and strain reversals during heating or cooling. The resultant moment calculation is also modified to be consistent with other finite element programs and properly capture combined axial load and moment effects. The new model is used to analyze the 9-story building under two earthquake hazard levels and multiple fire locations. Results show that the new constitutive model works well. The sample analyses indicated that the subsequent fire can increase the drift of the column on the perimeter on the order of 0.5% in the lower floors and 1% in the upper floors. Total drifts in FFE did not exceed 2% (including the residual from earthquake) for the scenario studied.
Postbuckling mechanics of square slender steel plates in pure shear: Examining the role of second order effects
Structural Fire Engineering, Chapter 2 Key Terminology
A Bayesian methodology for the performance evaluation of steel perimeter columns under fire
CRC Press eBooks, Jan 9, 2014
Félix Candela, centenario: la conquista de la esbeltez = "centenary" 2010 : the achievement of slenderness : [exposición]
Low-Frequency Sine Webs for Improved Shear Buckling Performance of Plate Girders
Report, 2019
Steel plate girders are used extensively in buildings and bridges. Given shear rarely governs, mi... more Steel plate girders are used extensively in buildings and bridges. Given shear rarely governs, minimizing web thickness is desirable. However, web slenderness can enable shear buckling and fatigue problems. The traditional strategy is to use welded transverse stiffeners; yet transversely-stiffened girders are prone to fatigue cracks and difficult to fabricate at high slenderness ratios. Thus, AASHTO currently limits web slenderness to 150. Alternatively, corrugated web girders overcome these deficiencies but require robotic welding for the web-to-flange weld. Corrugated webs are also limited to small web thicknesses (6mm or less) and girder depths (less than 1.5m) given web forming limits. The authors propose an alternative web geometry, introducing low-frequency sinusoids (LFS) in the web along its length. The LFS web can be welded to the flanges using semi-automatic weld techniques currently employed by bridge fabricators. The reduced web curvature allows for a wider array of web forming techniques with much larger plate thicknesses. In a finite element study, web geometric properties such as sinusoidal frequency and amplitude are varied. Results demonstrate a significant increase in the elastic shear buckling load and ultimate strength using a wavelength equal to the depth of the girder. The results of this study show promise for improved girder durability paired with material efficiency, demonstrating that a web product with constant amplitude and wavelength could work for various girder depths up to 3m and above.
Modeling High-Rise Steel Framed Buildings under Fire
Structures Congress 2008, Oct 14, 2008
Modeling High‐Rise Steel Framed Buildings under Fire. [ASCE Conference Proceedings 314, 59 (2008)... more Modeling High‐Rise Steel Framed Buildings under Fire. [ASCE Conference Proceedings 314, 59 (2008)]. Spencer E. Quiel, Maria EM Garlock. Abstract. This study evaluates some modeling parameters that affect the use of FE ...
Ejemplo histórico del desarrollo del hormigón pretensado y su introducción en los Estados Unidos
Structural Analysis of the Cosmic Rays Laboratory
Journal- International Association for Shell and Spatial Structures, Mar 1, 2010
Felix Candela is known as one of the greatest thin shell concrete designers and builders of the 2... more Felix Candela is known as one of the greatest thin shell concrete designers and builders of the 20 th century. His works were mostly of the hyperbolic paraboloid (hypar) geometric form and mostly only 4 cm (1.5 inches) thick. The first of his many hypar shells was the Cosmic Rays Laboratory, built in 1951 on the Universidad Nacional Autonoma de Mexico (UNAM) campus in Mexico City. The shell design consists of two adjacent hypar saddles supported by a platform and stiffened by three arches. This paper explores the design of the Cosmic Rays Laboratory using finite element models. The structural behavior of the Laboratory as built is compared to one that is of a barrel form and one that does not contain any stiffening arches. Ultimately, this investigation gives insight into Felix Candela's earliest hypar design which served as both a learning experience and a prelude to his remarkable career as a shell builder.
Engineering Structures, Feb 1, 2019
There are a growing number of bridge fire events and the National Fire Protection Association (NF... more There are a growing number of bridge fire events and the National Fire Protection Association (NFPA) requires that critical structural elements of the bridge be protected from elevated temperatures due to fire. However, no guidance is given on how to protect these critical elements, nor how to identify them. Further, slender steel web plates have been shown to be vulnerable to shear buckling in fire events and recent research that indicates that the load path of shear forces in thin web plates is not well understood. The overall objective of this paper is to examine the effectiveness of stiffeners for enhancing the shear capacity of slender plates at ambient and elevated temperatures. Specifically, evaluations are made regarding the effectiveness of stiffeners for increasing the shear buckling capacity through various stiffener orientations, providing lateral restraint, and providing a load path for shear forces. In particular, the elastic shear buckling load, V cr , and the ultimate shear postbuckling load, V u , of the steel plate are examined. Finite element analyses, which have been validated with experimental data, are used as a basis for the study. The temperatures studied range from ambient to 1100 °C. This study provides some important insights on the behavior of plates under shear loads. For example, results indicate that the stiffener's role is not that of a load path for the shear forces, but one of lateral restraint, regardless of its geometric orientation. Further, it is shown that for lower temperatures a stiffener oriented along the compression diagonal (opposite to a tension field) provides the most improvement in postbuckling strength.
CRC Press eBooks, Aug 31, 2016
Compression Model for Ultimate Postbuckling Shear Strength at Elevated Temperatures
Journal of Structural Engineering-asce, Jun 1, 2017
AbstractTension field theory assumes that after elastic shear buckling has occurred, compressive ... more AbstractTension field theory assumes that after elastic shear buckling has occurred, compressive stresses in the web plate do not increase; therefore, postbuckling shear strength solely results fro...
High temperatures and bridges: Transverse stiffeners in steel girder fire performance
Bridge Structures, 2014
Vehicular accidents involving tanker trucks may initiate devastating fires that can cripple a ste... more Vehicular accidents involving tanker trucks may initiate devastating fires that can cripple a steel plate girder bridge. An observation of web shear buckling in one case study leads to a discussion on the existing understanding of this phenomenon. A closer look at the contribution of the transverse stiffeners to postbuckling shear capacity focuses on the effects of utilizing diagonal orientations of the stiffeners, as well as providing thermal insulation for the stiffeners alone. It was found that the diagonal stiffener models do not offer much improvement to the postbuckling shear strength compared to the use of the traditional vertical intermediate stiffener. Given the complexity of attaching a diagonal stiffener, it appears that the vertical stiffener is the better option. Further, providing fire resistance solely for the stiffeners was found to offer a minimal increase in the postbuckling shear strength at elevated temperatures.
Journal of Constructional Steel Research, May 1, 2020
Weathering steels are high strength low alloy steels, with a resistance to corrosion provided thr... more Weathering steels are high strength low alloy steels, with a resistance to corrosion provided through their alloying elements to form a dense layer of rust to stop further corrosion. While their mechanical material properties are well-known at ambient temperature, they have not been studied when exposed to high temperatures (as found in fires) and then cooled. This research examines mechanical properties such as Young's modulus, E, yield stress, σ y , ultimate stress, σ u , fracture toughness, and surface hardness for weathering steel (A588) and compares them to A709/A992 non-weathering steel. Such a comparison is done at ambient (as a control) and for temperatures ranging from 20 °C (70 °F), to 815 °C (1500 °F). Cooling by air and cooling by water examines the post-fire residual strength. Results show that A588 steel specimens have a slightly larger reduction in σ u at elevated temperatures compared to A709 steel specimens. Steel specimens heated up to 649 °C (1200 °F) and allowed to cool in either air or water can be expected to possess residual (post-fire) mechanical properties that are comparable to their original ambient temperature mechanical properties. Steel specimens heated to 815 °C (1500 °F) and cooled in water can experience significant increases in their residual ambient temperature σ y and σ u values, but also increasingly brittle behavior. The patina was found to offer negligible thermal protection to the underlying steel
Elevated temperature evaluation of an existing steel web shear buckling analytical model
Journal of Constructional Steel Research, Oct 1, 2014
Abstract Steel plate girders with slender webs are particularly susceptible to severe damage when... more Abstract Steel plate girders with slender webs are particularly susceptible to severe damage when subjected to high temperatures due to fire. Using nonlinear finite element (FE) models, this study examines the buckling strength of steel plate girder webs subject to fire temperatures. The models were validated with experimental results presented by other researchers, and the validation study resulted in recommendations for appropriate FE representations of material properties and boundary conditions. The elastic shear buckling stress ( τ cr ) and ultimate shear buckling stress ( τ u ) was then studied for web plates with various span-to-depth ( a / D ) ratios and a range of temperatures representing fire conditions. The results of this parametric study were compared to predictions given by the Basler–Thurlimann (BT) closed-form solution, which was originally developed to predict τ u at ambient temperature. Various representations of the elevated temperature stress, at the time of τ u , were used in the BT solution and compared to the FE results. It was found that the BT solution provides adequate predictions of τ u at elevated temperatures with appropriate substitutions for the yield stress.
Quintessentially billington: The evolution of structural art teaching at Princeton
Journal- International Association for Shell and Spatial Structures, Mar 1, 2020
Felix Candela and Heinz Isler: a comparison of two structural artists