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John W. Lawson - One of the best experts on this subject based on the ideXlab platform.
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distributed yielding concept for improved seismic collapse performance of rigid wall flexible Diaphragm buildings
Journal of Structural Engineering-asce, 2016Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:AbstractRigid wall-flexible Diaphragm (RWFD) buildings are a common type of single-story construction in North America, Europe, and New Zealand that incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof Diaphragms. RWFD buildings have shown poor seismic performance during past earthquake events. In particular, it has been observed that the global seismic response is dominated by the response of the Diaphragm, which is mainly attributed to large in-plane Diaphragm displacements that significantly exceed the displacements of in-plane walls. In this study, the concept of distributed yielding in the flexible Diaphragm by weakening certain intermediate Diaphragm zones is explored as a cost-effective means to improve the seismic collapse capacity of RWFD buildings and mitigate their seismic vulnerability. A two-dimensional numerical framework was developed specifically for analyzing RWFD buildings and was used to evaluate the proposed concept. Results of nonlinea...
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numerical framework for seismic collapse assessment of rigid wall flexible Diaphragm structures
Tenth U.S. National Conference on Earthquake Engineering: Anchorage AK, 2014Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:This study focuses on the development of a two dimensional (2D) simplified numerical framework of rigid wall-flexible Diaphragm (RWFD) structures that can be used to validate seismic design approaches. This type of low-rise industrial buildings, which is widely used in North America, incorporates rigid inplane concrete or masonry walls and flexible in-plane wood, steel or “hybrid” roof Diaphragms. The numerical modeling is detailed enough to capture the nonlinear seismic response of RWFD buildings, but simplified enough to efficiently conduct a large number of nonlinear time-history dynamic analyses. The 2D numerical modeling framework is based on a three step sub-structuring approach including: (1) a hysteretic response database for Diaphragm connectors, (2) a 2D inelastic roof Diaphragm model incorporating hysteretic connector response and (3) a simplified 2D building model incorporating hysteretic Diaphragm model response. The Diaphragm connector database (step 1) was developed for both wood and steel deck connectors using cyclic test data available in the literature. Two well-known hysteretic models (Wayne-Stewart and CUREE-SAWS) were used for estimating/fitting hysteretic parameters of each connector type. The analytical model of the inelastic roof Diaphragm (step 2) was generated to account for the elastic shear deformation of deck panels, elastic flexural deformations of chord members as well as inelastic deformations of deck-to-frame connectors (from the connector database-step 1). This model includes monotonic and cyclic analysis capabilities. The last step of the proposed analytical framework is a simplified two dimensional model of a RWFD building developed in RUAUMOKO2D to account for the inelastic response of roof Diaphragms (based on the analytical roof Diaphragm model-step 2) and the out-of-plane walls as well as second order (P-Δ) effects. Both the proposed analytical model of the roof Diaphragm and the proposed simplified building model were validated with experimental and analytical studies available in the literature. Furthermore, a sensitivity study was conducted to examine the effect of: (i) analysis time step, (ii) different base fixity of the out-of plane walls, (iii) P-Δ effects, (iv) inherent viscous damping and (v) direction of shaking on the collapse assessment of RWFD structures.
Maria Koliou - One of the best experts on this subject based on the ideXlab platform.
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Development of wood and steel Diaphragm hysteretic connector database for performance-based earthquake engineering
Bulletin of Earthquake Engineering, 2017Co-Authors: Maria Koliou, Andre FiliatraultAbstract:Performance-based earthquake engineering (PBEE) considers certain metrics to assess the seismic response of buildings, which integrate economic losses into the design process. PBEE requires the development and use of reliable nonlinear response analysis models to simulate the seismic performance of structures through collapse. The structural damage is assessed by evaluating physical damage caused by engineering demand parameters (EDPs), while the nonlinear numerical models are used to conduct dynamic analyses for varying levels of seismic intensity to compute the values of the representative EDPs. Accurate representation of structural members’ stiffness and strength deterioration (hysteretic) parameters plays an important role into simulating dynamic response through collapse. These parameters’ values are usually calibrated to a large number of experimental data. The development of a hysteretic parameter database for wood and steel Diaphragm connectors is presented in this paper. The wood Diaphragm connectors are commonly used in light-frame wood building construction for shear walls or roof Diaphragms. The steel Diaphragm connectors are used for building structures that incorporate steel frame roof Diaphragms. The experimental data were used for quantifying the hysteretic parameters of two well-known nonlinear models considered into structural modeling as well as evaluating their energy dissipation properties. Case studies on the collapse performance assessment of a light-frame wood wall system and a low-rise building incorporating a steel roof system were conducted to demonstrate the usefulness of the Diaphragm connector database.
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distributed yielding concept for improved seismic collapse performance of rigid wall flexible Diaphragm buildings
Journal of Structural Engineering-asce, 2016Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:AbstractRigid wall-flexible Diaphragm (RWFD) buildings are a common type of single-story construction in North America, Europe, and New Zealand that incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof Diaphragms. RWFD buildings have shown poor seismic performance during past earthquake events. In particular, it has been observed that the global seismic response is dominated by the response of the Diaphragm, which is mainly attributed to large in-plane Diaphragm displacements that significantly exceed the displacements of in-plane walls. In this study, the concept of distributed yielding in the flexible Diaphragm by weakening certain intermediate Diaphragm zones is explored as a cost-effective means to improve the seismic collapse capacity of RWFD buildings and mitigate their seismic vulnerability. A two-dimensional numerical framework was developed specifically for analyzing RWFD buildings and was used to evaluate the proposed concept. Results of nonlinea...
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numerical framework for seismic collapse assessment of rigid wall flexible Diaphragm structures
Tenth U.S. National Conference on Earthquake Engineering: Anchorage AK, 2014Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:This study focuses on the development of a two dimensional (2D) simplified numerical framework of rigid wall-flexible Diaphragm (RWFD) structures that can be used to validate seismic design approaches. This type of low-rise industrial buildings, which is widely used in North America, incorporates rigid inplane concrete or masonry walls and flexible in-plane wood, steel or “hybrid” roof Diaphragms. The numerical modeling is detailed enough to capture the nonlinear seismic response of RWFD buildings, but simplified enough to efficiently conduct a large number of nonlinear time-history dynamic analyses. The 2D numerical modeling framework is based on a three step sub-structuring approach including: (1) a hysteretic response database for Diaphragm connectors, (2) a 2D inelastic roof Diaphragm model incorporating hysteretic connector response and (3) a simplified 2D building model incorporating hysteretic Diaphragm model response. The Diaphragm connector database (step 1) was developed for both wood and steel deck connectors using cyclic test data available in the literature. Two well-known hysteretic models (Wayne-Stewart and CUREE-SAWS) were used for estimating/fitting hysteretic parameters of each connector type. The analytical model of the inelastic roof Diaphragm (step 2) was generated to account for the elastic shear deformation of deck panels, elastic flexural deformations of chord members as well as inelastic deformations of deck-to-frame connectors (from the connector database-step 1). This model includes monotonic and cyclic analysis capabilities. The last step of the proposed analytical framework is a simplified two dimensional model of a RWFD building developed in RUAUMOKO2D to account for the inelastic response of roof Diaphragms (based on the analytical roof Diaphragm model-step 2) and the out-of-plane walls as well as second order (P-Δ) effects. Both the proposed analytical model of the roof Diaphragm and the proposed simplified building model were validated with experimental and analytical studies available in the literature. Furthermore, a sensitivity study was conducted to examine the effect of: (i) analysis time step, (ii) different base fixity of the out-of plane walls, (iii) P-Δ effects, (iv) inherent viscous damping and (v) direction of shaking on the collapse assessment of RWFD structures.
Andre Filiatrault - One of the best experts on this subject based on the ideXlab platform.
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Development of wood and steel Diaphragm hysteretic connector database for performance-based earthquake engineering
Bulletin of Earthquake Engineering, 2017Co-Authors: Maria Koliou, Andre FiliatraultAbstract:Performance-based earthquake engineering (PBEE) considers certain metrics to assess the seismic response of buildings, which integrate economic losses into the design process. PBEE requires the development and use of reliable nonlinear response analysis models to simulate the seismic performance of structures through collapse. The structural damage is assessed by evaluating physical damage caused by engineering demand parameters (EDPs), while the nonlinear numerical models are used to conduct dynamic analyses for varying levels of seismic intensity to compute the values of the representative EDPs. Accurate representation of structural members’ stiffness and strength deterioration (hysteretic) parameters plays an important role into simulating dynamic response through collapse. These parameters’ values are usually calibrated to a large number of experimental data. The development of a hysteretic parameter database for wood and steel Diaphragm connectors is presented in this paper. The wood Diaphragm connectors are commonly used in light-frame wood building construction for shear walls or roof Diaphragms. The steel Diaphragm connectors are used for building structures that incorporate steel frame roof Diaphragms. The experimental data were used for quantifying the hysteretic parameters of two well-known nonlinear models considered into structural modeling as well as evaluating their energy dissipation properties. Case studies on the collapse performance assessment of a light-frame wood wall system and a low-rise building incorporating a steel roof system were conducted to demonstrate the usefulness of the Diaphragm connector database.
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distributed yielding concept for improved seismic collapse performance of rigid wall flexible Diaphragm buildings
Journal of Structural Engineering-asce, 2016Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:AbstractRigid wall-flexible Diaphragm (RWFD) buildings are a common type of single-story construction in North America, Europe, and New Zealand that incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof Diaphragms. RWFD buildings have shown poor seismic performance during past earthquake events. In particular, it has been observed that the global seismic response is dominated by the response of the Diaphragm, which is mainly attributed to large in-plane Diaphragm displacements that significantly exceed the displacements of in-plane walls. In this study, the concept of distributed yielding in the flexible Diaphragm by weakening certain intermediate Diaphragm zones is explored as a cost-effective means to improve the seismic collapse capacity of RWFD buildings and mitigate their seismic vulnerability. A two-dimensional numerical framework was developed specifically for analyzing RWFD buildings and was used to evaluate the proposed concept. Results of nonlinea...
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numerical framework for seismic collapse assessment of rigid wall flexible Diaphragm structures
Tenth U.S. National Conference on Earthquake Engineering: Anchorage AK, 2014Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:This study focuses on the development of a two dimensional (2D) simplified numerical framework of rigid wall-flexible Diaphragm (RWFD) structures that can be used to validate seismic design approaches. This type of low-rise industrial buildings, which is widely used in North America, incorporates rigid inplane concrete or masonry walls and flexible in-plane wood, steel or “hybrid” roof Diaphragms. The numerical modeling is detailed enough to capture the nonlinear seismic response of RWFD buildings, but simplified enough to efficiently conduct a large number of nonlinear time-history dynamic analyses. The 2D numerical modeling framework is based on a three step sub-structuring approach including: (1) a hysteretic response database for Diaphragm connectors, (2) a 2D inelastic roof Diaphragm model incorporating hysteretic connector response and (3) a simplified 2D building model incorporating hysteretic Diaphragm model response. The Diaphragm connector database (step 1) was developed for both wood and steel deck connectors using cyclic test data available in the literature. Two well-known hysteretic models (Wayne-Stewart and CUREE-SAWS) were used for estimating/fitting hysteretic parameters of each connector type. The analytical model of the inelastic roof Diaphragm (step 2) was generated to account for the elastic shear deformation of deck panels, elastic flexural deformations of chord members as well as inelastic deformations of deck-to-frame connectors (from the connector database-step 1). This model includes monotonic and cyclic analysis capabilities. The last step of the proposed analytical framework is a simplified two dimensional model of a RWFD building developed in RUAUMOKO2D to account for the inelastic response of roof Diaphragms (based on the analytical roof Diaphragm model-step 2) and the out-of-plane walls as well as second order (P-Δ) effects. Both the proposed analytical model of the roof Diaphragm and the proposed simplified building model were validated with experimental and analytical studies available in the literature. Furthermore, a sensitivity study was conducted to examine the effect of: (i) analysis time step, (ii) different base fixity of the out-of plane walls, (iii) P-Δ effects, (iv) inherent viscous damping and (v) direction of shaking on the collapse assessment of RWFD structures.
Dominic J Kelly - One of the best experts on this subject based on the ideXlab platform.
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distributed yielding concept for improved seismic collapse performance of rigid wall flexible Diaphragm buildings
Journal of Structural Engineering-asce, 2016Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:AbstractRigid wall-flexible Diaphragm (RWFD) buildings are a common type of single-story construction in North America, Europe, and New Zealand that incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof Diaphragms. RWFD buildings have shown poor seismic performance during past earthquake events. In particular, it has been observed that the global seismic response is dominated by the response of the Diaphragm, which is mainly attributed to large in-plane Diaphragm displacements that significantly exceed the displacements of in-plane walls. In this study, the concept of distributed yielding in the flexible Diaphragm by weakening certain intermediate Diaphragm zones is explored as a cost-effective means to improve the seismic collapse capacity of RWFD buildings and mitigate their seismic vulnerability. A two-dimensional numerical framework was developed specifically for analyzing RWFD buildings and was used to evaluate the proposed concept. Results of nonlinea...
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numerical framework for seismic collapse assessment of rigid wall flexible Diaphragm structures
Tenth U.S. National Conference on Earthquake Engineering: Anchorage AK, 2014Co-Authors: Maria Koliou, Dominic J Kelly, Andre Filiatrault, John W. LawsonAbstract:This study focuses on the development of a two dimensional (2D) simplified numerical framework of rigid wall-flexible Diaphragm (RWFD) structures that can be used to validate seismic design approaches. This type of low-rise industrial buildings, which is widely used in North America, incorporates rigid inplane concrete or masonry walls and flexible in-plane wood, steel or “hybrid” roof Diaphragms. The numerical modeling is detailed enough to capture the nonlinear seismic response of RWFD buildings, but simplified enough to efficiently conduct a large number of nonlinear time-history dynamic analyses. The 2D numerical modeling framework is based on a three step sub-structuring approach including: (1) a hysteretic response database for Diaphragm connectors, (2) a 2D inelastic roof Diaphragm model incorporating hysteretic connector response and (3) a simplified 2D building model incorporating hysteretic Diaphragm model response. The Diaphragm connector database (step 1) was developed for both wood and steel deck connectors using cyclic test data available in the literature. Two well-known hysteretic models (Wayne-Stewart and CUREE-SAWS) were used for estimating/fitting hysteretic parameters of each connector type. The analytical model of the inelastic roof Diaphragm (step 2) was generated to account for the elastic shear deformation of deck panels, elastic flexural deformations of chord members as well as inelastic deformations of deck-to-frame connectors (from the connector database-step 1). This model includes monotonic and cyclic analysis capabilities. The last step of the proposed analytical framework is a simplified two dimensional model of a RWFD building developed in RUAUMOKO2D to account for the inelastic response of roof Diaphragms (based on the analytical roof Diaphragm model-step 2) and the out-of-plane walls as well as second order (P-Δ) effects. Both the proposed analytical model of the roof Diaphragm and the proposed simplified building model were validated with experimental and analytical studies available in the literature. Furthermore, a sensitivity study was conducted to examine the effect of: (i) analysis time step, (ii) different base fixity of the out-of plane walls, (iii) P-Δ effects, (iv) inherent viscous damping and (v) direction of shaking on the collapse assessment of RWFD structures.
Neal A Rubinstein - One of the best experts on this subject based on the ideXlab platform.
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rapid disuse atrophy of Diaphragm fibers in mechanically ventilated humans
The New England Journal of Medicine, 2008Co-Authors: Sanford Levine, Taitan Nguyen, Nyali E Taylor, Michael E Friscia, Murat T Budak, Pamela Rothenberg, Rajeev Sachdeva, Seema S Sonnad, Larry R Kaiser, Neal A RubinsteinAbstract:Background The combination of complete Diaphragm inactivity and mechanical ventilation (for more than 18 hours) elicits disuse atrophy of myofibers in animals. We hypothesized that the same may also occur in the human Diaphragm. Methods We obtained biopsy specimens from the costal Diaphragms of 14 brain-dead organ donors before organ harvest (case subjects) and compared them with intraoperative biopsy specimens from the Diaphragms of 8 patients who were undergoing surgery for either benign lesions or localized lung cancer (control subjects). Case subjects had Diaphragmatic inactivity and underwent mechanical ventilation for 18 to 69 hours; among control subjects Diaphragmatic inactivity and mechanical ventilation were limited to 2 to 3 hours. We carried out histologic, biochemical, and gene-expression studies on these specimens. Results As compared with Diaphragm-biopsy specimens from controls, specimens from case subjects showed decreased cross-sectional areas of slow-twitch and fast-twitch fibers of 57% (P = 0.001) and 53% (P = 0.01), respectively, decreased glutathione concentration of 23% (P = 0.01), increased active caspase-3 expression of 100% (P = 0.05), a 200% higher ratio of atrogin-1 messenger RNA (mRNA) transcripts to MBD4 (a housekeeping gene) (P = 0.002), and a 590% higher ratio of MuRF-1 mRNA transcripts to MBD4 (P = 0.001). Conclusions The combination of 18 to 69 hours of complete Diaphragmatic inactivity and mechanical ventilation results in marked atrophy of human Diaphragm myofibers. These findings are consistent with increased Diaphragmatic proteolysis during inactivity.