Since its introduction in Europe more than two decades ago, Cross Laminated Timber (CLT) is viewe... more Since its introduction in Europe more than two decades ago, Cross Laminated Timber (CLT) is viewed as a newgeneration of engineered wood products and has found its way into the US construction market. Recent research efforts have demonstrated that CLT can be effectively utilized as a seismic force resisting system. This paper presents the results of part of a study conducted at Colorado State University to systematically investigate seismic behaviour of CLT shear wall systems in regions of high seismicity for use in the United States. Specifically, the results of a full-scale shake table test of a two-storey 223 m building. The CLT special shear walls in the building were designed based on a design methodology that resulted from connector and reverse cyclic testing of isolated CLT shear walls using a generic connector. The main design assumption for these walls is that all overturning was resisted by the overturning anchor (tie-down rod or hold-downs) at the wall ends and the shear ...
In the framework of a third Tagus River crossing, t hrough an immersed tunnel, advanced laborator... more In the framework of a third Tagus River crossing, t hrough an immersed tunnel, advanced laboratory tests were performed on its highly lique fiable foundation sand, namely cyclic undrained torsional tests. The Manzari-Dafalias mod el, which allows simulating liquefaction on the Tagus River sand and is, therefore, central in the tunnel design, as well as the numerical work to calibrate the model and identify ts most relevant parameters, are presented. Model parameters, their respective refer enc values and tests performed to determine directly most of the parameters, are intr oduced. A parameter sensitivity analysis, conducted through numerical simulation of triaxial monotonic drained tests and of cyclic undrained torsional tests, implemented both for the pre-liquefaction and liquefaction phases, is described. Finally, some parameters are determin d by fitting the model to the laboratory results.
In North America, tall wood building design and construction is still inhibited by a lack of prec... more In North America, tall wood building design and construction is still inhibited by a lack of precedents and coherent incorporation of design standards into the building code. For this reason, it needs to be demonstrated that mass timber products – such as cross-laminated timber (CLT) – and new tall wood buildings can meet or exceed existing performance standards as specified for concrete and steel. Currently, for tall wood buildings, this is generally accomplished through extensive testing, engineering analysis, and a stringent peer review process. This paper presents the scope and preliminary outcomes of the “SMART-CLT” project, conducted through the Oregon State University College of Forestry’s Institute for Working Forest Landscapes (IWFL). This project aims to cross reference laboratory research and in-situ monitoring to establish a holistic performancemonitoring protocol for mass timber buildings; this protocol can later serve to define standards for midto long-term monitoring ...
Investigating structures damaged by strong earthquakes can provide valuable insight in understand... more Investigating structures damaged by strong earthquakes can provide valuable insight in understanding the performance of structures during such events. Few studies have been conducted on structures using post-earthquake vibration data to assess their state of health/performance. This paper presents such a study by considering an 18-story apartment building damaged during the 7.8 Gorkha Earthquake that occurred in Nepal in April 25, 2015. The building was instrumented with 15 accelerometers in two configurations that measured its ambient vibration response. The recorded data is analyzed and the modal parameters of the test structure are identified using the Natural Excitation Technique combined with Eigensystem Realization Algorithm (NExT-ERA), an output-only system identification method. Moreover, a newly developed simplified analytical tool is used to simulate the response of the structure. This tool allows the estimation of the base shear-vs.displacement curve for the structure in ...
In this paper, the numerical work that has been don e t calibrate the Manzari-Dafalias model and ... more In this paper, the numerical work that has been don e t calibrate the Manzari-Dafalias model and to id entify its more relevant parameters is presented. The model paramet ers, their respective reference values and the test s that were performed to determine most of the parameters are i nt oduced. A parameter sensitivity analysis through numerical simulation of a triaxial monotonic drained test, us ing an OpenSees model with a single 1x1x1 m 3 SSPbrickUP 3D element, is described and the results analyzed. The sensitivity analysis is conducted for each paramet er individually, for several pairs of physically related parameters and of the most relevant ones. It is considered the fin al i fluence upon the peak values of the shear strain , shear stress ratio and dilatancy and upon the critical state volumetr ic strain . Furthermore, a parameter sensitivity analysis throu gh numerical simulation of a cyclic undrained torsi nal test is implemented, both for the pre-liquefaction and liqu efa...
The April 2015 M7.8 Gorkha Earthquake and its aftershocks caused extensive damage to numerous cul... more The April 2015 M7.8 Gorkha Earthquake and its aftershocks caused extensive damage to numerous cultural heritage sites throughout Nepal. While many structures experienced complete collapses, one of the most recognizable cultural heritage sites that suffered damage was the five-tiered Nyatapola Temple, a UNESCO World Heritage site located in Bhaktapur, Nepal. This temple was originally completed in 1702 and survived both the 1934 Nepal-Bihar and 2015 Gorkha Earthquake and subsequent aftershocks. However, this historical temple experienced extensive cracks within the unreinforced masonry brick walls with mud-mortar during the 2015 earthquake. As a result, the authors collected detailed assessment data to characterize its state in the aftermath of the 2015 earthquake to inform potential rehabilitation solutions. The data collected includes ambient vibration data and ground-based lidar. The ambient vibration data was collected via accelerometers placed each roof level in three different ...
This paper proposes a probabilistic seismic fragility analysis framework for building structures ... more This paper proposes a probabilistic seismic fragility analysis framework for building structures that explicitly incorporates the cascading impact of mainshock-triggered aftershock earthquake events. The effect of aftershocks is considered by proposing a methodology for generating seismic hazard-consistent mainshock-aftershock sequences for different levels of hazard intensity. This methodology integrates probabilistic seismic hazard deaggregation analysis, empirical seismological models and stochastic ground motion modeling. Application of the proposed framework to a characteristic steel moment resisting frame building in California allows for the evaluation of mainshock-induced damage state-dependent aftershock fragilities and comparison with classic mainshock only fragilities. This comparison highlights the importance of incorporating aftershock seismic events in the seismic hazard characterization, since it is shown that the structure is significantly more vulnerable when it is ...
Unreinforced masonry (URM) infill walls are widely used in regions with high seismicity around th... more Unreinforced masonry (URM) infill walls are widely used in regions with high seismicity around the world. When subjected to seismic loading, the failure of these walls is often catastrophic as these walls typically exhibit brittle failures. These catastrophic failures have been observed since earthquakes in the 1930s and also in the aftermath of recent earthquakes such as the 2010 Haiti (Mw 7.0), the 2010 Maule Chile (Mw 8.8), and the 2010 and 2011 Darfield and Christchurch New Zealand earthquakes (Mw 7.1 and Mw 6.3, respectively). All the failures observed should be reason enough for retrofitting of URM and URM infill RC frames, but the cost is typically the main hindrance to seismically upgrading these URM walls. Thus, there still is a pressing need for developing cost-effective retrofit strategies. A simple and cost-effective retrofit solution for URM infill walls is proposed herein, in which embedded reinforcing steel bars are placed in pre-cut grooves made on the surface of the...
Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made of at least th... more Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made of at least three orthogonally bonded layers of solid-sawn lumber that are laminated by gluing longitudinal and transverse layers with structural adhesives to form a solid panel. Previous studies have shown that the CLT buildings can perform well in seismic loading and are recognized as the essential role of connector performance in structural design, modelling, and analysis of CLT buildings. When CLT is composed of high-grade/high-density layers for the outer lamellas and low-grade/low-density for the core of the panels, the CLT panels are herein designated as hybrid CLT panels as opposed to conventional CLT panels that are built using one lumber type for both outer and core lamellas. This paper presents results of a testing program developed to estimate the cyclic performance of CLT connectors applied on hybrid CLT layups. Two connectors are selected, which can be used in wall-to-floor connections. ...
S . M i s r a 1, J . E . P a d g e t t 2 , A . R . B a r b o s a 3 , B . M . We b b 4 1 G r a d u... more S . M i s r a 1, J . E . P a d g e t t 2 , A . R . B a r b o s a 3 , B . M . We b b 4 1 G r a d u a t e R e s e a r c h A s s i s t a n t , D e p t . o f C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , R i c e U n i v e r s i t y 2 A s s o c i a t e P r o f e s s o r, D e p t . o f C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , R i c e U n i v e r s i t y 3 A s s i s t a n t P r o f e s s o r, S c h o o l o f C i v i l a n d C o n s t r u c t i o n E n g i n e e r i n g , O r e g o n S t a t e U n i v e r s i t y 4 P r o f e s s o r, C i v i l , C o a s t a l a n d E n v i r o n m e n t a l E n g i n e e r i n g , U n i v e r s i t y o f S o u t h A l a b a m a
Mass timber construction has been gaining momentum in multi-story residential and commercial cons... more Mass timber construction has been gaining momentum in multi-story residential and commercial construction sectors in North America. As taller mass timber buildings are being planned and constructed, in-situ dynamic tests of this type of construction can be performed to further validate their design and use. As part of this larger effort, an in-situ dynamic characterization testing campaign based on ambient vibration measurements was conducted on a recently constructed four-story mass timber building located in Portland, Oregon. The building features cross-laminated timber (CLT) floors, a glued laminated timber (GLT) framing gravity system, and light-frame shear walls and steel HSS hold-downs that compose the lateral resisting system of the building. Ambient vibration acceleration testing data were collected using 18 accelerometers that were wired to a portable data acquisition system in two experimental setups. Approximately 2 h of bi-directional horizontal acceleration data were recorded. In this paper, two operational modal analysis methods are used for estimating the modal parameters (frequency, damping, and mode shapes) based on the data collected. In addition, a multi-stage linear Finite Element (FE) model updating procedure is presented for this building type and the FE estimates of frequencies and mode shapes are compared to estimates from the collected data. The calibrated FE model provides confidence to the operational modal results and presents a comprehensive modal characterization of the building. At ambient levels of excitation, the developed FE model suggests that stiffness of the non-structural elements, such as the exterior wall cladding, and glazing affects the modal response of the building considerably. Lessons learnt on this unique and first of a kind four-story structure constructed in the United States and implications for taller mass timber buildings are summarized and provide valuable insight for the design and assessment for this building type under future dynamic excitation events.
A broad range of building performance monitoring, sampling, and evaluation was conducted periodic... more A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of ...
A broad range of building performance monitoring, sampling, and evaluation was conducted periodic... more A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of ...
Finite-length plastic hinge (FLPH) models have shown advantages over the concentrated plasticity ... more Finite-length plastic hinge (FLPH) models have shown advantages over the concentrated plasticity hinge (CPH) models. However, empirical phenomenological relationships, such as Modified Ibarra-Medina-Krawinkler (ModIMK) deterioration model, were mainly calibrated for use in CPH models. ModIMK relationships are versatile and have been applied to steel, reinforced concrete, and timber structures. Herein, a calibration procedure of FLPH models and a unified algorithm for use of ModIMK relationships in CPH and FLPH models are presented. Results from included examples validate the proposed algorithms, which were implemented in OpenSees. Additionally, results highlight that FPLH models avoid errors and convergence pitfalls of CPH models.
Post-disaster, rapid response research reconnaissance is one of the most powerful means to unders... more Post-disaster, rapid response research reconnaissance is one of the most powerful means to understand the effects of natural hazards on the nation's built environment. The structural engineering community's ability to advance windstorm design and construction methodologies is greatly informed by systematically documenting the performance of residential homes, buildings, and other civil infrastructure under actual hazard conditions. The 2017 hurricane season has been an especially unprecedented venue for such investigations. The season included Hurricane Irma, the most powerful Atlantic Hurricane on record, sustaining 185-mph winds and Category 5 status longer than any prior storm. Irma left a path of considerable destruction across the Caribbean. The U.S. Virgin Islands and Puerto Rico were exposed to Irma's full Category 5 strength, claiming three lives and compromising basic infrastructure in Puerto Rico, while delivering staggering damage to the U.S. Virgin Islands.
Coastal communities provide important economic, transport, and recreational services to large num... more Coastal communities provide important economic, transport, and recreational services to large numbers of people worldwide. However, these coastal communities are vulnerable to damage by extreme events such as tropical cyclones or tsunamis. Waves and surge, as well as tsunami-wave events, may cause extensive damage to elevated structures through a combination of horizontal and vertical wave and surge-induced forces. Structural elevation has been shown to be a critical variable affecting damage and loss. Recent efforts have been made to retrofit structures or improve coastal protection and damage mitigation plans in coastal communities to increase community resilience. However, to effectively retrofit old structures or design new structures to resist damage due to hurricanes or tsunamis, engineers require an accurate estimation of both the wave hydrodynamics and the resulting loads.
Cross-laminated timber (CLT) manufacturing and construction has been steadily growing since its i... more Cross-laminated timber (CLT) manufacturing and construction has been steadily growing since its inception in Europe in the 1990s. In the US, the growth of the CLT adoption is inhibited by the lack of codified design provisions for CLT in high seismic regions. This led to a multi-year study conducted by Colorado State University to investigate suitable seismic design parameters of CLT shear wall systems. This paper presents the results from a series of shake-table tests featuring a full-scale two-story mass-timber building utilizing CLT Seismic Force Resisting Systems (SFRS). The building was designed using an R-factor equal to 4.0 under the equivalent lateral force procedure specifications of the ASCE 7-16 Standard. The test program included three phases with different wall configurations, reflecting different wall panel aspect ratios and the existence of transverse CLT walls. Test results indicate that the code-level life safety objective was achieved in all test configurations. The addition of transverse walls did not affect the ability of the panels to rock, and improved the performance of the building structural system.
Since its introduction in Europe more than two decades ago, Cross Laminated Timber (CLT) is viewe... more Since its introduction in Europe more than two decades ago, Cross Laminated Timber (CLT) is viewed as a newgeneration of engineered wood products and has found its way into the US construction market. Recent research efforts have demonstrated that CLT can be effectively utilized as a seismic force resisting system. This paper presents the results of part of a study conducted at Colorado State University to systematically investigate seismic behaviour of CLT shear wall systems in regions of high seismicity for use in the United States. Specifically, the results of a full-scale shake table test of a two-storey 223 m building. The CLT special shear walls in the building were designed based on a design methodology that resulted from connector and reverse cyclic testing of isolated CLT shear walls using a generic connector. The main design assumption for these walls is that all overturning was resisted by the overturning anchor (tie-down rod or hold-downs) at the wall ends and the shear ...
In the framework of a third Tagus River crossing, t hrough an immersed tunnel, advanced laborator... more In the framework of a third Tagus River crossing, t hrough an immersed tunnel, advanced laboratory tests were performed on its highly lique fiable foundation sand, namely cyclic undrained torsional tests. The Manzari-Dafalias mod el, which allows simulating liquefaction on the Tagus River sand and is, therefore, central in the tunnel design, as well as the numerical work to calibrate the model and identify ts most relevant parameters, are presented. Model parameters, their respective refer enc values and tests performed to determine directly most of the parameters, are intr oduced. A parameter sensitivity analysis, conducted through numerical simulation of triaxial monotonic drained tests and of cyclic undrained torsional tests, implemented both for the pre-liquefaction and liquefaction phases, is described. Finally, some parameters are determin d by fitting the model to the laboratory results.
In North America, tall wood building design and construction is still inhibited by a lack of prec... more In North America, tall wood building design and construction is still inhibited by a lack of precedents and coherent incorporation of design standards into the building code. For this reason, it needs to be demonstrated that mass timber products – such as cross-laminated timber (CLT) – and new tall wood buildings can meet or exceed existing performance standards as specified for concrete and steel. Currently, for tall wood buildings, this is generally accomplished through extensive testing, engineering analysis, and a stringent peer review process. This paper presents the scope and preliminary outcomes of the “SMART-CLT” project, conducted through the Oregon State University College of Forestry’s Institute for Working Forest Landscapes (IWFL). This project aims to cross reference laboratory research and in-situ monitoring to establish a holistic performancemonitoring protocol for mass timber buildings; this protocol can later serve to define standards for midto long-term monitoring ...
Investigating structures damaged by strong earthquakes can provide valuable insight in understand... more Investigating structures damaged by strong earthquakes can provide valuable insight in understanding the performance of structures during such events. Few studies have been conducted on structures using post-earthquake vibration data to assess their state of health/performance. This paper presents such a study by considering an 18-story apartment building damaged during the 7.8 Gorkha Earthquake that occurred in Nepal in April 25, 2015. The building was instrumented with 15 accelerometers in two configurations that measured its ambient vibration response. The recorded data is analyzed and the modal parameters of the test structure are identified using the Natural Excitation Technique combined with Eigensystem Realization Algorithm (NExT-ERA), an output-only system identification method. Moreover, a newly developed simplified analytical tool is used to simulate the response of the structure. This tool allows the estimation of the base shear-vs.displacement curve for the structure in ...
In this paper, the numerical work that has been don e t calibrate the Manzari-Dafalias model and ... more In this paper, the numerical work that has been don e t calibrate the Manzari-Dafalias model and to id entify its more relevant parameters is presented. The model paramet ers, their respective reference values and the test s that were performed to determine most of the parameters are i nt oduced. A parameter sensitivity analysis through numerical simulation of a triaxial monotonic drained test, us ing an OpenSees model with a single 1x1x1 m 3 SSPbrickUP 3D element, is described and the results analyzed. The sensitivity analysis is conducted for each paramet er individually, for several pairs of physically related parameters and of the most relevant ones. It is considered the fin al i fluence upon the peak values of the shear strain , shear stress ratio and dilatancy and upon the critical state volumetr ic strain . Furthermore, a parameter sensitivity analysis throu gh numerical simulation of a cyclic undrained torsi nal test is implemented, both for the pre-liquefaction and liqu efa...
The April 2015 M7.8 Gorkha Earthquake and its aftershocks caused extensive damage to numerous cul... more The April 2015 M7.8 Gorkha Earthquake and its aftershocks caused extensive damage to numerous cultural heritage sites throughout Nepal. While many structures experienced complete collapses, one of the most recognizable cultural heritage sites that suffered damage was the five-tiered Nyatapola Temple, a UNESCO World Heritage site located in Bhaktapur, Nepal. This temple was originally completed in 1702 and survived both the 1934 Nepal-Bihar and 2015 Gorkha Earthquake and subsequent aftershocks. However, this historical temple experienced extensive cracks within the unreinforced masonry brick walls with mud-mortar during the 2015 earthquake. As a result, the authors collected detailed assessment data to characterize its state in the aftermath of the 2015 earthquake to inform potential rehabilitation solutions. The data collected includes ambient vibration data and ground-based lidar. The ambient vibration data was collected via accelerometers placed each roof level in three different ...
This paper proposes a probabilistic seismic fragility analysis framework for building structures ... more This paper proposes a probabilistic seismic fragility analysis framework for building structures that explicitly incorporates the cascading impact of mainshock-triggered aftershock earthquake events. The effect of aftershocks is considered by proposing a methodology for generating seismic hazard-consistent mainshock-aftershock sequences for different levels of hazard intensity. This methodology integrates probabilistic seismic hazard deaggregation analysis, empirical seismological models and stochastic ground motion modeling. Application of the proposed framework to a characteristic steel moment resisting frame building in California allows for the evaluation of mainshock-induced damage state-dependent aftershock fragilities and comparison with classic mainshock only fragilities. This comparison highlights the importance of incorporating aftershock seismic events in the seismic hazard characterization, since it is shown that the structure is significantly more vulnerable when it is ...
Unreinforced masonry (URM) infill walls are widely used in regions with high seismicity around th... more Unreinforced masonry (URM) infill walls are widely used in regions with high seismicity around the world. When subjected to seismic loading, the failure of these walls is often catastrophic as these walls typically exhibit brittle failures. These catastrophic failures have been observed since earthquakes in the 1930s and also in the aftermath of recent earthquakes such as the 2010 Haiti (Mw 7.0), the 2010 Maule Chile (Mw 8.8), and the 2010 and 2011 Darfield and Christchurch New Zealand earthquakes (Mw 7.1 and Mw 6.3, respectively). All the failures observed should be reason enough for retrofitting of URM and URM infill RC frames, but the cost is typically the main hindrance to seismically upgrading these URM walls. Thus, there still is a pressing need for developing cost-effective retrofit strategies. A simple and cost-effective retrofit solution for URM infill walls is proposed herein, in which embedded reinforcing steel bars are placed in pre-cut grooves made on the surface of the...
Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made of at least th... more Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made of at least three orthogonally bonded layers of solid-sawn lumber that are laminated by gluing longitudinal and transverse layers with structural adhesives to form a solid panel. Previous studies have shown that the CLT buildings can perform well in seismic loading and are recognized as the essential role of connector performance in structural design, modelling, and analysis of CLT buildings. When CLT is composed of high-grade/high-density layers for the outer lamellas and low-grade/low-density for the core of the panels, the CLT panels are herein designated as hybrid CLT panels as opposed to conventional CLT panels that are built using one lumber type for both outer and core lamellas. This paper presents results of a testing program developed to estimate the cyclic performance of CLT connectors applied on hybrid CLT layups. Two connectors are selected, which can be used in wall-to-floor connections. ...
S . M i s r a 1, J . E . P a d g e t t 2 , A . R . B a r b o s a 3 , B . M . We b b 4 1 G r a d u... more S . M i s r a 1, J . E . P a d g e t t 2 , A . R . B a r b o s a 3 , B . M . We b b 4 1 G r a d u a t e R e s e a r c h A s s i s t a n t , D e p t . o f C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , R i c e U n i v e r s i t y 2 A s s o c i a t e P r o f e s s o r, D e p t . o f C i v i l a n d E n v i r o n m e n t a l E n g i n e e r i n g , R i c e U n i v e r s i t y 3 A s s i s t a n t P r o f e s s o r, S c h o o l o f C i v i l a n d C o n s t r u c t i o n E n g i n e e r i n g , O r e g o n S t a t e U n i v e r s i t y 4 P r o f e s s o r, C i v i l , C o a s t a l a n d E n v i r o n m e n t a l E n g i n e e r i n g , U n i v e r s i t y o f S o u t h A l a b a m a
Mass timber construction has been gaining momentum in multi-story residential and commercial cons... more Mass timber construction has been gaining momentum in multi-story residential and commercial construction sectors in North America. As taller mass timber buildings are being planned and constructed, in-situ dynamic tests of this type of construction can be performed to further validate their design and use. As part of this larger effort, an in-situ dynamic characterization testing campaign based on ambient vibration measurements was conducted on a recently constructed four-story mass timber building located in Portland, Oregon. The building features cross-laminated timber (CLT) floors, a glued laminated timber (GLT) framing gravity system, and light-frame shear walls and steel HSS hold-downs that compose the lateral resisting system of the building. Ambient vibration acceleration testing data were collected using 18 accelerometers that were wired to a portable data acquisition system in two experimental setups. Approximately 2 h of bi-directional horizontal acceleration data were recorded. In this paper, two operational modal analysis methods are used for estimating the modal parameters (frequency, damping, and mode shapes) based on the data collected. In addition, a multi-stage linear Finite Element (FE) model updating procedure is presented for this building type and the FE estimates of frequencies and mode shapes are compared to estimates from the collected data. The calibrated FE model provides confidence to the operational modal results and presents a comprehensive modal characterization of the building. At ambient levels of excitation, the developed FE model suggests that stiffness of the non-structural elements, such as the exterior wall cladding, and glazing affects the modal response of the building considerably. Lessons learnt on this unique and first of a kind four-story structure constructed in the United States and implications for taller mass timber buildings are summarized and provide valuable insight for the design and assessment for this building type under future dynamic excitation events.
A broad range of building performance monitoring, sampling, and evaluation was conducted periodic... more A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of ...
A broad range of building performance monitoring, sampling, and evaluation was conducted periodic... more A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of ...
Finite-length plastic hinge (FLPH) models have shown advantages over the concentrated plasticity ... more Finite-length plastic hinge (FLPH) models have shown advantages over the concentrated plasticity hinge (CPH) models. However, empirical phenomenological relationships, such as Modified Ibarra-Medina-Krawinkler (ModIMK) deterioration model, were mainly calibrated for use in CPH models. ModIMK relationships are versatile and have been applied to steel, reinforced concrete, and timber structures. Herein, a calibration procedure of FLPH models and a unified algorithm for use of ModIMK relationships in CPH and FLPH models are presented. Results from included examples validate the proposed algorithms, which were implemented in OpenSees. Additionally, results highlight that FPLH models avoid errors and convergence pitfalls of CPH models.
Post-disaster, rapid response research reconnaissance is one of the most powerful means to unders... more Post-disaster, rapid response research reconnaissance is one of the most powerful means to understand the effects of natural hazards on the nation's built environment. The structural engineering community's ability to advance windstorm design and construction methodologies is greatly informed by systematically documenting the performance of residential homes, buildings, and other civil infrastructure under actual hazard conditions. The 2017 hurricane season has been an especially unprecedented venue for such investigations. The season included Hurricane Irma, the most powerful Atlantic Hurricane on record, sustaining 185-mph winds and Category 5 status longer than any prior storm. Irma left a path of considerable destruction across the Caribbean. The U.S. Virgin Islands and Puerto Rico were exposed to Irma's full Category 5 strength, claiming three lives and compromising basic infrastructure in Puerto Rico, while delivering staggering damage to the U.S. Virgin Islands.
Coastal communities provide important economic, transport, and recreational services to large num... more Coastal communities provide important economic, transport, and recreational services to large numbers of people worldwide. However, these coastal communities are vulnerable to damage by extreme events such as tropical cyclones or tsunamis. Waves and surge, as well as tsunami-wave events, may cause extensive damage to elevated structures through a combination of horizontal and vertical wave and surge-induced forces. Structural elevation has been shown to be a critical variable affecting damage and loss. Recent efforts have been made to retrofit structures or improve coastal protection and damage mitigation plans in coastal communities to increase community resilience. However, to effectively retrofit old structures or design new structures to resist damage due to hurricanes or tsunamis, engineers require an accurate estimation of both the wave hydrodynamics and the resulting loads.
Cross-laminated timber (CLT) manufacturing and construction has been steadily growing since its i... more Cross-laminated timber (CLT) manufacturing and construction has been steadily growing since its inception in Europe in the 1990s. In the US, the growth of the CLT adoption is inhibited by the lack of codified design provisions for CLT in high seismic regions. This led to a multi-year study conducted by Colorado State University to investigate suitable seismic design parameters of CLT shear wall systems. This paper presents the results from a series of shake-table tests featuring a full-scale two-story mass-timber building utilizing CLT Seismic Force Resisting Systems (SFRS). The building was designed using an R-factor equal to 4.0 under the equivalent lateral force procedure specifications of the ASCE 7-16 Standard. The test program included three phases with different wall configurations, reflecting different wall panel aspect ratios and the existence of transverse CLT walls. Test results indicate that the code-level life safety objective was achieved in all test configurations. The addition of transverse walls did not affect the ability of the panels to rock, and improved the performance of the building structural system.
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Papers by Andre Barbosa