Technical Guide for Evaluation of Seismic Force Resisting Systems and Their Force Modification Factors for Use in the National Building Code of Canada with Concepts Illustrated Using a Cantilevered Wood CLT Shear Wall Example
The objective of this guideline is to provide a simple, systematic, and sufficient procedure for evaluating the performance of Seismic Force Resisting Systems (SFRSs) and to determine the appropriate ductilityrelated (Rd) and over-strength related (Ro) force modification factors for implementation in the National Building Code of Canada (NBC). The procedure relies on the application of non-linear dynamic analysis for quantification of the seismic performance of the SFRS. Note that the procedure is also suitable for assessing force modification factors (RdRo values) of systems already implemented in the NBC.
The audience for this guideline are those (called the “project study team” in this document) who submit proposals for new SFRSs with defined RdRo values to the NBC for inclusion in Subsection 4.1.8., Earthquake Loads and Effects, of Division B of the NBC. This guideline can also be used by a team performing an alternative design solution for a specific project and seeking acceptance from authority having jurisdiction. In such cases, not all aspects of this guideline (e.g., having different archetypes) will be needed.
This project proposes a timber-based composite floor that can span 12 m and be used in the construction of 40+ story office buildings. This floor system integrates timber panels and timber beams to form a continuous box girder structure. The timber panels function as the flanges and the timber beams as the web. The beams are spaced and connected to the flange panels so that sufficient bending stiffness of a 12 m span can be achieved via the development of composite action.
The current phase of this project studied the performance of the connections between timber elements in the proposed composite member. Six types of connections using different flange material and connection techniques were tested: Cross Laminated Timber (CLT), Laminated Strand Lumber (LSL), Laminated Veneer Lumber (LVL), and Post Laminated Veneer Lumber (PLVL). Glulam was used as the web. The majority of the connections used self-tapping wood screws except one had notches. The load-carrying capacity, stiffness, and ductility of the connections were measured. The stiffness of CLT, LSL, and PLVL connections was in the same range, 19-20 kN/mm per screw. Amongst the three, LSL had the highest peak load and PLVL had the highest proportional limit. The stiffness of the two LVL screw connections was around 13 kN/mm. The notched LVL connection had significantly higher stiffness than the rest, and its peak load was in the same range as LSL, but the failure was brittle.
LVL was used to manufacture the full scale timber composite floor element. With a spacing of 400 mm, the overall stiffness reached 33689 N
mm2×109, which was 2.5 times the combined stiffness of two Glulam beams. The predicted overall stiffness based on Gamma method was within 5% of the tested value, and the estimated degree of composite action was 68%. From both the test results and analytical modeling, the number of screws may be further reduced to 50% or less of the current amount, while maintaining a high level of stiffness.
Future work includes testing the composite floor under different screw spacings,
investigating the effect of concrete topping, and the connections between floor members
and other structural elements.
Project contact is Erica Fischer at Oregon State University
This Faculty Early Career Development (CAREER) award will create innovative building technology that will enable mass timber modular construction as a building solution to many of the issues the nation's major cities face today. The architecture, engineering, and construction (AEC) sector is on the cusp of a significant disruption that will change the way buildings are manufactured, assembled, and designed, the catalyst of which is the integration of building information models (BIM) and automated construction and manufacturing. This disruption will significantly impact structural engineers. With the streamlining of building manufacturing, assembling, and design, engineers will need to take advantage of three opportunities: (1) design for constructability, (2) design for manufacturing, and (3) design for the whole life of the building (considering future modifications, maintenance, and easily replacing parts of the building). Modular construction, as one method to take advantage of these three opportunities, can address labor and housing shortages that exist in almost every U.S. city today and also can provide rapid construction methods for post-disaster reconstruction and additional patient care facilities. This research will contribute to the state of Oregon’s economy, which has made significant investments in mass timber production, manufacturing, and research. This research will be complemented through the development of best practices for using interdisciplinary, collaborative classroom environments to enhance engineering identities of underrepresented minorities and women at the graduate level. This award will support the National Science Foundation (NSF) role in the National Earthquake Hazards Reduction Program and the National Windstorm Impact Reduction Program.
The specific goal of this research is to develop a novel framework for robust and ductile mass timber modular construction that can be applied to buildings with varying lateral force resisting systems. Through this framework, the relationship between the rigidity of modular interconnections and overall structural behavior will be investigated. The research objectives of this project are to: (1) quantify the demands in interconnections that provide ductility when the building framing is subjected to combined gravity and lateral forces (seismic and wind); (2) quantify the impact of interconnection configuration and design on the ability of interconnections to meet the strength and serviceability performance criteria for mass timber high-rise modular buildings; (3) quantify ductility and overstrength for mass timber modular construction and explore applicability of conventional seismic performance factors and how these factors influence the adjusted collapse margin ratio for archetype buildings; (4) explore the influence of interconnection stiffness on the behavior of high-rise modular mass timber buildings subjected to wind demands; and (5) explore the relationship between team-focused and interdisciplinary educational practices with engineering identity and knowledge retention. New connection technology will be created and its contribution to the overall building behavior will be investigated through a rigorous testing plan and complex physics-based numerical simulations of archetype buildings subjected to combined gravity and lateral loads (seismic and wind). This research is a critical first step to develop innovative technology that will change how buildings are designed, manufactured, and assembled. This project will enable the Principal Investigator to establish interdisciplinary research, teaching, and mentorship in the area of mass timber and hybrid construction. This research will use the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Boundary Layer Wind Tunnel facility at the University of Florida. Experimental datasets will be archived in the NHERI Data Depot (https://www.DesignSafe-ci.org) and made publicly available.
Project contact is Peter Dusicka at Portland State University
The urgency in increasing growth in densely populated urban areas, reducing the carbon footprint of new buildings, and targeting rapid return to occupancy following disastrous earthquakes has created a need to reexamine the structural systems of mid- to high-rise buildings. To address these sustainability and seismic resiliency needs, the objective of this research is to enable an all-timber material system in a way that will include architectural as well as structural considerations. Utilization of mass timber is societally important in providing buildings that store, instead of generate, carbon and increase the economic opportunity for depressed timber-producing regions of the country. This research will focus on buildings with core walls because those building types are some of the most common for contemporary urban mid- to high-rise construction. The open floor layout will allow for commercial and mixed-use occupancies, but also will contain significant technical knowledge gaps hindering their implementation with mass timber. The research plan has been formulated to fill these gaps by: (1) developing suitable mid- to high-rise archetypes with input from multiple stakeholders, (2) conducting parametric system-level seismic performance investigations, (3) developing new critical components, (4) validating the performance with large-scale experimentation, and (5) bridging the industry information gaps by incorporating teaching modules within an existing educational and outreach framework. Situated in the heart of a timber-producing region, the multi-disciplinary team will utilize the local design professional community with timber experience and Portland State University's recently implemented Green Building Scholars program to deliver technical outcomes that directly impact the surrounding environment.
Research outcomes will advance knowledge at the system performance level as well as at the critical component level. The investigated building system will incorporate cross laminated timber cores, floors, and glulam structural members. Using mass timber will present challenges in effectively achieving the goal of desirable seismic performance, especially seismic resiliency. These challenges will be addressed at the system level by a unique combination of core rocking combined with beam and floor interaction to achieve non-linear elastic behavior. This system behavior will eliminate the need for post-tensioning to achieve re-centering, but will introduce new parameters that can directly influence the lateral behavior. This research will study the effects of these parameters on the overall building behavior and will develop a methodology in which designers could use these parameters to strategically control the building seismic response. These key parameters will be investigated using parametric numerical analyses as well as large-scale, sub-system experimentation. One of the critical components of the system will be the hold-down, a device that connects the timber core to the foundation and provides hysteretic energy dissipation. Strength requirements and deformation demands in mid- to high-rise buildings, along with integration with mass timber, will necessitate the advancement of knowledge in developing this low-damage component. The investigated hold-down will have large deformation capability with readily replaceable parts. Moreover, the hold-down will have the potential to reduce strength of the component in a controlled and repeatable way at large deformations, while maintaining original strength at low deformations. This component characteristic can reduce the overall system overstrength, which in turn will have beneficial economic implications. Reducing the carbon footprint of new construction, linking rural and urban economies, and increasing the longevity of buildings in seismic zones are all goals that this mass timber research will advance and will be critical to the sustainable development of cities moving forward.
Project contacts are Linda Zimmer and Cory Olsen at the University of Oregon
During the testing and fabrication of mass timber projects a natural byproduct inevitably occurs in the form of offcuts and cutouts. In the case of new mass timber structures, the engineered wood materials are typically fabricated and prepared off site, allowing for the majority of the leftover materials to be made into useful products at the same facility already ideally set up for further digital fabrication. While the thickness of many of the spare panelized elements under investigation/production at TDI might seem excessive for smaller scale elements, the digital design and production techniques already being used allow for a fine degree of precision commensurate with furniture joinery. We propose to experiment with designing and fabricating furniture scale components and furniture prototypes as a way to reclaim these otherwise unused timber products. This project captures off cuts and remaindered materials from structural testing at TDI in both CLT and MPP panels.
Our focus is the design and fabrication of freestanding furnishings (ex: stools, benches, tables, chairs) that will exploit the technologies available at the Emmerson Lab. We come at this with two perspectives: in the first, products could be made directly from the materials available; in the second, the output will act as a formwork or “jig” to facilitate construction of an entirely new prototype that could expand into additional material languages. In either case it is important to us to share digital files of prototypes as “open source” designs so that production facilities and design professionals can work together to reduce waste and/or use our designs as a springboard to customize their own pieces. In this way we address the stated program goals to expand and develop new products and building components and to foster markets for these. Our iterative approach to digital design and digital hybrids utilizes CNC/robotic fabrication and assembly and we will be testing our ideas in a design-build format.
Project contact is Daniel Dowden at Michigan Technological University
This award will investigate a low-damage solution for cross-laminated timber (CLT) seismic force-resisting systems (SFRSs) using a novel uplift friction damper (UFD) device for seismically resilient mass-timber buildings. The UFD device will embrace the natural rocking wall behavior that is expected in tall CLT buildings, provide stable energy dissipation, and exhibit self-centering characteristics. Structural repair of buildings with these devices is expected to be minimal after a design level earthquake. Although CLT has emerged as a construction material that has revitalized the timber industry, there exists a lack of CLT-specific seismic energy dissipation devices that can integrate holistically with the natural kinematics of CLT-based SFRSs. CLT wall panels themselves do not provide any measurable seismic energy dissipation. As a payload to the large-scale, ten-story CLT building specimen to be tested on the Natural Hazards Engineering Research Infrastructure (NHERI) shake table at the University of California, San Diego, as part of NSF award 1636164, “Collaborative Research: A Resilience-based Seismic Design Methodology for Tall Wood Buildings,” this project will conduct a series of tests with the UFD devices installed on the CLT building specimen. These tests will bridge analytical and numerical models with the high fidelity test data collected with realistic boundary and earthquake loading conditions. The calibrated models will be incorporated in a probabilistic numerical framework to establish a design methodology for seismically resilient tall wood buildings, leading to a more diverse and eco-sustainable urban landscape. This project will provide local elementary school outreach activities, integrate participation of undergraduate minorities and underrepresented groups into the research activities, and foster graduate level curriculum innovations. Project data will be archived and made available publicly in the NSF-supported NHERI Data Depot (https://www.DesignSafe-CI.org). This award contributes to NSF's role in the National Earthquake Hazards Reduction Program (NEHRP).
The research objectives of this payload project are to: 1) bridge the fundamental mechanistic UFD models linking analytical and numerical models necessary for seismic response prediction of seismically resilient CLT-based SFRSs, 2) characterize the fundamental dynamic UFD behavior with validation and calibration through large-scale tests with realistic boundary conditions and earthquake loadings, and 3) integrate low-damage, friction-based damping system alternatives within a resilience-based seismic design methodology for tall wood buildings. To achieve these objectives, the test data collected will provide a critical pathway to reliably establish numerical and analytical models that extend the shake table test results to a broad range of archetype buildings. The seismic performance of mass-timber archetype building systems will be established through collapse risk assessment using incremental dynamic analyses. This will provide a first step in the longer term goal of establishing code-based seismic performance factors for CLT-based SFRSs.
Project contact is Vikram Yadama at Washington State University
The broader impact/commercial potential of this PFI project is in development of a commercially-viable process for manufacturing high-performing, durable mass strand timber panels for building construction from low-value and underutilized small-diameter softwood trees, such as from hazardous fuel thinning operations for improved forest health. The broader impacts are: (1) advancement of discovery and understanding while promoting teaching, training, and learning by including students and faculty in the research; (2) enhancement of infrastructure for research and education by establishing collaborations between interdisciplinary, yet complementary academic and industry stakeholders; (3) broadening of research dissemination to enhance understanding by involving industry and academia in the research, publishing project results in diverse media sources, and presenting research results in several formats that will benefit a wide range of forest products industry stakeholders; and (4) improved economic competitiveness of the U.S. forest products industry. In addition, if this proof-of-concept research leads to commercial applications, the benefits to society are: (1) new products with reduced environmental impacts, improved durability, and longer service-life; (2) technology that increases the U.S. forest products industry's competitiveness through creation of new jobs and increased opportunities for potential exports; and (3) increased use of wood, an environmentally-friendly, renewable, sustainable, and carbon-sequestering material.
The proposed project addresses challenges facing cross-laminated timber (CLT) panels in mass timber construction. Construction currently requires extreme care to protect CLT panels from moisture while ensuring long-term durability. Although builders take measures to reduce moisture exposure, it is inevitable that the CLT panels will take on water during their service-life. This project addresses these problems by utilizing thermal modification to produce chemical-free, mass timber panels with increased resistance to moisture and decay and improved dimensional stability. The goals are to: (1) evaluate process-performance relationships for thermal modification of small-diameter wood strands, and (2) demonstrate the feasibility of manufacturing high-performance cross-laminated strand-veneer lumber (CLSVL) mass timber panels. The objectives are to: (1) demonstrate the feasibility of utilizing thermally modified laminated strand veneer lumber for production of high-performance CLSVL panels, and (2) determine the potential environmental impacts of the new CLSVL panels. The technical results include validation of a repeatable process for thermally modifying small-diameter pine strands, validation of a method for manufacturing CLSVL panels, verification of physical and mechanical performance of the CLSVL panels, and establishment of commercially-viable process-performance relationships to enable commercial production of the CLSVL mass timber panels.
The development of this primer commenced shortly after the 2018 launch of the Mass Timber Institute (MTI) centered at the University of Toronto. Funding for this publication was generously provided by the Ontario Ministry of Natural Resources and Forestry. Although numerous jurisdictions have established design guides for tall mass timber buildings, architects and engineers often do not have access to the specialized building science knowledge required to deliver well performing mass timber buildings. MTI worked collaboratively with industry, design professionals, academia, researchers and code experts to develop the scope and content of this mass timber building science primer. Although provincially funded, the broader Canadian context underlying this publication was viewed as the most appropriate means of advancing Ontario’s nascent mass timber building industry. This publication also extends beyond Canada and is based on universally applicable principles of building science and how these principles may be used anywhere in all aspects of mass timber building technology. Specifically, these guidelines were developed to guide stakeholders in selecting and implementing appropriate building science practices and protocols to ensure the acceptable life cycle performance of mass timber buildings. It is essential that each representative stakeholder, developer/owner, architect/engineer, supplier, constructor, wood erector, building official, insurer, and facility manager, understand these principles and how to apply them during the design, procurement, construction and in-service phases before embarking on a mass timber building project.
When mass timber building technology has enjoyed the same degree of penetration as steel and concrete, this primer will be long outdated and its constituent concepts will have been baked into the training and education of design professionals and all those who fabricate, construct, maintain and manage mass timber buildings.
One of the most important reasons this publication was developed was to identify gaps in building science knowledge related to mass timber buildings and hopefully to address these gaps with appropriate research, development and demonstration programs. The mass timber building industry in Canada is still a collection of seedlings that continue to grow and as such they deserve the stewardship of the best available building science knowledge to sustain them until such time as they become a forest that can fend for itself.
Project contact is Lech Muszynski at Oregon State University
The aim of this project is to remove this vulnerability by thoughtful conceptualization of basic strategies for optimizing the design of mass timber buildings for successful post-use material recovery/reuse and end-of-life climate benefit. Research questions will include:
1. Is demolition of decommissioned mass timber buildings a viable end-of-life option at all?
2. Can deconstruction be conducted by following construction steps in reverse order?
3.What may be the extent of damage inflicted to the connection nests, connected edges and surfaces of MTP elements during a deconstruction?
4.Can original connection nests be safely reused in structures re-using deconstructed MTP elements?
5.What is the impact of techniques and technologies selected at the design, production, and construction stages on the EOL options and carbon cost of deconstruction,
6. What is the carbon impact of deconstruction on reuse or recycling of MTP elements?
7. Do the existing deconstruction companies in the Pacific northwest have capacity to process mass timber panels that could not be reused?
8. What is the carbon costs of transportation and repurposing/recycling of MTP elements for non-structural uses?
Project contacts are Arijit Sinha, Andre Barbosa and Barbara Simpson at Oregon State University
The results of this proposal will provide guidance on efficient design and analysis strategies for wood building construction including rocking/post-tensioned and pivoting spines, a next-generation seismic force resisting system, for improved performance, safety, sustainability, and economy. The use of wood in tall buildings is limitied by strength and stiffness considerations. The use of CLT and MPP shear walls, supplemented by energy dissipators may be able to aleviate this problem. Several knowledge gaps exist in terms of the performance of mass timber lateral force resisting systems (LFRS), interconnectivity and compatibility between the modules and LFRS-to-gravity system, and potential hybridization of structural materials for the gravity system and LFRS. The recent 2017 two-story shake table test is the only full scale dynamic on rocking CLT LFRS with energy dissipators. Importantly, since MPP panels are also a recent addition in the mass timber industry, no experimental data exist regarding the self-centering performance of post-tensioned MPP wall panels.
Project contacts are Andre Barbosa and Arijit Sinha at Oregon State University
In order to facilitate adoption of new mass timber products into practice, physical testing is required to understand and predict structural behavior. While extensive testing has been conducted at Oregon State on basic engineering properties of mass plywood panels (MPP) and MPP-to-MPP connections, there exists no experimental data on connections between MPP and other timber members (e.g. glulam) or on composite behavior of MPP with a concrete topping. Previous testing on CLT concrete-composite systems looked at different CLT-to-concrete connection systems, with HBV shear connectors-steel plates partially embedded in the timber with epoxy resin- as a strong candidate in terms of strength and stiffness performance. This project will focus on exploring the performance of MPP-concrete composite systems with HBV connectors.
Does it really cost more to build a high-performance building? Historically, this question has been addressed with theoretical studies based on varying the design of common building archetypes, but nothing beats the real thing. ZEBx, in partnership with BTY Group and seven builders from across BC, has completed a cost analysis of seven high-performance, wood-framed, mid-rise, multi-unit residential buildings that meet Step 4 of the Energy Step Code or the Passive House standard. The results of the study may surprise you!
Project contacts are Gerald Presley, Oregon State University, and Scott Noble, Kaiser+Path
The primary goal of this project is to enhance the durability of mass timber assemblies in high-moisture, high-termite risk regions. Only a few U.S. jurisdictions allow mass timber use by code adoption. Hawaii requires that all structural wood be treated to resist insects. Current topical or pressure treatments are allowed, but it is unclear how these treatments will perform in mass timber elements. Assembled cross-laminated timber (CLT) panels are too large to fit in pressure vessels. We will test the performance of individually treated wood members (lamella), assembled into CLT panels for compliance to structural requirements as well as resistance to termite attack in field trials. The resulting data will identify the most effective treatment options to protect CLT and other mass timber assemblies for use in Hawaii and similar regions with high termite exposure. The research implications will contribute to educating architects, engineers, builders and developers on modern timber construction in new regions.
Project contact is Mariapaola Riggio at Oregon State University
Earthquake engineers are focusing on performance-based design solutions that minimize damage, downtime, and dollars spent on repairs by designing buildings that have no residual drift or “leaning” after an event. The development of timber post-tensioned (PT), self-centering rocking shear walls addresses this high-performance demand. The system works by inserting unbonded steel rods or tendons into timber elements that are prestressed to provide a compressive force on the timber, which will pull the structure back into place after a strong horizontal action. But, because these systems are less than fifteen years old with just four real-world applications, little information is known regarding best practices and optimal methods for engineering design, construction and/or tensioning procedures, and long-term maintenance considerations. This project intends to contribute knowledge by testing both cross-laminated timber (CLT) and mass plywood panel (MPP) walls through testing of anchorage detailing, investigating tensioning procedures for construction, determining the contributions of creep on prestress loss over time, and comparing all laboratory test data to monitoring data from three of the four buildings in which this technology has been implemented, one of which is George W. Peavy Hall at Oregon State University. This will be accomplished by testing small- and full-scale specimens in the A.A. “Red” Emmerson Advanced Wood Products Laboratory, and small-scale specimens in an environmental chamber.
In the seismic design of structures according to the dissipative structural behaviour, the connection ductility is crucial in order to ensure the desired level of energy dissipation of the overall structure. Therefore, in case of ductile zones composed of dowel-type fasteners arranged in series, it is important to ensure that all the fasteners can fully develop their energy dissipation capacity by plastic deformations. However, when different types of connections made of two symmetrical and serially arranged assemblies of dowel-type fasteners are tested, it often appears that only few fasteners fully work in the plastic region while most of the remaining ones exhibit very low yielding.
Looking at the causes of this dysfunction, a possible explanation is due to the fact that the rules for the seismic design of dissipative zones in timber structures given in international codes and used in common practice often make reference only to the steel quality of the dowel-type fasteners specifying a minimum tensile strength or sometime, like is the case of the current version of Eurocode 8, only to maximum values of the dowel-type fastener diameter and of the thickness of the connected timber or wood-based members. Also, the research conducted so far about the ductile behaviour of serially arranged connections was not focused on the post-elastic properties of steel. However, for the seismic design of ductile zones of other materials, such as for example is the case of reinforced concrete walls, post-elastic characteristics of steel are required for the reinforcing bars, in order to achieve the desired dissipative behaviour.
Inspired by this fact, timber connections composed of serially arranged dowels made of steel grades with different hardening ratio and elongation at maximum tensile stress were fabricated and tested. The purpose of this work is to understand if the use of steel with significant post-elastic properties may help to solve the problem of limited yielding in serially arranged dowel-type connections.
The tested specimens were composed of two symmetrical timber members made of Glulam and LVL connected to two 6 mm thick slotted-in steel plates by means of 9 steel dowels with a diameter of 6.0 mm, which were subjected to monotonic and cyclic tests carried out by implementing dowels made of steel with favourable post-elastic properties.
The results showed that the simultaneous yielding of two serially arranged dowelled assemblies is possible, although not fully. Moreover, assuming as reference the steel grade with the lowest post-elastic properties, the connection ductility and strength measured through monotonic and cyclic tests increased by about 30% for the steel grades with the highest hardening ratio and elongation at maximum tensile stress, whereas the displacement at maximum strength was about five times higher.
In addition, it was found that confinement of the timber members and shaping of holes were crucial in order to avoid undesired and premature brittle failures and to increase the connection strength and ductility.
The results obtained may be useful in order to bring a reassessment of the code requirements regarding the steel properties of ductile connections as well as of certain principles of dimensioning and detailing.
Project contact is Erica Fischer, Oregon State University
Previous large-scale fire testing of mass timber buildings has occurred on a single floor of a building. The data collected from these experiments were used to demonstrate the fire performance of cross-laminated timber (CLT) buildings and to change the International Building Code (IBC) prescriptive fire protection design provisions for mass timber buildings. The scope of the tests was limited to compartment fires with varying levels of encapsulation. However, multi-story mass timber buildings are being constructed in the United States and fire science experts understand that fire threats can move beyond compartment fires and into travelling (moving fires) and vertical fire spread. In addition, many buildings are being proposed outside of the scope of the IBC prescriptive fire protection design approach (i.e. open floor plans), thereby requiring the employment of performance-based structural fire engineering. Performance-based structural fire engineering requires quantifying fire demands within the structure and calculating the resistance of the structure throughout the fire to provide safety to the occupants during egress, safety to fire fighters during and after the fire, and to ensure the building will not collapse introducing a threat of fire spread and damage to the surrounding buildings. To date, engineers are employing performance-based structural fire engineering on mass timber buildings; however, engineers are typically forced to make simplifications, be very conservative, and/or frequently use unproven assumptions. These simplifications and assumptions need to be tested experimentally to ensure that engineers are providing adequate levels of safety. Some of these assumptions include exterior wall and façade details that can prevent vertical fire spread, and detailing by engineers that considers the effects of charring during the decay phase of the fire.
The PIs have an opportunity to perform large-scale fire tests on a multi-story mass timber building in Corvallis, OR. Future large-scale fire tests will utilize a portion of the 10-story building being tested as a part of the Natural Hazards Engineering Research Infrastructure (NHERI) Tall Wood project (http://nheritallwood.mines.edu/). After the seismic testing of the 10-story building, the top four stories will be demolished and not utilized. Therefore, the research team will transport these floors to Corvallis to be re-assembled at the Corvallis Fire Training Center. In this preliminary stage, a multi-disciplinary team will perform computer simulation modeling of the fire tests, fully develop the scope of the tests and create a detailed experimental plan for the large-scale fire tests. The tests will be designed with considerations for the ability to address the following questions. These questions are consistent with future research needs that were identified by the Forest Products Laboratory  and the recent National Fire Protection Association (NFPA) Fire Safety in Tall Timber Buildings Workshop.
(1) How does the façade detailing of a mass timber building influence the vertical fire spread behavior?
(2) How can engineers better design mass timber buildings to enhance the safety for firefighters?
(3) How do glulam beam-to-column connections perform in real fires?
(4) What engineering solutions can be implemented within mass timber buildings to account for the behavior of the mass timber during the decay phase of the fire in the case that suppression is not available?
(5) How can engineers better design mass timber buildings to enhance the safety for fire fighters during the firefight and during overhaul/investigation?
Project contact is Yelda Turkan, Oregon State University
Over the past decade, fires have caused significant losses, both financial and through loss of lives, in timber buildings during construction (USFA 2020). Buildings under construction or in development are largely unprotected as they are not yet equipped with active fire protection systems (sprinklers), and for those buildings that are not designed for exposed timber, multiple floors are left exposed at a time as the fire protection trade trails in schedule behind the erection of the mass timber structural elements. With the addition of Type IVA, B, and C in the 2021 International Building Code (IBC), the IBC also adopted stricter requirements for mass timber buildings under construction. Under-construction mass timber buildings require that the mass timber is protected with noncombustible material within four levels of any construction more than six stories above grade. However, limited research has occurred to demonstrate that this construction sequence results in the optimal balance of safety, property loss, and cost.
The goals of this project are to: (a) develop a methodology to couple multiple commonly-used computational tools to evaluate the sequence of installation of passive fire protection in mass timber buildings under construction fire scenarios, (b) develop an analytical framework that can be implemented by industry to evaluate the risk and impact of fire protection construction sequencing on a job site while balancing property loss, cost, and life safety of construction workers due to a construction fire, and (c) identify knowledge gaps in fire dynamics in timber buildings that would increase the accuracy of predicting fire spread in mass timber buildings under construction.
The goals of this research are to gain a better understanding of the mechanics of timber moment-frame connections during two different fire scenarios: fire and post-earthquake fire. This research will develop the testing methodologies and benchmark data required to develop designs for the fire and post-earthquake performance of timber moment-resisting frame connections.
The project wIll test two moment resisting frame connections under fire and post-earthquake fire loading scenarios.
Full scale monotonic and cyclic loading tests on sub-assemblies for both connection types at the Emmerson lab.
Fire testing of structurally tested and un-tested specimens at the National Research Council (NRC) of Canada. These tests will occur under service loading conditions and will measure temperature gradients through the cross section of the connection, as well as displacements between the beam and column and residual cross section dimensions.
Data will be used to benchmark numerical models in order to perfom a parametric study that allows for varying of geometric parameters such as connection geometry and fastener configurations.
Sustainable Northwest (SNW) and Hacienda Community Development Group (HCDC), both based in Oregon, have proposed a plan to demonstrate pathways for building affordable housing with regionally sourced mass timber. In response to the region’s housing shortage, the partners’ proposal demonstrates the use of mass timber products while supporting efforts to educate stakeholders on wood product companies and forest restoration. The project outlines a plan to explore financing options, build one or more prototypes, and perform a structural material life cycle analysis.
Karagozian & Case (K&C), a science and engineering firm based in California, is seeking to develop and execute a two-phase testing program to demonstrate the blast-resistance capability of cross laminated timber (CLT). K&C’s proposal outlines a plan that will use full-size reinforced CLT panels to demonstrate that panels are capable of resisting severe blast, ballistic, and forced entry threats while still maintaining their bond line integrity under both quasi-static and dynamic loading conditions. If the proposed effort is successful, blast testing on reinforced CLT panels will be pursued in a follow-on second phase.