Roadmap to developing a geometrical design guide for windcatchers

Light-frame wood construction constitutes a significant portion, approximately 90%, of the housing industry in Canada and the United States. Within this construction method, roofs are typically built either using prefabricated trusses or through stick-framing, where the roof structure is assembled on-site. Current building codes for stick-framing are largely based on historical practices and provide limited consideration for high-speed wind events, rendering these roof structures vulnerable to failure during tornadoes. This research addresses this vulnerability by proposing enhanced stick-framing guidelines designed to withstand EF-2 tornadoes. The study employs non-linear finite element analysis to model a stick-framed roof, initially designed according to the National Building Code of Canada. Connections between structural members are represented using non-linear links, while frame elements model the members themselves. An iterative performance-based design approach is applied: increasing wind loads are simulated, and upon identifying the first points of failure, the corresponding elements are improved. This process is repeated until the roof structure meets the performance target of resisting EF-2 tornadoes. Key issues identified and addressed during this process include the failure of roof-to-wall connections (RTWCs) and an insufficient number of members in the initial framing. The observed failure modes in the model are validated against damage survey photos from actual tornado events, revealing consistent patterns of structural failure. To improve the roof's resilience, several recommendations are put forth. A notable improvement involves an enhanced gable end frame, which increases the number of RTWCs and provides a more robust frame in areas subjected to the highest loads. Other suggested additions include the incorporation of struts, the use of hurricane ties at all RTWC locations, and an increased number of nails in various connections within the repeating inner frames. Minimum member sizes and material qualities for each roof structural component are also specified. The research highlights that the initial NBCC-compliant design fails at a mere 14% of the target EF-2 load, primarily due to RTWC weaknesses. This significant finding underscores the inadequacy of existing guidelines for tornado loads and emphasizes the need for the proposed improvements. The iterative design process reveals that the majority of structural elements experience their highest demand-capacity (D/C) ratios at the gable end frame, necessitating its strengthening. The implementation of specific gable end framing, including bracing and hurricane ties, significantly enhances the structure's capacity. Additionally, adding struts one-third of the way up the rafters, connecting them to the ceiling joists, effectively reduces moments in the members. Snow load cases also influence the design, particularly affecting rafter members and their connections to collar ties and ceiling joists. The final design incorporates these improvements, ensuring the roof can withstand both EF-2 tornado wind loads and significant snow loads. Comparison of the model's failure points with real-world tornado damage photos confirms the efficacy of the identified weak points. The failure of RTWCs, especially rafter RTWCs, and connections between rafters and ceiling joists, are common in both the model and actual tornado events. The proposed guidelines aim to provide easily implementable solutions for builders, promoting resilience in light-frame wood roof structures against tornado forces. The recommendations cover repeated inner framing connections, gable end frame specifications, and outrigger framing, alongside detailed specifications for nails, spacing, and bracing. These findings bridge a critical knowledge gap in stick-framing construction for tornado-prone regions, suggesting a feasible design approach for EF-2 level tornado resistance, with potential for adaptation to other roof types and sizes. #LightFrameConstruction #WoodRoofs #TornadoWindLoads #EF2Tornado #StickFraming #NonLinearFiniteElementAnalysis #BuildingCodes #PerformanceBasedDesign #RoofToWallConnections #StructuralResilience #GableRoofDesign #HurricaneTies #ConstructionGuidelines

The selection of window treatments for a home can significantly impact a room's aesthetic and functionality. Natural light is a crucial element in interior design, and window dressings serve to enhance or control this aspect. Three Dallas-Fort Worth designers offer insights into the do's and don'ts of choosing and installing window treatments, covering various considerations from practical needs to decorative flair. Functionality should be the primary consideration when selecting window treatments. These coverings are essential for blocking or filtering light, ensuring privacy, and providing insulation against temperature fluctuations. Designer Holly Hickey Moore emphasizes that the functional aspects, such as privacy and light control, should be addressed before decorative elements. For instance, if a homeowner desires privacy without entirely blocking light, semi-sheer drapes or cafe curtains are suitable options. Cafe curtains, which hang from the middle of the window, are particularly effective in ground-floor bedrooms or rooms facing public areas, allowing light to enter while maintaining privacy. The placement of furniture also influences the choice of window treatments; for example, a shade might be more appropriate than drapes if a couch is positioned in front of a window. Window treatments should not obstruct natural light or detract from appealing outdoor views. Designer Kim Armstrong advises against shutters, as they can significantly reduce light filtration and introduce an additional hard surface, altering the quality of light within a room. Shutters are estimated to block about 70% of incoming light, even when open. Similarly, Noel Pittman suggests that if a room offers a beautiful exterior view, simpler window treatment designs are preferable to bold patterns that could create a distraction. The aim is to complement the view, not overshadow it. Layering different window treatments can create a sophisticated and functional look. Pittman often incorporates natural-fiber blinds, such as those from Hartmann & Forbes, behind curtains to add warmth and additional privacy without completely blocking light. When combining a window shade with curtains, Moore recommends an outside-mount shade, installed above the window frame at the same height as the curtain rod. This arrangement prevents an awkward gap between the top of the window and the rod, creating a cohesive appearance. Proper installation of window treatments is critical for maximizing their aesthetic impact. Hanging curtain rods too low or too close to the window can visually diminish a room's height. Armstrong recommends mounting rods closer to the ceiling or crown molding to create an illusion of vertical expanse. Additionally, extending the curtain rod six to eight inches beyond the window frame allows the curtains to be drawn back fully, exposing the entire window and maximizing light entry. For shades, an outside-mount option typically allows more light than an inside-mount shade, which can obscure part of the window. Regarding drapery length, preferences vary among designers; some prefer curtains that skim the floor for a tailored look, while others favor a slight pooling on the floor for a more relaxed aesthetic. The choice of fabric is also paramount. Armstrong prefers cotton and linen for their graceful drape, often using printed window treatments in rooms with simple, painted walls and more subtle options in wallpapered rooms. Moore suggests selecting patterns that will remain appealing over time, favoring small-scale or classic block-print designs for a timeless appeal. While plain panels have been a long-standing trend, there is a resurgence of more decorative elements like valances and cornice boards, influenced by English design. Adding decorative trims, such as tassels or poms, can introduce texture, color, and uniqueness to plainer curtains. Investing in custom window treatments is often recommended, despite the higher cost, to ensure a perfect fit, fullness, and impactful design. While Armstrong typically avoids pre-made options, she acknowledges resources like Anthropologie and Pepper Home for curated choices. Cost-saving measures for custom treatments include using less expensive fabrics, selecting solid colors (which require less fabric due to no pattern repeat), or choosing wide-width fabrics to reduce the number of panels needed. Designers often note that the savings from pre-made options are minimal once hemming and lining costs are considered, reinforcing the value of a quality custom investment. #WindowTreatments #InteriorDesign #HomeDecor #Drapery #PrivacySolutions #LightControl #CustomFabrics #DesignTips #HomeImprovement

The devastating impact of severe tropical cyclones in Australia during the 1970s, particularly Cyclones Althea and Tracy, underscored the critical need for integrating research-based structural engineering principles into residential building design and construction. Historically, house construction relied on traditional methods that evolved slowly, rendering them vulnerable to extreme weather events compared to engineered structures. The inherent structural redundancies and complex load paths within houses complicated their analysis, prompting the Cyclone Testing Station (CTS) to initiate full-scale house testing in the early 1980s. These initial tests involved static multipoint loading of an older house slated for demolition, followed by comprehensive testing of nine full-scale houses under both static and cyclic loading. This extensive testing program aimed to understand load paths in various house types, incorporating different building practices and materials, and its findings were instrumental in amending Australian house construction codes, standards, and manuals. Over time, advancements in computer modeling and instrumentation have enabled more sophisticated full-scale studies. Current research benefits from real-world data on houses under construction, allowing for analytical models that account for the variability in connection strengths, an aspect difficult to capture in single tests. This approach facilitates the study of progressive failure in timber-framed housing systems, distinguishing between structures that sustain significant damage and those with limited damage during the same wind event. These studies integrate wind tunnel investigations to map temporal pressure distributions, full-scale multiple tests on connections (including those with construction defects) to establish statistical distributions of strength and load/deflection relationships, and full-scale tests on complete houses or sections thereof to determine load-sharing mechanisms among parallel structural and non-structural elements. The test program results serve to calibrate analytical models, which are subsequently used for reliability studies. Early full-scale tests by CTS involved applying simulated wind loads to various house types, including a high-set house, a single-story house with a concrete floor, a Tongan hurricane house, brick veneer houses for both cyclonic and non-cyclonic regions, a light-gauge steel-framed panelized building, and a split-level brick veneer house. These tests provided crucial insights into vulnerable elements and load paths. For instance, initial tests consistently revealed that at least one element or connection failed below the design load, often due to low-cycle fatigue. However, after minor design modifications, the houses could resist significantly higher loads. The tests also demonstrated that non-structural elements, such as cornices, played a crucial role in transferring wind loads, creating stiff and direct load paths. Furthermore, the studies highlighted the importance of structural redundancy, where parallel elements could share loads, mitigating the risk of significant damage from the failure of a single weaker element. Limitations of these early tests included the challenge of replicating construction variations and the generalized nature of simulated wind loading compared to actual spatial and temporal wind pressure fluctuations. Recent research has expanded full-scale testing to focus on house roofs, examining structural response and load sharing. Unlike studies in North America and Canada, Australian research addresses the unique construction types prevalent in the region. This involves combining full-scale tests on house sections with numerical models, characterizing component variability, and utilizing detailed wind tunnel loading data. Investigations into contemporary house construction practices, informed by surveys, revealed deficiencies in design and installation, such as incorrect site classifications and faulty connections. These deficiencies are now being incorporated into full-scale tests to understand their role in progressive failure and the effectiveness of redundancies. For example, testing of truss-to-wall connections, both ideal and defective, demonstrated how wall linings and cornices contribute to load sharing around weak connections. Finite element models, validated against experimental data, further explore load sharing and structural responses under various defect scenarios. Another area of recent focus is the progressive failure and load redistribution of batten-to-truss connections. Laboratory tests on both new and aged connections, subjected to static and dynamic wind loads, showed significant variability in strength and highlighted the impact of nail slip on connection performance. Wind tunnel studies provided time-history data of loadings on roof elements, revealing correlations between peak loads on adjacent connections, which is critical for understanding the initiation of progressive failures. Non-linear finite element analysis simulated load redistribution as connections fail, showing how loads are shared among neighboring connections based on the stiffness of battens and cladding. The analysis indicated that connection failures can cascade rapidly, emphasizing that while some elements provide redundancy, critical connections near the cladding have limited load-sharing capacity, making it essential for each connection to meet its design load. This ongoing research continues to quantify the varying resilience of connections within houses, contributing to more robust and wind-resistant building practices. #WindLoads #StructuralTesting #HouseConstruction #BuildingCodes #CycloneResistance #TimberFramedHouses #ProgressiveFailure #LoadPaths #FiniteElementModeling

Mar Ricketts, the principal and founder of GuildWorks LLC, has a background influenced by a childhood interest in flying kites and architecture. His company specializes in the design, specification, fabrication, and installation of permanent and temporary tension and fabric structures. Initially, GuildWorks produced performance kites in the mid-1990s, including an indoor kite that didn't rely on wind. Ricketts notes that kites provided a foundational understanding of tension-suspended airfoils and lightweight fabric structures, directly correlating to fabric structure design. This expertise led to requests for backdrops for theatrical and corporate events, eventually evolving into the company's current focus on fabric structures for diverse applications. GuildWorks' projects now include plazas, courtyards, building entryways, spaces between buildings, civic structures, ETFE structures, pavilions, amphitheaters, fabric facades, interior spaces, and public art. The company strategically shifted its emphasis from temporary installations to permanent structures over the last decade, aiming for projects with longer life cycles, greater impact, and enhanced sustainability. Ricketts' architectural interest, stemming from a boyhood experience of designing his family's home and drafting its construction documents, fostered an early understanding of structural design and construction. This experience, combined with his studies in engineering and architecture at the Pratt Institute, prepared him to innovate in lightweight structures. Driven by the desire to create impactful and permanent structures, Ricketts states that architecture defines spaces, transforming an undefined area into a functional and communal environment. GuildWorks, employing 20 to 25 people, now measures its success by the scale and permanence of its projects. A significant project involved the redevelopment of Riverfront Park Pavilion in Spokane, Wash., originally built for the 1974 World’s Fair. GuildWorks spent over 18 months on this multi-million dollar project, which required extensive engineering to incorporate new tension elements supporting 72 custom-designed panels. These panels provide shade and enhance the park's outdoor gathering space, transforming the pavilion into an iconic symbol of downtown Spokane. The company's focus on permanent projects proved beneficial during the 2020 pandemic, allowing GuildWorks to continue its growth despite challenges that would have significantly impacted an events-focused company. While still undertaking temporary structures, GuildWorks prioritizes projects that push design boundaries, promote sustainability, foster community, and leave a lasting impression. Ricketts advocates for greater recognition of fabrics and membranes as standard building materials, comparable to glass, stone, or wood. He plans to release a book, "Visionary Building: Weave Technology & Natural Design to the Spectacular," to inspire developers and investors to consider innovative, sustainable design approaches. Ricketts observes a growing trend towards sustainability within the specialty fabrics industry, with an increased focus on environmental impact. He notes that advanced architectural fabrics offer numerous ecological benefits, such as reducing heat island effects, collecting water, filtering pollution, regulating temperature, and ensuring ample airflow. GuildWorks aims to be at the forefront of these environmental changes, integrating planetary care into its business model beyond just financial gain. The company's "City Square Shade" project for an office complex in Phoenix, Ariz., exemplifies their work in creating usable, shaded spaces, highlighting the often-underestimated importance of shade and fabric in architectural design. #MarRicketts #GuildWorks #FabricStructures #ArchitecturalDesign #TensionStructures #SustainableArchitecture #KiteDesign #PermanentStructures #SpecialtyFabrics