“…Similarly, Viau and Doudak (Viau and Doudak, 2021a, 2021b) conducted a series of tests on glulam beams aiming to better understand the performance of slender bolts within full-scale glulam assemblies, when subjected to blast loads perpendicular to the wood grain. Shock pressure waves were converted into two concentrated loads applied directly onto the specimens with an LTD 11 specimens with representative beam-to-floor connections were tested with various steel–wood–steel bolted connections, consisting of 12.7 mm diameter, 203.2 mm long bolts with 6.4 mm thick steel side plates, as shown in Figure 14(a).…”
Section: Performance Of Connectionsmentioning
confidence: 99%
“…Viau and Doudak reported that, overall, connections designed to yield in bolt bending performed better than those that were over-designed.Figure 14.(a) Representative wall-to-floor bolted connection; typical (b) bolt yielding and (c) wood crushing damage, and splitting failure in over-designed beams. Reprinted with permission of ASCE, from Viau and Doudak (Viau and Doudak, 2021a, 2021b); permission conveyed through Copyright Clearance Center, Inc.…”
The response of structures subject to impulsive loads remains a field of intense research. Whilst traditional construction materials, such as steel and concrete/masonry, have been the focus of most studies, further research on the performance of alternative materials for blast-resistant applications has been driven by their growing use in sustainable construction. Over the last years, engineers have been re-evaluating the use of timber as a prime construction material for a range of building types, from small office to high-rise residential buildings. As a result, there is now a growing need to study the blast resistance of timber structures, as they may become potential targets of terrorist attacks or being placed in the blast-radius of other critical buildings. A review of existing research on the blast resistance of timber structures is presented and key factors on the blast analysis and design of such structures are discussed. Most of the research has been conducted on light-frame wood stud walls, glued- and cross-laminated timber, and addresses material properties under high strain rates, typical failure modes, behaviour of structural connections and retrofitting solutions. Failure modes are reported to be highly dependent on the element layout and manufacturing aspects, and dynamic increase factors for the modulus of elasticity and maximum strength in the ranges of [1.05, 1.43] and [1.14, 1.60], respectively, have been proposed for different timber elements. Mechanical connectors play a significant role in dissipating energy through plastic deformation, as the brittle nature of timber elements compromises the development of their full capacity. Regardless the element type, SDOF models can accurately predict the dynamic response as long as idealised boundary conditions can be considered. Overall, although a good amount of research is available, more extensive research is needed to guide the design and engineering practice and contribute to the development of design codes and testing standards for timber structures under blast loading.
“…Similarly, Viau and Doudak (Viau and Doudak, 2021a, 2021b) conducted a series of tests on glulam beams aiming to better understand the performance of slender bolts within full-scale glulam assemblies, when subjected to blast loads perpendicular to the wood grain. Shock pressure waves were converted into two concentrated loads applied directly onto the specimens with an LTD 11 specimens with representative beam-to-floor connections were tested with various steel–wood–steel bolted connections, consisting of 12.7 mm diameter, 203.2 mm long bolts with 6.4 mm thick steel side plates, as shown in Figure 14(a).…”
Section: Performance Of Connectionsmentioning
confidence: 99%
“…Viau and Doudak reported that, overall, connections designed to yield in bolt bending performed better than those that were over-designed.Figure 14.(a) Representative wall-to-floor bolted connection; typical (b) bolt yielding and (c) wood crushing damage, and splitting failure in over-designed beams. Reprinted with permission of ASCE, from Viau and Doudak (Viau and Doudak, 2021a, 2021b); permission conveyed through Copyright Clearance Center, Inc.…”
The response of structures subject to impulsive loads remains a field of intense research. Whilst traditional construction materials, such as steel and concrete/masonry, have been the focus of most studies, further research on the performance of alternative materials for blast-resistant applications has been driven by their growing use in sustainable construction. Over the last years, engineers have been re-evaluating the use of timber as a prime construction material for a range of building types, from small office to high-rise residential buildings. As a result, there is now a growing need to study the blast resistance of timber structures, as they may become potential targets of terrorist attacks or being placed in the blast-radius of other critical buildings. A review of existing research on the blast resistance of timber structures is presented and key factors on the blast analysis and design of such structures are discussed. Most of the research has been conducted on light-frame wood stud walls, glued- and cross-laminated timber, and addresses material properties under high strain rates, typical failure modes, behaviour of structural connections and retrofitting solutions. Failure modes are reported to be highly dependent on the element layout and manufacturing aspects, and dynamic increase factors for the modulus of elasticity and maximum strength in the ranges of [1.05, 1.43] and [1.14, 1.60], respectively, have been proposed for different timber elements. Mechanical connectors play a significant role in dissipating energy through plastic deformation, as the brittle nature of timber elements compromises the development of their full capacity. Regardless the element type, SDOF models can accurately predict the dynamic response as long as idealised boundary conditions can be considered. Overall, although a good amount of research is available, more extensive research is needed to guide the design and engineering practice and contribute to the development of design codes and testing standards for timber structures under blast loading.
“…To strengthen timber connections against brittle failures, a few experimental studies (Zhang et al, 2019;Viau and Doudak, 2021) were conducted by employing different forms of reinforcements at normal temperature. The study conducted by Zhang et al (2019) showed that self-tapping screws (STS) can be used to enhance the bending strength, control crack propagation and significantly prevent splitting failure in dowel-type moment-resisting connections.…”
Section: Introductionmentioning
confidence: 99%
“…The study conducted by Zhang et al (2019) showed that self-tapping screws (STS) can be used to enhance the bending strength, control crack propagation and significantly prevent splitting failure in dowel-type moment-resisting connections. The results of Viau and Doudak (2021) who investigated the behaviour of bolted connections under blast loads show that reinforcing the connections with STS prevented brittle splitting failure at the connection and changed the failure mode to a combination of bolt yielding and wood crushing. Furthermore, the authors of the later study reported that employing STS promote more ductile behaviour when compared to that of unreinforced connections.…”
Section: Introductionmentioning
confidence: 99%
“…To strengthen timber connections against brittle failures, a few experimental studies (Zhang et al. , 2019; Viau and Doudak, 2021) were conducted by employing different forms of reinforcements at normal temperature. The study conducted by Zhang et al.…”
PurposeThe fire resistance of timber structures is heavily dependent on the fire behaviour of the connections between its structural elements. The experimental study presented in this paper aimed to investigate the fire performance of glued-laminated timber beam connections reinforced perpendicular-to-wood grain with self-tapping screws (STS).Design/methodology/approachTwo full-size fire experiments were conducted on glulam beam-end connections loaded in flexure bending. Two connection configurations, each utilizing four steel bolts arranged in two different patterns, were reinforced perpendicular to wood grain using STS. The bolt heads and nuts and the steel plate top and bottom edges were fire protected using wood plugs and strips, respectively. Each connection configuration was loaded to 100% of the ultimate design load of the weakest unreinforced configuration. The test assemblies were exposed to elevated temperatures that followed the CAN/ULC-S101 standard fire time–temperature curve.FindingsThe experimental results show that the influence of the STS was significant as it prevented the occurrence of wood splitting and row shear-out and as a result, increased the fire resistance time of the connections. The time to failure of both connection configurations exceeded the minimum fire resistance rating specified as 45 min for combustible construction in applicable building codes.Originality/valueThe experimental data show the effectiveness of a simple fire protection system (i.e. wood plugs and strips) along with the utilization of STS on the rotational behaviour, charring rate, fire resistance time and failure mode of the proposed hybrid mass timber beam-end connection configurations.
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