Auburn University’s (AU) School of Forestry and Wildlife Sciences (SFWS) in Alabama actively works to increase awareness of the benefits of CLT along with hybrid systems for more widespread adoption in multiple building segments. AU’s two-year project proposal outlines a plan that will establish a preliminary design for the usage of a timber-steel composite system, utilizing CLT or laminated veneer lumber (LVL), as an option that will replace reinforced concrete slabs to improve the structural performance for buildings six stories or more.
Hybrid composite glulam timber reinforced using deformed steel bars and epoxy resin adhesive (RGTSB), was significantly developed in Kagoshima University. In this paper, a beam-to-beam connection for RGTSB and experimental data on the connection are presented. Two 2:3-scaled simply-supported beams under four-point flexural bending in short-term loading, connection elements under short and long-term tension loading were tested. The connection for RGTSB beam performed on bending behaviour such as non-connection RGTSB beam, especially better on ductility.
Hybrid composite glulam timber reinforced using deformed steel bars and epoxy resin adhesive (RGTSB), was significantly developed in Kagoshima University. A long term laboratory investigation on a 4.5-meter-span hybrid timber beam and a non-hybrid timber beam was started from August 2011. The beam was made of RGTSB and another was of conventional glulam timber...
In this paper, bending behaviours in hybrid composite glulam timbers reinforced using deformed steel bars and epoxy resin adhesives (RGTSB) are presented. The technique RGTSB was developed in order to improve flexural stiffness and strength in glulam timbers...
This literature review aims to provide a general picture of retrofit needs, markets, and commonly used strategies and measures to reduce building energy consumption, and is primarily focused on energy retrofit of the building envelope. Improving airtightness and thermal performance are the two key aspects for improving energy performance of the building envelope and subsequently reducing the energy required for space heating or cooling. This report focuses on the retrofit of single family houses and wood-frame buildings and covers potential use of wood-based systems in retrofitting the building envelope of concrete and steel buildings.
Air sealing is typically the first step and also one of the most cost-effective measures to improving energy performance of the building envelope. Airtightness can be achieved through sealing gaps in the existing air barrier, such as polyethylene or drywall, depending on the air barrier approach; or often more effectively, through installing a new air barrier, such as an airtight exterior sheathing membrane or continuous exterior insulation during retrofit. Interface detailing is always important to achieve continuity and effectiveness of an air barrier. For an airtight building, mechanical ventilation is needed to ensure good indoor air quality and heat recovery ventilators are typically required for an energy efficient building.
Improving thermal resistance of the building envelope is the other key strategy to improve building energy efficiency during retrofit. This can be achieved by: 1. blowing or injecting insulation into an existing wall or a roof; 2. building extra framing, for example, by creating double-stud exterior walls to accommodate more thermal insulation; or, 3. by installing continuous insulation, typically on the exterior. Adding exterior insulation is a major solution to improving thermal performance of the building envelope, particularly for large buildings. When highly insulated building envelope assemblies are built, more attention is required to ensure good moisture performance. An increased level of thermal insulation generally increases moisture risk due to increased vapour condensation potential but reduced drying ability. Adding exterior insulation can make exterior structural components warmer and consequently reduce vapour condensation risk in a heating climate. However, the vapour permeance of exterior insulation may also affect the drying ability and should be taken into account in design.
Overall energy retrofit remains a tremendous potential market since the majority of existing buildings were built prior to implementation of any energy requirement and have large room available for improving energy performance. However, significant barriers exist, mostly associated with retrofit cost. Improving energy performance of the building envelope typically has a long payback time depending on the building, climate, target performance, and measures taken. Use of wood-based products during energy retrofit also needs to be further identified and developed.
This study aims to develop an improved understanding of the interfacial bond behavior of softwood glulam joints with bonded-in threaded steel rod. A total of 39 glulam joints with bonded-in single-threaded steel rods were tested to failure in the pull-pull configuration. The test results were presented in term of failure modes, load-relative movement response, pullout strength, and the corresponding slip. The distributions of bonded-in rod axial strain, interfacial bond stress, and relative movement were also analyzed to evaluate the local bond stress– relative movement response in the bond line. The results confirmed that the bond-relative movement response is dependent on the locations along the anchorage length, and the bond-relative movement responses located near both the loaded end and the anchorage end were observed to be stiffer than those at other locations. Finally, the predictions for the load capacity of the glulam joints with bonded-in threaded steel rod were carried out based on several existing empirical formulas.
Advanced sustainable lateral load resisting systems that combine ductile and recyclable materials offer a viable solution to resist seismic load effects in environmentally responsible ways. This paper presents the seismic response of a post-tensioned timber-steel hybrid braced frame. This hybrid system combines glulam frame with steel braces to improve lateral stiffness while providing self-centreing capability under seismic loads. The proposed system is first presented. A detailed numerical model of the proposed system is then developed with emphasis on the connections and inelastic response of bracing members. Various types of braced frames including diagonal, cross and chevron configurations are numerically examined to assess the viability of the proposed concept and to confirm the efficiency of the system. A summary of initial findings is presented to demonstrate usefulness of the hybrid system. The results demonstrate that the proposed system increases overall lateral stiffness and ductility while still being able to achieve self-centring. Some additional information on connection details are provided for implementation in practical structures. The braced-frame solution is expected to widen options for lateral load resisting systems for mid-to-high-rise buildings.
The anticipated growth and urbanization of the global population over the next several decades will create a vast demand for the construction of new housing, commercial buildings and accompanying infrastructure. The production of cement, steel and other building materials associated with this wave of construction will become a major source of greenhouse gas emissions. Might it be possible to transform this potential threat to the global climate system into a powerful means to mitigate climate change? To answer this provocative question, we explore the potential of mid-rise urban buildings designed with engineered timber to provide long-term storage of carbon and to avoid the carbon-intensive production of mineral-based construction materials.
This paper examines CLT-steel hybrid systems at three, six, and nine storey heights to
increase seismic force resistance compared to a plain wood system. CLT panels are used as
infill in a steel moment frame combining the ductility of a steel moment frame system with a
stiffness and light weight of CLT panels. This system allows for the combination of high
strength and ductility of steel with high stiffness and light weight of timber. This thesis
examines the seismic response of this type of hybrid seismic force resisting system (SFRS) in
regions with moderate to high seismic hazard indices. A detailed non-linear model of a 2D
infilled frame system and compared to the behavior of a similar plain steel frame at each
height.
Parametric analysis was performed determining the effect of the panels and the connection
configuration, steel frame design, and panel configuration in a multi-bay system. Static
pushover loading was applied alongside semi-static cyclic loading to allow a basis of
comparison to future experimental tests. Dynamic analysis using ten ground motions linearly
scaled to the uniform hazard spectra for Vancouver, Canada with a return period of 2% in 50
years as, 10% in 50 years, and 50% in 50 years to examine the effect of infill panels on the
interstorey drift of the three, six, and nine storey. The ultimate and yield strength and drift
capacity are determined and used to determine the overstrength and ductility factors as
described in the National Building Code of Canada 2010.
