Andrew Buchanan

• University of Canterbury

Link to the book Fire Safe Use of Wood in Buildings - Global Design Guide for Open Access digitalt and order of hardbound book: https://doi.org/10.1201/9781003190318

Structural systems with ductile connections have been proposed for multi-storey timber buildings based on research conducted over the last decade. The members designed with unbonded post-tensioning for recentering and energy dissipation through the mild steel elements exhibit almost complete re-centering capacity and significant energy dissipation...

With the increasing demand for multi-storey timber buildings in areas with high wind loads and high seismic activity, stiff lateral load resisting systems are becoming a crucial design component. Post-tensioned Pres-Lam mass timber lift shafts and stairwell core walls not only provide a strong and very stiff lateral load resisting system, but also...

Tall timber buildings are becoming popular around the world. This paper discusses options for setting the level of fire resistance in multistorey timber buildings. Fire resistance of timber structures involves a paradox, because it is well known that heavy timber construction has excellent fire resistance in severe fires, but it is also well known...

Structural wall panels Laminated veneer lumber (LVL) have been proposed for enhanced seismic resistance of multi-storey timber buildings based on research performed at University of Canterbury, New Zealand. The system is designed to be self-centering with unbonded post-tensioning and dissipate energy through ductile connections. This paper describe...

This paper describes the performance of log houses in the 2016 Kaikoura earthquake. Most of these houses are in the Mt Lyford village 45 km south-east of Kaikoura. Typical log houses at Mt Lyford were built using 200mm diameter machined logs. A smaller number of log houses were built with much larger hand-hewn logs of less regular shapes, in tradit...

Tall timber structures require lateral load-resisting elements which are very stiff and strong without complex connections. Post-tensioned timber (Pres-Lam) walls provide such properties and can also limit damage in case of extreme seismic events. Low damage can only be guaranteed if the connections between the walls and the diaphragm can transfer...

The scope of this paper is to quantify the advantages of using unbonded longitudinal posttensioning for long-span timber beams. This sustainable system can be a suitable alternative to more traditional prestressed concrete and (nonprestressed) glulam or LVL solutions. Unbonded posttensioning provides enhanced performance at serviceability limit sta...

This chapter outlines methods of assessing the adequacy of building components in fire conditions. It quantifies the requirements for design and provides alternative means of achieving these. The chapter outlines methods of quantifying the severity of post-flashover fires, for comparison with the provided fire resistance, including the concept of e...

This chapter introduces the overall strategy for providing fire safety in buildings, and identifies the roles of fire resistance and structural performance as important parts of that strategy. One of the more durable frameworks for fire safety assessment is the Fire Safety Concepts Tree developed by the National Fire Protection Association (NFPA)....

This chapter describes some common examples of composite construction and provides simple calculation methods of design for fire exposure. These simple calculation methods follow guidance in Eurocode 4 Part 1.2. Tabulated data are very helpful for simple design of beams and columns of composite structures, because simple calculation methods only ex...

This chapter describes the process of designing structures to resist fire exposure. It also describes some simple tools for making structural calculations, and explains the importance of loads and support conditions in estimating load capacity under fire conditions. Structural design for fire is conceptually similar to structural design for normal...

This chapter discusses fires in rooms and heat transfer to structural members. It reviews the combustion of fuels in typical building fires, and the factors that affect fire growth. Estimation of temperatures in post-flashover fires is an essential part of structural design for fire safety. Temperatures in post-flashover fires are usually of the or...

This chapter describes the fire behaviour of light frame construction using timber and steel components, and reviews available design methods. Light frame construction can have excellent fire behaviour, provided that it is well constructed from the correct materials. Experience in many fires has shown that gypsum board linings can prevent fire spre...

This introduction presents an overview of key concepts discussed in the subsequent chapters of this book. The book introduces the structural design of buildings and building elements exposed to fire. The emphasis is on understanding structural behaviour in fire from first principles, allowing structural fire safety to be provided using rational eng...

This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book outlines the recommendations for structural design of fire-exposed buildings constructed from structural steel, concrete or timber. The overall design approach is to compare the estimated fire severity with the fire resistance of...

This chapter introduces advanced calculation methods, and highlights their advantages and disadvantages. It also discusses the required components of software for advanced calculations. Advanced calculation methods range from fire models that describe how compartment fire temperatures develop over time to models that predict temperatures in fire-ex...

This chapter provides the information needed for calculating the performance of steel buildings exposed to fires. Simple methods are described for designing individual steel members to resist fire exposure, including calculations of elevated temperatures, methods of fire protection, and information on thermal and mechanical properties of steel at e...

This chapter describes simple methods of designing reinforced concrete structures to resist fires, including information on thermal and mechanical properties of concrete at elevated temperatures. Calculation of the behaviour of concrete structures in fire depends on many factors, the most important being the fire limit state loads on the structure,...

This chapter describes the fire behaviour of timber structures, and gives design methods for heavy timber structural members exposed to fire. 'Heavy timber' or 'massive wood' construction describes all uses of large dimension timber framing in buildings. Glue laminated timber (glulam) describes timber members which are manufactured from several sol...

This paper analyses the lateral load performance of a post-tensioned timber (Pres-Lam) frame which was designed with the primary function of supporting gravity loading. A full scale, two bay frame was used and subjected to quasi-static horizontal displacement. A total of four tests were performed, one with only the post-tensioning cables to resist...

The lateral stability of buildings during and after fire is of interest to fire-fighters, for protection of other property, and for post-fire investigators who may access buildings after a fire has occurred. A common approach for designing for lateral stability in New Zealand (NZ) is to provide sufficient resistance to ensure that a fire-rated stru...

This article presents recent research on the seismic resistance of coupled post-tensioned timber walls for use in multi-story buildings. The walls are constructed from laminated veneer lumber (LVL), post-tensioned with unbonded vertical tendons, and coupled together with mild steel U-shaped flexural plates (UFPs) as energy dissipating elements. The...

Prestressed-laminated timber (Pres-Lam) design has recently been adopted for multistory timber buildings based on ongoing research at the University of Canterbury, New Zealand. This system combines large timber members with unbonded posttensioning for recentering and ductile connections for energy dissipation. This paper describes the experimental,...

This paper describes part of a larger research initiative to predict the fire resistance of engineered timber floor systems. The floor systems described in this paper are prefabricated modular joist and box beam floors, designed for multi-storey building use with spans of five to seven metres. The paper describes 3D numerical modelling of the floor...

This paper describes numerical modelling to predict the fire resistance of engineered timber-concrete composite floor systems. The paper describes 3D numerical modelling of the floor systems using finite element software, carried out as a sequential thermo-mechanical analysis. Experimental testing of these floor assemblies has also been undertaken...

Moment-resisting frames made of laminated veneer lumber (LVL) in combination with unbonded post-tensioning have recently been proposed for multi-storey timber buildings. Prefabricated and post-tensioned timber frames can be designed to have enhanced re-centering and energy dissipation after seismic loading. The unbonded post-tensioning provides re-...

This paper describes a simplified calculation method that can be used to predict the fire performance of post-tensioned timber box beams. Despite being a combustible material, timber beams can perform well in fire. However, post-tensioned timber box beams need to be carefully designed if an undesirable shear failure mode is to be avoided. A simplif...

This article describes tests investigating a feasible source of passive damping for post-tensioned glue-laminated (glulam) timber structures. This innovative structural system adapts precast concrete PRESSS technology [Priestley et al., 1999] to engineered wood products combining the use of post-tensioned tendons with large timber members. Current...

The paper presents a numerical model for predicting the fire resistance of timber members. Fire resistance is evaluated in a two‐step process implemented in the Abaqus finite element code: first, a time‐dependent thermal analysis of the member exposed to fire and then a structural analysis under a constant load are performed. The structural analysi...

This paper examines charring rates for different cross‐sections of single and double timber beams made from laminated veneer lumber, with nailed, screwed or glued connection types for the double beams. Charring rates and burning characteristics were examined both in a small furnace and in a larger pilot furnace. The bottom charring rates were somet...

In a bid to accurately model structural behaviour of timber buildings in fire, a number of obstacles have been identified which must be fully understood before advanced computer modelling can accurately be used to represent physical behaviour. This paper discusses the obstacles, with suggestions on how to mitigate them, incorporating the challenges...

In a bid to accurately model structural behaviour of timber buildings in fire, a number of obstacles have been identified which must be fully understood before advanced computer modelling can accurately be used to represent physical behaviour. This paper discusses the obstacles, with suggestions on how to mitigate them, incorporating the challenges...

In fire design for floors, the three criteria of stability, integrity and insulation are required for the specified fire resistance duration. Among these, stability is not easy to confirm. For solid prestressed concrete slabs of uniform thickness, Eurocode 2 provides tabulated data and specifies an axis distance to the centroid of strands to achiev...

This paper describes initial experimental testing to investigate feasible sources of passive damping for the seismic design of post-tensioned glue laminated timber structures. These innovative high performance structural systems extend precast concrete PRESSS technology to engineered wood structures, combining the use of post-tensioning bars or cab...

Despite big advances in analytical modelling of the performance of structures exposed to fire, there has been difficulty in modelling the fire performance of precast prestressed concrete floor slabs in multi storey buildings. The fire resistance of these floor systems is heavily influenced by the end connections and the stiffness of the surrounding...

Universities are under continual pressure to reduce the expense associated with the laboratory education of undergraduate engineering students. Many alternatives to traditional laboratory instruction have been tested to improve educational benefits and to reduce academic input. This paper describes the benefits of laboratory classes run in an inter...

Current regulations on the use of structural timber in large multi-storey buildings can be restrictive due to a perceived higher level of risk with regards to fire safety. This research investigates the fire performance of unprotected timber floors for use in these types of buildings, involving both modelling and experimental testing. To fully char...

The NMIT Arts & Media Building in Nelson, New Zealand is the first in a new generation of multi-storey timber structures. It employs a number of innovative timber technologies including an advanced damage avoidance earthquake design that is a world first for a timber building. Aurecon structural engineers are the first to use this revolutionary Pre...

This paper outlines the study of a 2-storey timber building at the University of Canterbury, in Christchurch, New Zealand. The building consists of post-tensioned timber frames and walls for lateral and gravity resistance, and timber concrete composite flooring. Originally a test specimen, the structure was subjected to large lateral displacements...

Laminated veneer lumber (LVL) structural members have recently been proposed for multi-storey timber buildings based on ongoing research at University of Canterbury, New Zealand. The members are designed with unbonded post-tensioning for recentering and ductile connections for energy dissipation. This paper describes the experimental and numerical...

Structural timber innovations in New Zealand have led to the emergence of post-tensioned timber buildings as a viable structural system for multi-storey commercial buildings. Extensive experimental testing and analysis has enabled the development of analytical prediction techniques for the lateral response of post-tensioned timber frame and wall st...

Design of structural systems for commercial and multi-residential buildings throughout most parts of the world, is currently dominated by the use of reinforced and / or prestressed concrete construction, usually supported by steel or concrete beams and frames. However, recent developments throughout the world have demonstrated the potential for tim...

The earthquake on 22 February 2011 was very close to Christchurch city, generating very high level ground excitations that caused severe geotechnical effects and widespread structural damage. This paper outlines the wide range of damage to houses resulting from liquefaction, lateral spreading, rockfall, and horizontal and vertical ground accelerati...

The September 2010 and February 2011 earthquakes in Canterbury, New Zealand resulted in significant ground excitations that caused severe geotechnical effects and widespread structural damage. This paper outlines the various forms of damage to different types of engineered timber structures, including timber water tanks. Most of the damage resulted...

This paper describes a series of experiments to obtain the embedment strength of wood at elevated temperatures. The results will be used in Johansen's yield equations to predict the fire resistance of nailed, screwed, and bolted timber connections. To date, Johansen's yield equations have only been used at ambient temperatures. Embedment strength v...

This paper describes the development of post-tensioned timber frames for multi-storey timber buildings. Post-tensioned timber beams and frames give opportunities for much greater use of timber and engineered wood products in large buildings, using innovative technologies for creating high quality buildings with large open spaces, excellent living a...

This research investigated the fire performance and failure behaviour of timber-concrete composite floor systems currently under development in New Zealand, resulting in a design method for evaluating the fire resistance of these floors with different types of connections. Furnace tests were performed on two full-size floor specimens at the Buildin...

On the basis of recent developments in post-tensioned multi-storey timber buildings using unbonded tendons, this paper aimed at investigating the potential of implementing a similar technology for innovative solutions for timber bridges. In particular, several technological solutions are proposed for future development, using several different cros...

Glulam rivets are special nails for making high strength connections in timber structures. This paper describes an investigation of glulam rivet behaviour in radiata pine timber grown in New Zealand. Test results are compared with those on Canadian species, and with several international codes. The European yield theory is shown to give excellent p...

Combined bending and axial loading is often encountered in lumber and timber members. Existing design methods are based on studies carried out many years ago, and are no longer appropriate because they do not recognize that wood with defects behaves in compression as a nonlinear ductile material and in tension as an elastic brittle material subject...

This paper represents a new approach to size effects in timber. The design process in Canadian Standards Association code CAN3-086-M80 allows for size effects in shear and in tension but not in bending. A large number of bending test results arc analyzed in this paper to show that size effects in bending are very important. A modification is made t...

This paper describes a modelling comparison between three very similar medium sized educational buildings located in the temperate climate of Nelson, New Zealand, each designed using structural systems made primarily of timber (actually built), concrete or steel (both hypothetical). The buildings were analysed using two different insulation values...

Recent advances in timber design at the University of Canterbury have led to new structural systems that are appropriate for a wide range of building types, including multi-storey commercial office structures. These buildings are competitive with more traditional construction materials in terms of cost, sustainability and structural performance. Th...

Design of structural systems for commercial and multi-residential buildings throughout most parts of the world, is currently dominated by the use of reinforced and / or prestressed concrete construction, usually supported by steel or concrete beams and frames. However, recent developments throughout the world have demonstrated the potential for tim...

The fire performance of precast prestressed concrete floor slabs in multi storey buildings is heavily influenced by the end connections and the stiffness of the surrounding structure, both of which must be considered in any analysis. Previous “traditional” studies have modelled the floor slabs with beam or shell elements in which the end nodes shar...

This paper focuses on the observed seismic performance of residential houses (mainly single-storey and two-storey houses) in the Darfield earthquake on 4 September 2010 and identifies potential research areas for remediation and resilience. Overall the residential building stock, consisting predominately of light timber frame construction, performe...

This paper describes a series of experiments to obtain the embedment strength of wood at elevated temperatures. The results will be used in Johansen's yield equations to predict the fire resistance of nailed, screwed, and bolted timber connections. Johansen's yield equations are used in Europe and USA to predict the ultimate strength of bolted or d...

Recent advances in the design of multi-storey timber buildings have led to viable structural systems that allow open floor plans with large spans between frames and/or walls. Timber-concrete composite (TCC) flooring can achieve the spans required but have the potential to be flexible under diaphragm actions, which can significantly alter the seismi...

The fire resistance evaluation of a timber member is an important and complex problem of structural design. In order to solve this problem, it is crucial to have reliable information on the temperature distribution within a timber cross-section exposed to fire, and to develop a numerical model for the prediction of such a quantity. The paper report...

The scope of this paper is to highlight the advantages of using longitudinally post-tensioning for long-span timber beams compared to traditional glulam or LVL solutions. The analysis is limited to serviceability limit states for gravity loads. An analtycal iterative procedure which takes into account tendon elongation within beam deflecting has be...

The ultimate strength of bolted and dowelled connections in timber members at ambient temperatures have been assessed using Johansen’s yield equations in Europe and USA. More recently, several researchers have begun to investigate the strength of bolted and dowelled connections at elevated temperatures. Research has been carried out at the Universi...

Several factors can affect the behaviour of the hollowcore floor slabs in fire. This paper analytically investigates the relationship between the fire resistance of the overall floor system and the floor length to width ratio as well as the type of side supports. The study uses beam grillage and shell elements to model the hollowcore slabs and the...

Structural frames made of prefabricated laminated timber beams and columns connected by unbonded post-tensioning and additional mild steel reinforcement have recently been proposed for multi-storey timber buildings (referred to as "Pres-Lam®" technology). The benefits of post-tensioning to assemble prefabricated timber elements are rapid erection,...

This paper reports the experimental results of symmetrical push-out tests performed on notched and toothed metal plate connectors for laminated veneer lumber (LVL)-concrete composite floor systems. The characteristic shear strength and slip moduli were evaluated for three types of connectors: (1) a 300-mm-long rectangular notch cut in the LVL joist...

Recent structural timber innovations at the University of Canterbury have led to the design, construction and experimental testing of a large scale, 2 storey, post-tensioned timber frame and wall building. The building system, referred to as Pres-Lam®, aims to minimise on-site construction time and building cost, to compete with alternative constru...

This paper describes new design strategies for increasing the thermal mass to reduce the operational energy for space-conditioning of timber buildings. This paper compares energy performance of multi-storey timber buildings (low thermal mass) with the energy performance of conventional concrete buildings (high thermal mass). A computer model of eac...

This paper reports the outcomes of short-term collapse tests performed on eleven LVL (laminated veneer lumber)-concrete composite floor T-beams. Different variables such as span length (8 and 10 m), connection and concrete type, and design level (well-and under-designed, in terms of connector numbers) were investigated. During the tests, mid-span d...

The paper presents a numerical model implemented in the Abaqus finite element code for fire resistance of timber members. The fire resistance is evaluated in a two-step process: first, a thermal analysis of the member exposed to fire is carried out, and then a structural analysis under a constant load is performed over time. In the structural analy...

The use of structural timber systems in large multi-storey timber buildings is restricted due to current fire regulations and a perceived level of risk. This research investigated the fire performance and failure behaviour of timber-concrete composite floors currently under development in New Zealand. Furnace tests were performed on two full-size f...

This paper develops the concept of carbon footprinting for multi-storey buildings, comparing either timber or steel or concrete as the main structural material. Life cycle assessment is used to quantify the green house gas emissions derived both from the production of the buildings' materials (cradle-to-gate), as well as the total emissions over th...

This paper describes an investigation into the fire performance of epoxied connections between steel rods and laminated veneer lumber (LVL) made from radiata pine. To determine connection performance, a four-phase experimental investigation was carried out on the axial tensile strength of a connection that utilised a threaded steel rod bonded into...

An extensive research program is on-going at the University of Canterbury, New Zealand to develop new technologies to permit the construction of multi-storey timber buildings in earthquake prone areas. The system combines engineered timber beams, columns and walls with ductile moment resisting connections using post-tensioned tendons and eventually...

Recent structural timber innovations in New Zealand have let to the construction and experimental testing of a large scale, 2 storey, post-tensioned timber building. The building is subjected to quasi-static cyclic seismic testing up to design level Drifts of 2%. The influence of concrete diaphragms, additional mild steel reinforcement and column r...

This paper describes an investigation into the fire performance of bolted tensile connections in laminated veneer lumber (LVL) made from radiata pine. The capacity of the bolted connections depends on the embedment strength of the wood and on the yield moment of the bolts. The purpose of the research was to develop a prediction method for the time...

History of structures has been the theme of three successive IASS (International Association for Shell and Spatial Structures) Symposia held in Istanbul from 1988 to 2000. In the first one the development of the dome as a structural form from antiquity to modern times was the main subject. The second symposium held in 1993 focused on structures hav...

This paper describes a study into the fire behaviour of steel portal frame buildings at elevated temperatures using the finite element programme SAFIR. The finite element analysis carried out in this report is three dimensional and covers different support conditions at the column bases, the presence of axial restraints provided by the end walls, d...

This paper describes post-tensioned timber alternative designs for a six-storey office building in New Zealand. The building has long-span timber-concrete composite floors supported on laminated veneer lumber beams, columns and walls. Lateral loads are resisted with moment-resisting post-tensioned timber frames in one direction and post-tensioned c...

This paper describes the challenges of predicting structural performance in fires, with a view to the past, the present and the future. Despite the huge advances in computational capability for both fire modelling and structural analysis, it remains very difficult to give accurate predictions of structural performance in a single building with a kn...

The choice of the best floor solution has always been a key issue in the design and construction of multi-storey timber buildings. Strict performance requirements such as effective acoustic separation of inter-tenancy floors, thermal mass, fire resistance, limitation of deflection, resistance to vibrations and effective diaphragm action are very ha...

This paper describes numerical modelling of the fire behaviour of two-way reinforced concrete slabs in a multi-storey multi-bay building. The building is square, with three bays in each direction. The concrete slab is supported by a perimeter frame, four internal columns and no internal beams. It is assumed that all nine bays of the concrete slab a...

This preliminary paper is a progress report on an analytical investigation into the implications of explosive spalling on the fire performance of reinforced concrete structural elements and whole structures. This study does not attempt to predict whether spalling will occur. For accurate prediction of the occurrence of spalling a complete and fully...