Currently there is a worldwide renaissance in timber building design. At the University of Canterbury, new structural systems for commercial multistorey timber buildings have been under development since 2005. These systems incorporate large timber sections connected by high strength post-tensioning tendons, and timber-concrete composite floor systems, and aim to compete with existing structural systems in terms of cost, constructability, operational and seismic performance. The development of post-tensioned timber systems has created a need for improved lateral force design approaches for timber buildings. Current code provisions for seismic design are based on the strength of the structure, and do not adequately account for its deformation. Because timber buildings are often governed by deflection, rather than strength, this can lead to the exceedence of design displacement limitations imposed by New Zealand codes. Therefore, accurate modeling approaches which define both the strength and deformation of post-tensioned timber buildings are required. Furthermore, experimental testing is required to verify the accuracy of these models. This thesis focuses on the development and experimental verification of modeling approaches for the lateral force design of post-tensioned timber frame and wall buildings. The experimentation consisted of uni-direcitonal and bi-directional quasi-static earthquake simulation on a two-thirds scale, two-storey post-tensioned timber frame and wall building with timber-concrete composite floors. The building was subjected to lateral drifts of up to 3% and demonstrated excellent seismic performance, exhibiting little damage. The building was instrumented and analyzed, providing data for the calibration of analytical and numerical models. Analytical and numerical models were developed for frame, wall and floor systems that account for significant deformation components. The models predicted the strength of the structural systems for a given design performance level. The static responses predicted by the models were compared with both experimental data and finite element models to evaluate their accuracy. The frame, wall and floor models were then incorporated into an existing lateral force design procedure known as displacement-based design and used to design several frame and wall structural systems. Predictions of key engineering demand parameters, such as displacement, drift, interstorey shear, interstorey moment and floor accelerations, were compared with the results of dynamic time-history analysis. It was concluded that the numerical and analytical models, presented in this thesis, are a sound basis for determining the lateral response of post-tensioned timber buildings. However, future research is required to further verify and improve these prediction models.

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 energy dissipaters. The extensive experimental testing on post-tensioned timber building systems has proved a remarkable lateral response of the proposed solutions. A wide number of post-tensioned timber subassemblies, including beam-column connections, single or coupled walls and column-foundation connections, have been analysed in static or quasi-static tests. This contribution presents the results of the first dynamic tests carried out with a shake-table. Model frame buildings (3-storey and 5-storey) on one-quarter scale were tested on the shake-table to quantify the response of post-tensioned timber frames during real-time earthquake loading. Equivalent viscous damping values were computed for post-tensioned timber frames in order to properly predict their response using numerical models. The dynamic tests were then complemented with quasi-static push and pull tests performed to a 3-storey post-tensioned timber frame. Numerical models were included to compare empirical estimations versus dynamic and quasi-static experimental results. Different techniques to model the dynamic behaviour of post-tensioned timber frames were explored. A sensitivity analysis of alternative damping models and an examination of the influence of designer choices for the post-tensioning force and utilization of column armouring were made. The design procedure for post-tensioned timber frames was summarized and it was applied to two examples. Inter-storey drift, base shear and overturning moments were compared between numerical modelling and predicted/targeted design values.

Post-tensioned timber frames have recently been undergoing heavy research and development at the University of Canterbury. The recently developed post-tensioned timber system utilises engineering wood products such as Laminated Veneer Lumber (LVL) and glue laminated timber (Glulam), which are formed into box sections and post-tensioned with high strength steel tendons made from stranded steel wire or solid steel bars. The post-tensioning serves to counteract some of the bending actions imposed on the timber beam from loading through a variety of mechanisms. Previous research has focused on the seismic performance and gravity frame performance of post-tensioned timber, both of which yielded promising results. There is however a commonly perceived increase in fire risk with timber building, particularly multi-storey timber buildings, and the fire performance of post-tensioned timber had not previously been investigated. Therefore, the focus of this research was to investigate the fire performance of post-tensioned timber beams. This was completed through a series of full-scale furnace tests, and the development of a fire resistance design method. Three 4.36m span post-tensioned timber beams were exposed to the ISO 834 standard fire. Each of the test beams were glued box beams made from 63mm LVL and were of varying external dimensions. Each beam was intended to demonstrate a specific failure mechanism at approximately 60 minutes of fire exposure. The failure mechanisms demonstrated were a shear failure in the lower corner of due to corner rounding, and a combined bending and compression failure at the end of the beam. These failure mechanisms are unique to post-tensioned timber in fire. The results of the experimental testing were used to validate and refine the proposed fire resistance calculation. Also tested during the full-scale testing were five different forms of anchorage fire protection. These were tested as a secondary objective, but useful thermal data was collected. Through the full-scale testing and the calculation method development it was found that it is important to consider shear during fire design. The post-tensioning increases the bending capacity of a beam but doesn’t affect its shear capacity, therefore when more loading is applied to utilise the increased bending capacity the shear action is increased which leads to shear governing the design in many cases. It is also important to consider shear not only in the webs at the centroid where the shear flow is greatest but also in the lower corners, which can become much thinner than the webs. Without calculation it is not possible to determine where the shear stress will be greatest and therefore both the web and the lower corners need to be checked. It was also found that as the timber section chars on three sides the post-tensioning eccentricity increases which can lead to the moment at the end of the beam becoming critical. Other failure mechanisms which need to be checked include, combined bending and compression at mid span, and tension in the bottom most fibre at mid span. It was found that the proposed calculation method, when used with a char rate of 0.72mm/min and an additional allowance of 7mm for temperature-affected timber beneath the char layer, provided good predictions of the failure times for the full-scale experiments.

A new structural system for multi-storey timber buildings has been developed over the last seven years at the University of Canterbury. The system incorporates large timber structural frames, whereby semi-rigid beam-column connections are created using post-tensioning steel tendons. This system can create large open floor plans required for office and commercial buildings. Several material properties of the engineered timber used were determined based on small-scale experimental testing. Full-scale testing of beams, connections and frames resulted in a more comprehensive understanding of the behaviour of such systems. Numerical, analytical and framework models also led to the development of design equations and procedures which were validated with the acquired experimental data.

This research investigated the fire performance of unprotected timber floors, focussing on composite joist floors, composite box floors and timber-concrete composite floors. The study of these floors was conducted using the finite element software ABAQUS using a thermo-stress analysis in three dimensions, and with experimental fire tests of floor assemblies. The major goal of this research was to develop a simplified design approach for timber floors, validated against the numerical and experimental work. Four furnace tests were conducted on unprotected timber floor systems in the full-scale furnace at the BRANZ facilities in New Zealand. The tested floors were one-way strip floors with pinned support conditions exposed to the ISO 834 standard fire for varying durations of 30 – 105 minutes. The floors were loaded under standard office loading conditions of 3.0kPa live and 1.0kPa superimposed dead loading. The charring rates of the LVL timber members were found to range from 0.66 – 0.86 mm/min across all specimens. When designed to resist a similar load level both the composite joist and box floor types had a similar response to the fire loads, however the joist floors exhibited increased upward burning through the beam members in the latter stages of testing which may contribute to earlier failure times for smaller floor geometries. A sequentially coupled thermal-stress analysis was conducted to determine the effects of a fire on floor assemblies under load. Firstly a thermal analysis was performed to determine the temperature profile of the floor assemblies for the duration of modelling, and then a stress analysis was performed using the temperature profile as input into the structural model. With regards to the thermal modelling, a proposed set of effective values was used to account for the mass transfer processes occurring in the timber. The thermal modelling predicted the charring damage of the floors tested in the experiments to within a few millimetres of precision, and the simplified assumptions made in relation to fire inputs, boundary conditions, mesh refinement and effective material parameters were accurate to the desired level of precision. A sensitivity study was conducted comparing different mesh sizes, time step sizes, material model approaches and software suites to determine any shortfalls which may be encountered in the analysis. It was found that a material model adopting a latent heat approach was the most adequate for modelling timber in fires using these effective values, and mesh sizes of up to 6 mm produced relatively precise results. The structural modelling predicted the displacement response and failure times of the floors to within 20% of the experimental data, and the simplified assumptions made in relation to fire inputs, boundary conditions, mesh refinement and effective material properties were once again accurate to the desired level of precision. A modification to the reduction in tension strength at elevated temperatures was proposed to better predict the observed behaviour. A sensitivity study concluded that the material model definition plays a vital role in the output of the modelling. Non-standard fire exposures were also modelled for completeness. A simplified design method to estimate the fire resistance of unprotected floor assemblies was also developed. The method uses a bi-linear charring rate the assumption of a zero strength layer in the timber. The method was compared to the experimental data from this research and others around the world. The results were also compared to other charring rate methodologies from around the world.

A research project at Linnaeus University focuses on optimizing theadhesives joints between wood and glass, with the aim of obtain stiffcomponents that can act as a load and stabilizing elements and still betransparent. But there is, however, still a lack of knowledge regarding theadhesive materials which need to be further investigated. This thesis focused on testing six different adhesives in relaxation and todetermine the viscosity (η) and modulus of elastic (MOE, E). Viscosity andMOE are then used in combination in a standard linear solid model (SLS)describing the viscoelasticity mathematically. Figures and tables are used topresent the results and the evaluation. The so determined parameters can beused in e.g. finite element models for the design of load bearing timber glasscomposites.

Ecological restoration is the practice of assisting the recovery of a degraded, damaged or destroyed ecosystem. The aim of this study was to analyse the effects of two different restoration techniques on instream bryophyte abundance, species richness and diversity as well as community composition, in streams channelized for timber-floating. Instream bryophytes were collected from 10 tributaries of the Vindel River in boreal northern Sweden, from five stream reaches each of channelized reaches, which had not been restored; reaches restored in the early 2000s, using best-practice techniques; and reaches restored in the early 2000s and then re-restored in 2010 using the new “demonstration” techniques. A multitude of environmental variables were also measured at the sites. Bryophyte abundance was lower in demonstration restored sites than unrestored or best-practice restored sites but no significant difference was found in bryophyte species richness, diversity or species composition. Environmental variables correlated with bryophyte abundance, species richness, diversity and composition largely reflected effects of restoration, and probably the disturbance associated with restoration. Small sediment grain sizes also had a negative effect on species richness. Other environmental variables that influenced bryophyte species composition were the large-scale factors of latitude, longitude and elevation and reach-scale factors of potassium concentration and light absorbance. It is not yet possible to fully evaluate the effectiveness, in terms of bryophyte response, of the new demonstration restoration compared with best-practice since the recovery time between them differs and has not been sufficient. Long-term monitoring of the effects of restoration is needed in order to better evaluate success.

In this thesis, the behaviour of glued laminated timber combined with hardwood and softwood lamallae is investigated. The influence of hardwood in the tension and compression zone, in terms of strength and stiffness is evaluated.The basis of evaluation consists of determining the behaviour of beams with various combinations of hardwood solely in the tension zone along with beams with hardwood in the tension and compression zone. The influence of different amount of hardwood for both cases is studied my means of experimental and analytical methods.Experimental data attained by performing bending tests are evaluated for different combinations made from spruce and oak. By comparing the experimental and analytical data an increase in the strength and stiffness in various combinations is observed and potrayed which varies based on different wood species.

The motivation for this research was to apply methods of vibrations testing in order to determine axial loads in the pin-ended truss members of the Breeding Bam. This method of vibrations testing was necessary in order to determine the in-situ axial loads of the truss members in the bam. Other common methods, such as strain gauges, were not useful for this application. This is because strain gauges can only detect changes in strain and therefore only changes in load. However due to the size and weight of the roof at the Breeding Bam, significant axial loads are produced in the truss members. This in-situ axial load due to the dead load of the roof is a significant portion of any additional loading and cannot be ignored. The ultimate goal of determining the axial loads in the truss members was to develop a model for the roof structure of the bam that accurately predicts axial loads in the truss members over a range of loading conditions. Developing such a model was important in order to make a structural assessment ofthe Breeding Bam's roof structure. In order to determine the axial loads in the truss members, acceleration time histories of the individual truss members were collected using wireless accelerometers provided by MicroStrain of Williston, Vermont. Using the Fourier transform, power spectral densities were produced from the raw acceleration time histories. It was from these plots that the resonant frequencies of the truss members were determined. Knowing the resonant frequencies for a member and the beam vibration equation developed for pin-ended members, the axial load of the truss member were calculated. This process was done for each wrought iron truss member for three separate loading conditions. The purpose of this was to provide enough experimental data so that it could be compared with predictions of several proposed frame models of the bam's roof structure. Ultimately a model was chosen that best predicted the axial loads in the truss members based upon the three loading combinations tested. Using this frame model, an assessment of the bam's roof structure could be made.

Master of Science / Department of Architectural Engineering / Kimberly Waggle Kramer / Main lateral force resisting systems (MLFRS) in timber buildings consist of two components: diaphragms and shear walls. Diaphragms are used to collect the shear induced by the lateral force at each of the levels. The shear is transferred from the diaphragms to the shear walls via plywood sheathing and connections. The shear walls transfer shear to the sill plate via plywood sheathing and then into the foundation via anchors. Two approaches for designing shear wall are: the segmented shear wall approach and the perforated shear wall approach. The segmented shear wall approach uses only full height segments to resist shear; each individual segment must be designed to resist the shear and overturning force induced by the lateral load. The perforated shear wall approach uses both full height segments and segments around openings to resist shear; the wall as a whole is used to resist shear and overturning forces induced by the lateral load. This report examines one-, two-, and three-story timber buildings located in three different wind regions: a) 115 mph, b) 140 mph, and c) 160 mph. This report presents the design process for the MLFRS components and a comparison of the designs for each of the buildings. The purpose of this report is to determine how the design changes depending on the magnitude of the lateral load, the height of the building, and the approach used to design the shear walls.