This thesis studies the behaviour of diaphragms in multi-storey timber buildings by providing methods for the estimation of the diaphragm force demand, developing an Equivalent Truss Method for the analysis of timber diaphragms, and experimentally investigating the effects of displacement incompatibilities between the diaphragm and the lateral load resisting system and developing methods for their mitigation.
Although shortcomings in the estimation of force demand, and in the analysis and design of concrete floor diaphragms have already been partially addressed by other researchers, the behaviour of diaphragms in modern multi-storey timber buildings in general, and in low damage Pres-Lam buildings (consisting of post-tensioned timber members) in particular is still unknown.
The analysis of light timber framing and massive timber diaphragms can be successfully analysed with an Equivalent Truss Method, which is calibrated by accounting for the panel shear and fastener stiffnesses. Finally, displacement incompatibilities in frame and wall structures can be accommodated by the flexibilities of the diaphragm panels and relative connections. A design recommendations chapter summarizes all findings and allows a designer to estimate diaphragm forces, to analyse the force path in timber diaphragms and to detail the connections to allow for displacement incompatibilities in multi-storey timber buildings.
New Zealand Society for Earthquake Engineering Conference
April 10-12, 2015, Rotorua, New Zealand
This paper discusses the design of timber diaphragms, in response to the growing interest in multi-storey commercial timber structures, and the lack of guidance or regulations regarding the seismic design of timber diaphragms.
Proper performance of floor diaphragms is required to transfer all lateral loads to the vertical systems that resist them, but design for earthquake loads can be more complex than design for wind loads. This paper confirms that the seismic design of a diaphragm is intimately linked to the seismic design of the whole building. Diaphragm failure, even if restricted to a limited diaphragm portion, can compromise the behaviour of the whole building. It is therefore necessary to design and detail diaphragms for all possible load paths and to evaluate their influence on the load distribution within the rest of the structure. It is strongly recommended that timber diaphragms be designed as elastic elements, by applying dynamic amplification and overstrength factors derived from the lateral load resisting system.
This paper shows that some current design recommendations for plywood sheathing on light timber framing can be applied to massive wood diaphragms, but for more complex floor geometries an equivalent truss method is suggested. Diaphragm flexibility and displacement incompatibilities between the floor diaphragms and the lateral resisting systems also need to be accounted for.
New Zealand Society for Earthquake Engineering Conference
April 26-28, 2013, Wellington, New Zealand
This paper describes options for seismic design of pre-fabricated timber core-wall
systems, used as stairwells and lift shafts for lateral load resistance in multi-storey timber
buildings. The use of Cross-Laminated Timber (CLT) panels for multi-storey timber buildings is
gaining popularity throughout the world, especially for residential construction. This
paper describes the possible use of CLT core-walls for seismic resistance in open-plan
commercial office buildings in New Zealand. Previous experimental testing at the
University of Canterbury has been done on the in-plane behaviour of single and coupled
Pres-Lam post-tensioned timber walls. However there has been very little research done
on the behaviour of timber walls that are orthogonal to each other and no research into
CLT walls in the post-tensioned Pres-Lam system. This paper describes the proposed test regime and design detailing of two half-scale twostorey CLT stairwells to be tested under a bi-directional quasi-static loading. The test specimens will include a half-flight stair case with landings within the stairwell. The “High seismic option” consists of post-tensioned CLT walls coupled with energy dissipating U-shaped Flexural Plates (UFP) attached between wall panels and square hollow section steel columns at the corner junctions. An alternative “Low seismic option” uses the same post-tensioned CLT panels, with no corner columns or UFPs. The panels will be connected by screws to provide a semi-rigid connection, allowing relative
movement between the panels producing some level of energy dissipation.
This thesis discusses the results of experimental tests on two post-tensioned timber core-walls, tested under bi-directional quasi-static seismic loading. The half-scale two-storey test specimens included a stair with half-flight landings. Multi-storey timber structures are becoming increasingly desirable for architects and building owners due to their aesthetic and environmental benefits. In addition, there is increasing public pressure to have low damage structural systems with minimal business interruption after a moderate to severe seismic event. Timber has been used extensively for low-rise residential structures in the past, but has been utilised much less for multi-storey structures, traditionally limited to residential type building layouts which use light timber framing and include many walls to form a lateral load resisting system. This is undesirable for multi-storey commercial buildings which need large open spaces providing building owners with versatility in their desired floor plan. The use of Cross-Laminated Timber (CLT) panels for multi-storey timber buildings is gaining popularity throughout the world, especially for residential construction. Previous experimental testing has been done on the in-plane behaviour of single and coupled post-tensioned timber walls at the University of Canterbury and elsewhere. However, there has been very little research done on the 3D behaviour of timber walls that are orthogonal to each other and no research to date into post-tensioned CLT walls. The “high seismic option” consisted of full height post-tensioned CLT walls coupled with energy dissipating U-shaped Flexural Plates (UFPs) attached at the vertical joints between coupled wall panels and between wall panels and the steel corner columns. An alternative “low seismic option” consisted of post-tensioned CLT panels connected by screws, to provide a semi-rigid connection, allowing relative movement between the panels, producing some level of frictional energy dissipation.
This paper related to elimination of the deficiencies. The behaviour of multi-storey buildings braced with cores and CLT shear walls is examined based on numerical analyses. Two procedure for calibrating numerical analysis models are proposed using information from Eurocode 5  and specific experimental test data. This includes calibration of parameters that characterise connections between CLT panels and other CLT panels, building cores and shear walls. The aim is to make the characterizations of behaviours of connections that reflect how those connections perform within complete multi-storey superstructures, rather than in isolation or as parts of substructures. The earthquake action for cases studied was according to Eurocode 8  and using the appropriate behaviour factor (q factor). Results of analyses of entire buildings are presented in terms of principal elastic periods, base shear and up-lift forces. Discussion addresses key issues associated with behaviour of such systems and modelling them. Obtained results permit creation of appropriate guidelines and rules for design of the aforementioned types of hybrid buildings incorporating CLT wall panels.
Cross Laminated Timber (CLT) structures are nowadays increasingly used worldwide and mostly in Europe where the system originated. However, in spite of this diffusion which led to the construction of a great number of multi-storey buildings all over Europe, still Eurocodes are almost completely missing provisions for CLT designers, especially regarding the seismic design. Nevertheless, Eurocode 8 requires in most cases, due to the regularity criteria being not fulfilled for most of the buildings, the use of the modal response spectrum analysis method, i.e. the linear dynamic analysis. This method requires the correct estimation of the lateral stiffness of the building in order to accurately calculate the design seismic forces in the building, which may be significantly underestimated or overestimated depending on the size of the building and the shape of the design spectrum. This can be done by modelling each connection with different methods that are often based on available test results, which are not easily accessible by a practicing engineer. This paper provides a design approach for dynamic linear modelling of CLT structures using SAP 2000. Equations are proposed based on available design codes and literature references, and used to design a 3-storey case study building. Further provisions for the seismic design of CLT buildings which are not included in Eurocode 8 are also given. Finally, the proposed design model is also compared with the results of the shaking table tests conducted in 2006 in Japan by CNR-IVALSA on a three-storey CLT building.
Figure 1 shows a floor plan and elevation along with the preliminary shear wall locations for a sixstorey wood-frame building. It is assumed some preliminary calculations have been provided to determine the approximate length of wall required to resist the lateral seismic loads.
If the preliminary design could not meet the drift limit requirement using the base shear obtained based on the actual period, the shear walls should be re-designed until the drift limit requirement is satisfied.
Second European Conference on Earthquake Engineering and Seismology
August 25-29, 2014, Istanbul, Turkey
In the past, while wood as a natural building material was preferred for only housing construction, today, engineered wood products are used as structural elements even in many different projects such as, schools, airport terminals, stadiums or indoor sport centres and finally in multi-storey houses nowadays. On the other hand, the sustainability is becoming a key focus. Engineered wood products are increasingly used for earthquake resistance as well as natural insulation and sustainable design. Recent studies indicate that the earthquake resistant design through engineered wood products is achievable and affordable. The seismic design of structures typically depends on the ductility of members and connections. The innovative design techniques with wooden composites ensure that the building is functional after a major earthquake event. Within the scope of this study, the earthquake resistant design approaches and experimental results of New Zealand, Canada and Italy are addressed for multi-storey wooden/wooden-hybrid structural systems. Member and connection types, posttensioning effectiveness, floor systems, sustainability and constructability will be focused.
This paper discusses the impact of the natural frequency of multi-storey timber structures, focusing on force-based seismic design. Simplified approaches to determine the frequency of light-frame and cross-laminated timber structures are investigated. How stiffness parameters for simple two-dimensional analysis models can be derived from the different contributions of deformation...