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.
Project contact is Luca Sorelli at Université Laval
This project aims to develop a new prefabricated wood / concrete floor system that is innovative and competitive in multi-storey wood buildings. The design of the floor will be carried out through a multidisciplinary approach that considers the composite action of the precast floor, the integration of sound insulation, vibrations, the weight of the structure, construction time and environmental impact. Among other things, the construction method and the use of ultra high performance green composite concretes with CLT slabs or GLULAM beams will be considered. The methodology includes digital analysis tools and a new method for the design of mixed structures as well as the life cycle tool. The laboratory proof of concept will assess the performance of the optimized floor system and compare it to existing floors.
Project contact is Luca Sorelli at Université Laval
This project aims to develop a new precast wood / concrete floor system that can push the span limits in multi-storey wood buildings. The multidisciplinary methodology includes a finite element analysis technique using the “DDuctileTCS” software developed at CIRCERB, shear tests on connections, bending tests of the composite beam and an extension of technical standards for the design of composite structures. This project will develop solutions to optimize the composite action and vibration of long-span precast and mixed floors. The methodology consists of: (i) analysis of systems and optimization of shapes by numerical finite element techniques; (ii) connection shear tests; (iii) proof of concept on a prototype beam in the laboratory.
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.
This paper deals with aspects of force- and displacement-based design of multistorey cross-laminated timber (CLT) structures. A method to determine the behavior factors for timber structures based on nonlinear static analyses will be discussed. Different types of analysis models are considered. Results of experimental investigations on connections and CLT wall elements will be presented as a basis for numerical simulations.
This paper describes numerical modelling to predict the fire resistance of engineered timber floor systems. The floor systems under investigation are timber composite floors (various timber joist and box floor cross sections), and timber-concrete composite floors. 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 is also being undertaken to calibrate and validate the models, with a number of full scale tests to determine the failure mechanisms for each floor type and assess fire damage to the respective system components. The final outcome of this research will be simplified design methods for calculating the fire resistance of a wide range of engineered timber floor systems.
Long-span timber-concrete composite (TCC) floor systems have the potential to address the design challenges for conventional wooden floors in residential multi-storey timber frame buildings. The aim of this paper is to develop a design approach for long-span timber-concrete composite floor system of 6–9 m. A framework based on value-driven design approach has been developed for integration of results from graphical multi-objective optimisation, spreadsheet-based analysis, structural static and dynamic finite element analysis, and multi-criteria decision making. To verify the developed framework, a residential five-storey timber frame building as a case study has been studied. Optimal design includes optimised thickness of the concrete and optimised smeared stiffness of connectors for three different comfort classes A to C in descending order. TCC floor with span length 7.3 [m] belonging to comfort class A and TCC floor with span length 9.0 [m] belonging to comfort class C has been chosen as optimal solutions. The results indicate that proposed and innovative design approach is a promising tool for developers, architects and structural engineers when designing optimal long-span timber-concrete composite floor system.
This document reports the outcome of the seismic test on the TUGraz building, the fourth in a
total of four buildings included in the TIMBER BUILDINGS Project. This building is a cross
laminated system (CTL). The goal of the tests was to assess the seismic performance of the
building, panel elements and steel connectors, defined in terms of relative displacements and
hold-down forces. This report presents the results of the experimental tests carried out in the LNEC 3D shaking table on a cross laminated system (CTL). The tests were carried out on February 20 and 21, 2013 on a three storey real scale building.
This document reports the outcome of the seismic test on the LegnoCase building, the second in a total of four buildings included in the TIMBER BUILDINGS Project. This building is a platform frame system with sheathing assembled by means of OSB panels (PF-OSB). The goal of the tests was to assess the seismic performance of the building, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.
This report presents the results of the experimental tests carried out in the LNEC 3D shaking table on a platform frame system (PSF) with sheathing assembled by means of OSB panels (PF-OSB) as part of the SERIES Project on multi-storey timber buildings. This project is coordinated by the University of Trento and involves the University of Minho and the Graz University of Technology, at LNEC, in Lisbon. The tests were carried out on June 25, 26, and 27, 2012 on a three storey real scale building.