Julie Bregulla

Modelling of Non-metallic Timber Connections at Elevated Temperatures

Models estimating the slip modulus and the load capacity, including temperature dependent effects, of non-metallic timber connections are presented. Previous studies, including the work of Thomson, have shown that ‘Glass Fibre Reinforced Polymer’ (GFRP) rods are suitable connectors for timber and that ‘Densified Veneer Wood’ (DVW) functions effectively as a flitch plate material. Thomson’s model predicting the slip modulus of the connection with GFRP rods and DVW plates is revised in this paper. The revised model is used to predict the slip modulus and the failure load at room temperature and elevated temperatures. The latter is achieved by predicting local temperatures in the connection and taking corresponding reduced material properties into account.

Lateral-load resistance of cross-laminated timber shear walls

Cross-laminated timber shear wall systems are used as a lateral load resisting system in multistory timber buildings. Walls at each level typically bear directly on the floor panels below and are connected by nailed steel brackets. Design guidance for the lateral-load resistance of such systems is not well established and design approaches vary among practitioners. Two cross-laminated two-story timber shear wall systems are tested under vertical and lateral load, along with pullout tests on individual steel connectors. Comprehensive kinematic behavior is obtained from a combination of discrete transducers and continuous field displacements along the base of the walls, obtained by digital image correlation, giving a measure of the length of wall in contact with the floor below. Existing design approaches are evaluated. A new offset-yield criterion based on acceptable permanent deformations is proposed. A lower bound plastic distribution of stresses, reflecting yielding of all connectors in tension and cross-grain crushing of the floor panel, is found to most accurately reflect the observed behavior.

14 – Fire performance of natural fibre composites in construction

This chapter begins by describing the thermal decomposition of constituents (polymer and natural fibre reinforcement) of natural fibre composites (NFCs). It then investigates the fire performance of NFCs, including reaction to fire testing, heat transfer of NFC building materials, thermal decomposition and fire resistance of NFCs. The chapter also includes a review of the modelling fire performance of NFCs, its residual mechanical properties and its thermoroperties.

Stiffness Modelling of Non-metallic Timber Connections with Pultruded Dowels

Previous studies have shown that double shear timber connections with glass fibre reinforced polymer dowels are a viable alternative to metallic timber connections. Different models have been proposed for predicting the load capacity of the connection. A model which accurately predicts stiffness for connections of this type is, however, not yet published. This paper discusses a two dimensional linear finite element model that predicts the slip modulus of non-metallic timber connections made with pultruded dowels. The model is compared to experimental results and it is concluded that the two dimensional model is accurate.

Ultra-thin topping upgrades for improved serviceability performance

Timber floors can be refurbished by connecting a concrete topping to the timber joists; stiffening the floor and reducing serviceability problems, including vibration. Research to date has focused on upgrade solutions with relatively thick toppings (40mm or greater). This paper presents a novel, ultra-thin topping solution where the topping is placed at a thickness of 20mm or less. Advantages of the solution include: reducing the mass added to the existing structure and minimising the change in floor to ceiling height whilst delivering a significant increase in floor stiffness. This paper reports the findings from the serviceability testing of an upgraded, full scale timber floor. Measurements prior to and after the upgrade are compared, including: elastic testing under static loads, vibration testing and short-term bending tests. The paper also compares the results with simple analytical approaches and design limits prescribed in Eurocode 5 Part 1-1.