Robert McKinley Foster

Proposal for Defining a Tall Timber Building

This is the author accepted manuscript. The final version is available from the American Society of Civil Engineers via http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0001615

Super Tall Timber: design research for the next generation of natural structure

This research project aspires to make truly tall timber buildings a reality. Through a combination of theoretical design and physical testing this research demonstrates the viability of timber buildings at much greater heights than has previously been possible. By pushing the limits of theoretical designs into the realms of the supertall, sometimes beyond that which is feasible using current materials and construction technologies, this research also sets out the requirements for the next generation of engineered plant-based materials. The research is a collaboration between academics, practising architects and practising structural engineers. The approach is research through design, and design through research. Timber towers are designed well beyond existing heights, and analysed to understand how they stand up and which areas are most critical for further research. By bringing highly regarded architectural and structural designers together with the research capabilities of a leading university, this project creates a precedent-setting model for interdisciplinary engagement within and between the design and research communities. By coupling exemplary design in timber with a university’s research capacity, the project represents a real opportunity for transformational change in the design of tall timber buildings. Essential details and connections are determined and ‘unknowns’ with respect to material and structural performance are identified. A programme of testing to investigate these unknowns and validate the design approaches is carried out at the university. Outcomes of the test programme and new insights are fed back into the design process. The results show that tall timber towers are feasible, with substantial but surmountable questions outstanding. By providing thought provoking yet credible solutions for the design of tall timber buildings and exceeding current limits, the project can inspire the design community to think beyond the status quo and embrace the possibilities offered by timber construction.

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.

Modified Push-Off Testing of an Inclined Shear Plane in Reinforced Concrete Strengthened with CFRP Fabric

AbstractThis study reports the findings of an experimental investigation into the behavior of an inclined shear plane in reinforced concrete, such as a diagonal crack in the web of a beam, strengthened with externally bonded carbon fiber–reinforced polymer (CFRP) fabric. A modified push-off test of novel geometry was developed for this study. This test generates a diagonal failure plane subject to combined shear and tension. Both unwrapped and wrapped tests were conducted, allowing the load sharing and load-displacement behavior of the reinforced concrete, and the reinforced concrete with externally bonded CFRP fabric, to be investigated. Fully wrapped and U-wrapped CFRP fabric configurations were tested. Results indicate that for the arrangement tested, concrete, steel, and CFRP contributions to resistance are not independent, and that effective anchorage lengths given in the United Kingdom and United States guidance for U-wrapped CFRP may not be adequate in some cases.

Research data supporting 'Penellum, et al. Relationship of structure and stiffness in laminated bamboo composites, Construction and Building Materials, 2018'

Raw data in excel sheets presenting bending siffness and fibre volume fraction of processed engineered bamboo beams.

Research Data Supporting "Experimental investigation of reinforced concrete T-beams strengthened in shear with externally bonded CFRP sheets"

Force-displacement, shear stress-normalised displacement and CFRP strain gauge data are provided.