The reduction in on-site construction work has many benefits with respect to time, quality, productivity, safety, cost and environmental impact, and can be achieved through off-site manufacturing of building components. Such building components range from linear, planar or volumetric in form and once manufactured are transported to site for assembly. This method of prefabricated or modularized construction enables the use of automated systems in construction which further maximizes benefits and falls in line with the goals of industry 4.0 initiative.
The use of linear (beams, columns, ties, etc.) and/or planar (trusses, slabs, panels, etc.) prefabricated components for mid- to high-rise construction has been in practice for quite a while with examples such as the T30 hotel building in Changsha, China (2012) and the World Trade Centre Twin Towers in New York, USA (1973). However, the use of volumetric building units is a relatively new form of construction and there has seen much development in the past few years for application to mid- to high-rise buildings. Examples for such forms include the LaTrobe Tower in Melbourne, Australia (2016) and the Apex House building in London, UK (2017). This form of construction is also commonly referred to as modular building construction.
Although these examples exist, none avert the reliance on conventionally-built support structures to provide lateral strength, stiffness and overall stability. Therefore, none can be called a complete modular building system, where on-site work is reduced simply to foundation, module assembly and module-to-module interface finishing/treatment as required. This setback is primarily due to the difficulties in achieving efficient lateral load resistance and the incapability to provide high-performance inter-module connectivity.
Volumetric building units or modules, are the result of spatial modularization of buildings. The modules require to have a self-stable structural system and can either be bear with the structural system alone or be fully complete (finishing, fitting and furnishing included). These modules typically transfer vertical loads via continuous bearing onto each other through braced stud walls or via selective placement of columns. The transfer of lateral loads, on the other hand, inevitably requires the use of bracings or the reliance on diaphragm action for economical designs using a strategically placed lateral force resisting system. Much of achieving continuous transfer of these loads depends on the vertical and horizontal inter-connectivity between modules. Hence, this research attempts to solve the issue by developing robust high-performance inter-connectivity of the modules, thereby, achieving efficient overall vertical and lateral load resistance.
When considering current connecting systems for prefab/modular buildings, it is found that most rely on the use of bolted connections for high load transfer between modules vertically and horizontally, which requires risky direct internal/external access and considerable time for alignment and overall assembly. The lack of having integrated components limits mass production of such connections and their scalability to meet strength and size requirements. This project proposes an innovative concept of boltless connection for modular construction that is expected to simultaneously address all these functional issues and has done away with the use of bolted systems. The proposed connection concept is numerically verified through FE simulations and experimentally validated through half-scale axial tension/compression and shear tests. The results are used to simulate the system-level response of multi-story modular buildings constructed with this connection.
For the development of high-performing mechanical connections, the first step was to gather and document best practices with regard to building construction using volumetric modules and perform a critical review on current systems. Having identified limitations and constraints, a list of structural as well as functional performance requirements were identified/prepared. To address the structural performance requirements, a hypothetical generic multi-story building configuration was assumed to be formed by volumetric building units or modules that were of 16m length, 4m width and 4m height. The peripheral frames of the building were selected to provide lateral force resistance and were of the braced frame type. A numerical approach was demonstrated indicating the key influences of connection axial and shear stiffness as well as module stiffness on achieving efficient diaphragm resistance and overall lateral stability. Extreme loading events such as earthquakes were also taken into consideration apart from general loading scenarios for a comprehensive assessment on structural performance requirements for the overall building. The numerical study led towards establishing performance targets which assisted in evaluating the suitability of the proposed inter-module connection concepts. These concepts were proposed to first address the identified set of functional needs (be simple in functionality, be remotely operable, be demountable, be easily scalable, be simple to mass manufacture and be capable of handling tolerances) prior to being assessed for satisfactory structural performance with respect to having adequate strength and stiffness. Mechanical functionality was evaluated through kinematic models and structural performance expectations were established through analytical as well as finite element methods for concept selection and prototyping. Upon successful prototype demonstration, the appropriately scaled model was fabricated and subjected to experimental testing for further characterization, evaluation of conformance with expectations and possible future development of design guidelines.
The proposed innovative boltless connection is simple in functionality, fast in assembly, mass-producible, easily scalable and demountable. Its application in modern construction provides local employment opportunities as well as a large potential for export with direct impact on the local Australian manufacturing economy.
Swinburne University of Technology
Prof Fernando is an internationally recognised fastener expert having worked for more than 20 years in the fastener industry. As R&D, Engineering and Innovations manager at Ajax Engineered Fasteners, he led heavy engineering fastening under an R&D syndicate worth $24M across a 3-year period. His expertise involves bolted joint design, failure analysis, bolt forensics, design and manufacturing of specialised fastening solutions, quality assurance and automation, to name a few. Prof Fernando has authored 22 national and international patents in advanced fastening concepts, some of which are currently in the international markets. He has a large number of publications in the area of fastening technology. Prior to entering the fastener industry, Prof Fernando was a well-recognised expert on Wind Engineering, Industrial Aerodynamics and Thermodynamics. He was the Principal Engineer Building and environmental technology at VIPAC Engineers and Scientists and made many contributions in the area. Prior to that he worked for NASA on STOL aircraft and Space-Station related projects.
Professor Emad is the Dean of Engineering, School of Engineering within the Faculty of Science, Engineering and Technology. Prior to this appointment, he was the Chair of the Department of Civil and Construction Engineering at Swinburne University of Technology. Earlier he was an Associate Professor at Melbourne University and Research Scientist at CSIRO.
Emad is a civil engineer with extensive experience in structural dynamics, residential construction, structural connections, experimental techniques and finite element modelling. His applied research has contributed to the development of several standards and codes of practice. In addition to his teaching and research contributions, he has completed numerous consulting contracts for local and multinational clients.
He is Chair of the Board of the Australian Engineered Fasteners and Anchors Council (AEFAC), Co-Editor of the Australian Journal of Structural Engineering, appointment member of the Victorian Government Building Advisory Council (BAC) and Fellow of Engineers Australia.
Dr Hashemi is a Lecturer of Structural Engineering and the Deputy Director of the Smart Structures Laboratory at Swinburne University of Technology. He holds a Bachelor of Science and Masters of Science from Sharif University of Technology, the highest-ranked technological university in Iran, and a PhD from the University at Buffalo, the State University of New York, USA. His field of research involves the development of knowledge and innovative tools for extreme load performance assessment of complex structures. More specifically, it concentrates on hybrid simulation, where the flexibility and cost-effectiveness of computer simulation are combined with the realism of large-scale experimental testing.
Dr Hashemi’s research experience during the past 8 years has enabled him to make considerable contributions to the advancement of large-scale hybrid simulation and the development of hybrid testing facilities in USA and Australia. He had a leading role in the development of Australia’s first and only 6-DOF hybrid testing facility, known as the Multi-Axis Substructure Testing (MAST) system, at Swinburne. Dr Hashemi won the 2016 Engineers Australia Excellence Award for Innovation, Research and Development (High Commendation) and was awarded the WH Warren Medal 2017 by the Board of the College of Civil Engineers of Engineers Australia for the best paper in the discipline of civil engineering.
Dr Raj Rajeev joined the Department of Civil and Construction Engineering at Swinburne University of Technology (SUT) as a Senior Lecturer in November 2013. Prior to joining SUT, he worked as a research fellow at Monash University from 2009 to 2013. His work at Monash focused in the areas of failure management of pipeline (both onshore and offshore), numerical modelling of pipe-soil interaction, and sensor technology for pipeline monitoring.
He earned his BSc degree with Honors in civil engineering from the University of Peradeniya in Sri Lanka and MSc in Earthquake Engineering from ROSE School, University of Pavia in Italy. Prior to pursuing his PhD at ROSE School, he was a visiting researcher at TNO DIANA B.V in The Netherlands and working on dynamic soil-structure interaction (finite element) modelling of geo-systems. He received his PhD in Earthquake Engineering (Structural) in 2008 under the guidance of Professor Paolo. E. Pinto.
His research interests include earthquake-resistant design and analysis of structures, pipeline engineering, soil-foundation-structure interaction (SFSI), advanced sensor technology and structural reliability and risk analysis. His research projects have been funded by the Australian Research Council, Department of State government Victoria, CRC for Low Carbon Living, Australian Building Codes Board, Italian Civil Protection Agency, European Union, non-profit institutions, and private industry.
Mr Srisangeerthanan Sriskanthan is a PhD student at the Department of Civil and Construction Engineering at Swinburne University of Technology, Hawthorn. He received his BSc Eng Hons Degree (first class) in Civil Engineering with a minor in Structural Engineering from University of Moratuwa, Sri Lanka. His PhD work relates to the development of connections for multi-storey modular buildings under the principal supervision of Dr. Pathmanathan Rajeev and Prof. Emad Gad.