Development and optimisation of low-carbon, affordable, medium-rise modular structural system using innovative connections

Sustainable building design and construction Prefabricated construction Australia

Due to the increasing rates of urbanisation and the ever growing urban population, it is inferable that the demand on multi-story construction industry will continue to increase. In Australia, having an urban population of approximately 21 million, equivalent to 90% of the total population, the construction industry is a key driver and contributes to approximately 7.8% of the country’s GDP in value added terms, where issues regarding quality control, reduced workplace productivity, onsite safety, skilled labour shortages, rising costs and environmental impacts are of great concern.

Aligned with Industry 4.0, the new era for automation in construction promotes on shifting from traditional on-site construction and design for prefabrication and modularization. This may provide the best set of tailored solutions to address the above-mentioned issues in a time and cost efficient manner. Particularly, modular construction would deliver significant reductions in embodied energy as well as operational energy through optimal use of materials, labour and technology.

Although the use of prefabricated volumetric components such as fully-completed modules have been successfully introduced to low-rise construction, its application beyond low-rise forms is still a challenge and yet to achieve a fully-modular status. The identified limitations in utilising modules for such cases are the lack of high-performance connections that provide efficient horizontal and vertical load transfer and lack of guidelines addressing overall design, handling of modules and erection of modular buildings. Further, very few research works have looked into the extreme load performance of modular buildings and have satisfactorily captured the behaviour and influence of individual modules and their connections on overall system-level building response.

This study aims to address this urgent need by conducting a comprehensive study on performance requirement of modular buildings under service/extreme loads and accordingly develop an innovative structural connections for modular connection. This report presents the outcomes of this study, which was done through a multi-institutional collaborative research project between Swinburne University of Technology, Melbourne University and the industry partners AECOM, Bluescope, Multiplex, Hassell and the Victorian Building Authority (VBA).

In this report, a systematic study is presented that covers the behaviour of diaphragms in multi-story modular buildings and the essential characteristics required for inter-module connections. It is expected that inter-module connectivity should meet structural needs along with satisfying manufacturing and construction requirements. Brief descriptions of existing inter-module connecting systems that are available in both literature and the public domain including a critical review of those connections against the identified performance requirements are also presented.

An entirely new concepts for inter-module connectivity is then proposed. A preliminary assessment on overall functionality and structural conformance via simplified kinematic and finite element models is performed. Model development and kinematic checks are done using the software AutoDesk Inventor, whereas preliminary finite element analyses are undertaken using the software ANSYS.

Upon having verified the functionality of the prototype connector and its expected structural behaviour, it is then opted for experimental verification and proof of concept validation. Therefore, a series of static load tests are planned for determining the factor of safety in design and to evaluate the actual load bearing capacities and deformability when under service and ultimate loads. The loading represents the forces generated in the connector when it serves as part of horizontal and vertical load resisting systems within a modular building. Finally, the study is extended to investigate the dynamic loads experienced by modular units during transportation.

The outcomes of this comprehensive study are expected to provide quantum improvements on the current modular construction industry through fast on-site assembly, in‐life adaptation to service/extreme loads, post‐life disassembly, and affordability. This will assist in the future development and application of fully-modular superstructure construction systems for multi-story modular buildings.

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