Modular and Offsite Construction (MOC) Summit Proceedings
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Serviceability Performance of Timber Concrete Composite Floors
Get PDFThere is much potential for engineered wood products to be used beyond low-rise residential construction when incorporating the notion of hybrid systems like timber-concrete-composites (TCC). TCC systems are comprised of a timber element connected to a concrete slab through a shear connection. By combining the complimentary properties of timber and concrete, the performance of timber floors can be enhanced, including bending stiffness, load-bearing capacity, dynamic response, airborne sound transmission, structural fire rating, and thermal mass. A large number of T-beam TCC systems existed for decades; however, the growing availability of panel-type products in North America offers designers greater versatility in terms of structural and building physics performance. While stiffness and strength design of TCC systems is straight-forward, there is little design guidance available in terms of vibration and long-term performance. The bending, vibration and long-term performance for a range of TCC systems in several EWPs were validated on small-scale shear tests, floor panels subjected to serviceability loads for 2.5 years, and subsequent full-size bending tests. The tests confirmed that calculations according to the ?-method can predict the basic stiffness and dynamic properties of TCC floors within a reasonable degree of accuracy
Mass Timber Productivity- the Significance of Reduction in Non-Value Add Activities during On-Site Installation Sequence.
Get PDFThe recent uptake of Mass Timber (M.T.), a prefabricated timber panelised form of construction, provides a potential sustainable resource to facilitate improved productivity outcomes to the construction industry. However, in Australia as well as U.S. and Canada, M.T. is in its infancy and there is a lack of empirical information available to industry. This consequently has resulted in reluctance by contractors and professionals to uptake this new innovative system. The aim of this paper is to undertake a comprehensive review of the on-site productivity outcomes. A quantitative Case Study approach was implemented by way of time-lapse digital video recording of three M.T. multi-storey buildings located in NSW, Australia. Crane cycles of the installation of the M.T. prefabricated panels were found to be the most representative and repeatable process and as a consequence were used to measure the M.T. productivity. Discussion is provided on potential areas of process and consequential productivity improvement. The M.T. crane cycles productivity at an Activity Level compared to M.T. productivity at Project Level revealed large differential between the two levels. The quantum of Non-Value Add activities was found to be a significant factor in the overall Project Level productivity outcome. This review paper undertakes a review of the outcomes of the case studies on the M.T. installation on three multi-storey buildings, the factors found that affected the resultant on-site construction productivity and its resultant beneficial implications to the construction industry
The Legacies of Manufacturing and Factories of Industrialised Construction
Get PDFThe term ‘industrialised construction’ carries the promise of an industry transformed, an industry driven by improved processes and higher quality products. One of the more obvious differences between industrialised construction and traditional construction is the factory. Yet it is often undervalued as a secondary consideration to the seemingly more important factors of speed, efficiency and economic rationalisation. This paper offers a reconsideration of the history of the factory as a critical feature in shaping contemporary sites of production in the construction industry. While the manufacturing mega-factories of today continue to develop at a rapid rate, their composition has been shaped by all three previous industrial revolutions and the current fourth. Drawing on the legacies of mechanisation, mass production and automation, today’s factory is informed by ideas of lean and agile production, and the connected factory forecast by Industry 4.0 looks towards the internet, cloud and IoT in visions of the future. By charting the evolution of the preceding three phases of industry in relation to key architectural developments of the factory, this paper reflects upon which aspects of these earlier chapters of manufacturing have affected the implementation of Industry 4.0 in the industrialised construction sector. Research in this area has often asked what the production sites of industrialised construction can learn from contemporary manufacturing, such as the automotive, aerospace or technology industries. By contrast, this paper questions the how the potential requirements of industrialised construction might differ from other forms of manufacturing and how this might in turn inform future sites of production in this sector. This paper speculates that a contemporary industrialised construction industry would be wise to re-evaluate the factory as a space specific to construction, distinct from manufacturing origins, in order to better address the broad range of new, or previously under-considered, industry specific requirements
A Case Study for 3D Modeling Process Analysis based on BIM Log File
Get PDFBuilding Information Modeling (BIM) design becomes popular with the growing needs of enhancing construction efficiency. During the design process, 3D Modeling is the foundation of generating and analyzing building information. The modeling tool, Autodesk Revit, automatically creates log files, which can record all design activities. This paper investigates and analyzes the operation data from unstructured temporal Revit log files. These data were recorded when executing the general and external command to build a 3D model of a typical residential two-story building. The objectives of this analysis were to figure out the influence elements of producing a good framing model and to give some suggestions for improving modeling efficiency. In order to extract the useful specific commands, the information in the text journal file was transferred to an excel file, before reading by a data mining tool, RapidMiner. It generated a pie chart to show the repetition amount of modeling activities. Analyzing the reasons of repeating some commands frequently, this paper contributes the possibility to reduce the useless repetition for building a good 3D model
Disproportionate Collapse Mitigation in Tall Mass Timber Buildings
Get PDFTall buildings are a unique type of structure with their own characteristic behaviour. They are most often occupied by a large number of people; therefore, their damage, loss of functionality, or, in worst case scenario, collapse will lead to catastrophic consequences. There are methodologies intended to provide structural integrity or increase structural robustness in tall buildings, thereby making structures resistant to disproportionate collapse, which is characterized by a cascading progression of damage that is not proportionate to the initial failure. Tall buildings are commonly constructed with steel and concrete. As a result, most of the attempts at providing structural integrity are dedicated to mitigating the effect of disproportionate collapse in the steel and concrete members, connections, and their systems. On the other hand, with rising demand for new sustainable buildings in urban areas, tall mass timber buildings have attracted increased attention nationally and internationally. Ease of modularization and offsite construction is one of the greatest advantages of using mass timber in tall building construction in the congested urban areas of major cities. A major challenge facing the engineering community is the lack of research studies regarding the structural robustness required to mitigate the potential of disproportionate collapse. The current study seeks to begin the process of understanding the behaviour of mass timber components and assemblages, and make recommendations regarding their performance and possible means to mitigate the occurrence of disproportionate collapse. These recommendations would lead to safer structural performance in the event of localized damage that has the potential to spread to a disproportionately large part of the structure
Effect of Loading Speed on the Mechanical Properties of Nail Joints
Get PDFWood shear walls are the main lateral load resisting systems in light wood frame buildings to resist the wind and seismic loads. Sheathing to lumber nail connections are regarded as the key components that control the resistance and failure modes of wood shear walls. Considerable experimental tests have been conducted on performance of nail joints or wood shear walls under both static and reversed cyclic loads. However, these tests were usually conducted under different loading speed causing specimen failure in 1 min to an hour. It is unclear how the loading speed will affect the test results of nail joints or wood shear walls. Research on these topics is limited. This paper aims to evaluate the effect of loading speed on the mechanical characteristics of nail joints. 72 specimens have been tested under various loading speeds, ranging from 0.05 mm/s to 0.5 mm/s for monotonic tests and 1.5 mm/s to 15 mm/s for reversed cyclic tests. The range of loading speed was selected based on the total estimated loading time that both monotonic and reversed cyclic tests fail within around 1 min to 10 min. Two groups of nail joints, comprising two common nail sizes and two sheathing thicknesses, were assessed under both monotonic and reversed cyclic loads. From the test results, the effect of loading speed on the mechanical properties of nail joints was determined
Highly Mechanical Performance of Laminated Veneer Lumber Induced by High Voltage Electrostatic Field
Get PDFThe high voltage electrostatic field (HVEF), as a novel technology, was applied in the study to obtain a highly mechanical performance of LVL (laminated veneer lumber) by increasing limiting value of shear failure strength directly affected by bonding strength. The surface property of wood, polymerization extent of PF, bonding interface of wood-to-PF and mechanical properties of LVL were investigated under the HVEF treatment. The results showed that increased free radicals and total surface energy were acquired under the HVEF treatment resulting from more polar groups (?OH, ?CHO) and ions were triggered leading to decreased contact angles identified both for Poplar and Masson specimens. The HVEF provided more reactions among wood-to-UF and more cross linking reaction of PF occurred in the treating step. The tendency of vertical density profile was more extremely steep than the control with max density increased by 24.93% and 30.24% for Poplar and Masson LVL respectively since adhesive aggregated continuously and orderly along bonding interface and permeation depth reduced to around 200 ?m, accounting for improved bonding shear strength, which eventually brought an enhancement on mechanical properties of LVL with horizon shear strength (?and?), modulus of elasticity and static bending strength significantly enhanced by 14.65%, 10.68%, 20.67% and 12.34% for Poplar LVL and that of Masson LVL enhanced by 17.30%, 13.93%, 18.55% and 12.72%. Besides, the delamination ratio was decreased by 49.57% and 58.32% respectively both for Poplar and Masson specimens
Structural Design and Modelling Method for the Post-tensioned CLT Shear Wall Structures
Get PDFThis paper presents the direct displacement-based design (DDD) procedure, structural modelling method, and structural performance calibration for post-tensioned CLT shear wall structures (PT-CLTstrs). Numerical models of the post-tensioned (PT) CLT shear walls were developed and calibrated with the experimental results. Based on the developed shear wall models, parametric analysis were conducted to investigate the lateral performance influencing factors. Then, a DDD procedure was developed and demonstrated by the design examples of a set of 8-, 12-, and 16-storey PT-CLTStrs. The corresponding simplified structural models were developed, and then a series of pushover and time-history dynamic analysis were conducted to calibrate the calculated structural performance objectives with the design targets of the DDD procedure. Finally, the empirical cumulative distribution functions (CDFs) of the maximum inter-storey drift (MaxISDR) were constructed. It is found that when the width of the PT CLT shear walls increases from 1.8 m to 3.0 m, the base shear at the drift of 2.0 % increases by twice accordingly. When the diameter of the PT strand increases from 15.2 mm to 34.6 mm, the base shear at the drift of 2.0 % increases by up to five times. Additionally, the MaxISDR limitation of the PT-CLTStrs is recommended as 2.2 % under the collapse prevention (CP) hazard level. The study results can serve as guidelines for the development of engineering design methods for the PT-CLTStrs
Risks Identification and Allocation in the Supply Chain of Modular Integrated Construction (MiC)
Get PDFModular integrated construction (MiC) is an offsite construction technique which can improve construction quality, the certainty of the project cost, provide value for money and reduce construction time, waste generation, and carbon emissions. However, MiC is associated with a unique business model, engineering, supply chain, and stakeholder composition, resulting in bespoke uncertainties and risks. Prominent among them is the uncertainties and risk events in its linked supply chain segments. However, risks identification and allocation in the MiC supply chain segments is not well-established. This research identified and assessed 28 risk events (REs) across the manufacturing, logistics and on-site assembly segments of the MiC supply chain. A principal component analysis generated 10, 6 and 12 REs within the modular manufacturing, logistics, and on-site assembly segments, respectively. A fuzzy synthetic evaluation (FSE) modeling revealed that the on-site assembly REs are the most critical set of risk events with a criticality index of 5.58, followed by the modular manufacturing risk events (5.28) and logistics risk events (5.08). These rankings and criticality assessment have profound implications for the practice and praxis MiC risks management. It is a source of relevant information to stakeholders and practitioners in understanding the MiC supply chain risk events and may prioritize the riskiest events to improve the performance of MiC projects. Again, the assessed REs contributes to the checklists of MiC risk events and may form the basis for future studies on the risk of MiC. Future studies may examine the assessed risk events in different countries using larger samples
Calibrating CII RT283’s Modularization Critical Success Factor Accomplishments
Get PDFModularization is a well-known construction technique where sections of the job are moved from on-site to a fabrication shop. Previously, the researchers identified the 21 most influential Critical Success Factors (CSFs) for successful modularization and quantified the degree of each CSF’s accomplishment by conducting a survey with 19 subject matter experts, and a case study with three modular projects. Through this methodology, the findings relied on the experience of experts. However, still missing from the understanding of modularization CSFs is a validation of the current degree of each CSF’s accomplishment by examining actual modular projects using a sufficient number of samples. This paper presents a comparison of CSF accomplishment degree between 25 actual sample projects (project based) and the industry experts’ survey results (experience-based estimation). The study results indicate that the industry experts made a good estimation of the current occurrence degree of each CSF. The study did identify, however, three significantly overestimated CSFs and three underestimated CSFs. The three most overestimated CSFs are Owner-Furnished/Long Lead Equipment Specification, Cost Savings Recognition, and O&M Provisions. The three most underestimated CSFs are Contractor Experience, Management of Execution Risks, and Transport Delay Avoidance. This study will help the industry to 1) better understand modularization CSFs and their accomplishment statuses; 2) achieve higher modular project performance by accomplishing the CSF