Modular and Offsite Construction (MOC) Summit Proceedings
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Testing and numerical analysis on cold-formed steel shear walls using corrugated steel sheathing
Get PDFCold-formed steel framed shear wall sheathed with corrugated steel sheets is a promising shear wall system for low- and mid-rise constructions at high wind and seismic zones due to its advantages of non-combustibility, high shear strength, and high shear stiffness. Monotonic and cyclic tests on full-scale wall assemblies using corrugated steel sheathing was conducted. To investigate the effect of vertical/gravity loading, shear wall specimens were tested under two different loading conditions: lateral loading, and a combined lateral and vertical/gravity loading. The test results are presented and discussed in this paper. Besides, finite element model of the proposed shear wall was created in Abaqus software. The validity of the numerical model was verified based on the test results. A series of parametric analysis were conducted, including the thickness of framing members, the cross section of stud members, yield strength of the frame members, stud spacing, and the influence of gravity loads. The detailed modeling information, relevant parametric analysis and recommendations for practical application of this type of shear resisting system are also presented
Experimental investigation on torsional behavior of composite beams reinforced with two-piece enclosed stirrups
Get PDFThis paper presents an investigation of the torsional behavior of reinforced concrete (RC) beams which were cast twice and reinforced with two-piece enclosed stirrups. Their torsional behavior was compared with those of monolithically cast RC beams with conventional stirrups using a customized test setup. The test program was divided into two groups to distinguish different influencing factors. Results from the first test group indicated that the maximum torques of monolithically cast beams reinforced with two-piece enclosed stirrups decreased by an average of 3.7% compared to those reinforced with conventional stirrups. The second test group revealed that the maximum torques of composite beams increased by 6.7% compared to those of monolithically cast beams. As a whole, minor differences in the maximum torques and deformation capacities were found between composite beams reinforced with two-piece enclosed stirrups and monolithically cast beams reinforced with conventional stirrups
Application of machine learning approach for logistics cost estimation in panelized construction
Get PDFLogistics operations in panelized construction are vital daily tasks that connect the panel manufacturing facility to the job site. Although logistics operations are both important and prevalent in panelized construction, the cost of logistics has yet to be fully understood by either industry or academia due to the complicated relationship between multiple factors in logistics demands and operations. In practice, logistics is considered as an overhead cost that consists of various indirect or fixed costs in the panelized construction operation. As a result, logistics cost estimates are rendered inaccurate when subjected to project changes. Considering the number of construction projects over the course of a year, inaccurate logistics cost estimates are significant. Previous studies have shown that a machine learning approach could be used to predict costs that are influenced by multiple factors. To fill knowledge gaps in both research and practice, in this study machine learning based on historical logistics data is used to accurately predict logistics costs for a given project. The results from this study indicate that machine learning can be a reliable tool to predict logistics costs
Assessment on the carbon efficiency in the construction stage: A comparative study between prefabricated and conventional construction
Get PDFConstruction industry is the consuming large amounts of natural resources and at the expense of a heavy environmental burden. Therefore, we need to keep a balance between creating economic benefit through construction and focusing on the influence to the environment with the aim of the value of carbon emissions maximize. The paper puts forward carbon efficiency which provides a linkage between carbon reduction and value creation of construction effectively can reflect construction efficiency. The essence of carbon efficiency is using the lowest environment output to build a construction. Through analysing two cases, result shows that carbon efficiency of prefabricated construction is higher than the conventional construction’s, which improves 25%. Besides, the measures are provided to improve the carbon efficiency of constructing. Enhancing the precast level, implementing prefabricated components standardized, optimizing site management is the main key to realize the low carbon construction
Pull-out tests of a new hooked steel-GFRP composite connector in precast concrete sandwich panels
Get PDFA new hooked steel-GFRP composite connector was proposed for precast concrete sandwich panels. The new connector consisted of a steel core and glass fiber-reinforced polymer (GFRP) as outer covering layers processed by injection molding machines. It was intended to connect the inner and outside layers of precast concrete sandwich panels with high structural performance, low thermal conductivity and ease of installation. To investigate the anchoring capacity of the new connector in concrete, pull-out tests were carried out on total 9 test specimens. Experimental results were analysed including pull-out strength, failure pattern, load-slip curve and load-strain curve etc. Results show that all the test specimens fail with the pattern of pulling out of concrete cone. Slippages between the connectors and concrete remain negative when the specimens were damaged. Hook of the connector linking the intersection of reinforcing bars improve the pull-out capacity significantly. The pulling-out capacity of the new connectors increase with the increment of concrete strength grade; and the average pulling-out capacity of the connectors become more than 5 times pulling-out load required by the Chinese code
Manufacturing of modular buildings: A literature review
Get PDFThe recent decade has seen a growing interest in applying modular construction in high-rise buildings. However, the manufacturing of modular buildings remains slow in making technical progress and the productivity in the factory is low. The production of modules is unique and complicated as it incorporates both manufacturing features and construction trades. Whereas previous studies have proposed technologies and tools associated with design, operation and optimisation of module manufacturing systems, this field of research is currently fragmented. This paper aims to provide a systematic review of existing academic perspectives and suggest future research directions to improve module manufacturing systems. The review explores critical research issues from five aspects: process and activities, organisation and people, factory configuration, technology, and information and control system. Outlined suggestions for research opportunities include (1) increased utilisation of digital manufacturing, (2) more exploration of strategies for the adoption of automated technologies, (3) development of holistic and practical approaches to supporting DfMA methodology, (4) well-defined information management systems through BIM. The findings should contribute to a more comprehensive understanding of the practices, challenges and the state-of-the-art research in the manufacturing of modular buildings
Damage assessment of semi-precast slabs using impact-echo method
Get PDFSemi-precast slabs are widely used in precast concrete constructions in China nowadays.However the construction quality of them are often hard to control, and the constructoion quality of the upper in-situ concrete of them is difficult to be guaranteed, as a result, how to detect the construction defects correctly and timely become more and more important. In this paper a traditional method Impact-Echo (IE) method is used to detect the flaws between the precast concrete and the upper in-situ concrete of the semi-precast slabs. Firstly one experimental slabs with many designed flaws was constructed, and than IE method was used to detect these flaws, fially the detected results were analysed to evaluate the proposed method. The results were processed using a mapping strategy, which indicated suspicious points where core extraction was undertaken. All cores taken from points derived from IE method results were found to have flaws providing evidence. The experimental results show that IE method may be a suitable tool to assess the construction quality of Semi-precast slab
Front matter, 2017 MOC Summit proceedings
No full textProceedings of the 2017 Modular and Offsite Construction (MOC) Summit held in Shanghai, China, November 10 - 12, 2017
Research and discussion over seismic performance of modular structure
Get PDFModular structure is a new type of steel building with special construction to shorten the construction period and bring other benefits. Some studies on seismic performance of modular structures were introduced. In order to meet much higher seismic requirements with less steel usage, a new type of pretensioned modular frame was proposed, which can develop a more rigid connection between modules. A quasi-static loading test was performed on a full-scale pretension assembled framed modular system, which demonstrated seismic performance of modular connection can be improved through an effective connection. Finally, some technical proposals have been discussed in structural arrangement, calculation method as well as lateral resistant system
Planning of modular construction manufacturing plant layouts using non-linear optimization
Get PDFThe layout of a manufacturing facility has a significant impact on its productivity and effectiveness, as evidenced by the large amount of research surrounding the facility layout problem and optimization of the solution. In the continually evolving modular construction industry, the solution to this problem will change as often as any smaller adjustment is made to the production line. Because of this continual evolution, it is not possible to continuously change the layout, as this would quickly become prohibitive because of the cost and the need to stop production. This paper presents an optimization of the number of stations per department using the generalized reduced gradient (GRG) optimization algorithm to balance the production line. The benefit of using this algorithm is that it presents the near optimal number of stations in each department and allows for quick modifications to achieve the feasible number of stations in the ever-changing environment