In-situ concrete frameworks in multifamily buildings : Modelling and simulation of construction methods and activities
Larsson, Robert LU
(2010)
In TVBK-1038
- Abstract
- In Sweden and elsewhere in the world the construction industry has encountered criticism due to its lower productivity gains in comparison to other industries. This is why continual improvement of processes and forms of cooperation are important, as is utilisation of technologies giving greater efficiencies. The focus in Sweden has mainly been on the construction of multifamily buildings, both because this is an important segment for the country, and because the segment contains, by general consensus, considerable potential for improvement. In Sweden a common method for constructing the framework of a multifamily building is to cast it in-situ using a permanent or traditional formwork system. The method of construction is to a large extent... (More)
- In Sweden and elsewhere in the world the construction industry has encountered criticism due to its lower productivity gains in comparison to other industries. This is why continual improvement of processes and forms of cooperation are important, as is utilisation of technologies giving greater efficiencies. The focus in Sweden has mainly been on the construction of multifamily buildings, both because this is an important segment for the country, and because the segment contains, by general consensus, considerable potential for improvement. In Sweden a common method for constructing the framework of a multifamily building is to cast it in-situ using a permanent or traditional formwork system. The method of construction is to a large extent dependent on the site in question, involving coordination of various work teams so that they can perform their specific jobs. Given that the work is often carried out on sites that do not have the best of conditions for construction operations, unforeseen events commonly occur that influence the progress of the work. This contributes to the fact that productivity on building sites is often low. Another major cause of low productivity in construction projects is a lack of proper planning and control. Implementation of the stages in the work does not just depend on other work associated with or connected to them, but also on the availability of resources, such as formwork, cranes and building materials. Unfortunately, far too little time is devoted to a critical audit of how the work is organised and how the resources are used, and this means that shortcomings are not always noticed until a later stage when it may be difficult to do anything about them.
Discrete event simulation is an established method for studying the interaction of machines, people and materials in various types of process. Today the method has become fully established within the manufacturing sector for analyzing and developing manufacturing processes. In the construction sector, however, the method is still unknown, even though it has been applied in a number of research projects in order to study and develop construction-related processes.
In this research project discrete event simulation is used to study the construction of in-situ concrete frameworks. The project has two aims. The first is to describe the use of techniques and methods in the construction of in-situ concrete frameworks and to study the efficiency of the activities chosen. The second is to develop a simulation model and show how the model can be used to study and evaluate construction methods for in-situ concrete frameworks.
A survey of the use of methods and techniques was undertaken by interviewing site managers in 38 ongoing projects. The projects were selected using a precise selection process to ensure they are representative. Efficiency in a number of activities linked to framework construction operations was studied with the help of activity sampling in two different projects.
The survey showed that the use of techniques for formwork construction, reinforcement and casting was relatively similar across all 38 projects. Of those methods that contribute to increases in productivity, filigran-elements were the most common. The activity sampling measurements uncovered a number of activities having potential for greater efficiency. One such activity was the setting up and dismantling of wall formwork.
The simulation model was developed by studying the work process for framework construction in four projects. First a conceptual model was developed containing a detailed description of the component activities and use of resources. The description from the conceptual model was then implemented in commercial simulation software. The model simulates implementation of various work processes by dynamically allowing for the availability of various types of resources. A simulation result will give the cost, time and use of resources for the framework construction operations.
The model was tested in an actual project to validate its functionality. It proved to be possible to reproduce the times observed on the basis of the actual framework construction operations. However, given that the availability of data from the project was somewhat limited, additional tests on the model are recommended for confirmation of its validity.
The model as constructed is limited to simulating in-situ concrete frameworks and is valid in the first instance for those projects that were studied. To increase its possible applications, generalisation of the model is therefore desirable, and it also needs to be made more user-friendly. Mention is also made of a number of details of the model that might prove worthy of further development.
To demonstrate the potential of the simulation model as developed, a number of different production scenarios were simulated. The first scenario showed how the model can be applied for so-called bottleneck analysis. In another scenario, the model is used to compare two different formwork systems, i.e. precast double walls and a traditional formwork system. It proved possible in theory to reduce the time for the framework construction stage by up to 40% if precast double walls were used instead of a traditional formwork system, but the downside was that the framework did cost more. It ought, however, to be possible to convert this additional cost for the framework into a lower overall cost if the shorter framework time is utilised to shorten the overall construction time. In the final example, the duration of the component activities was simulated based on statistical distribution. This is a very interesting application, as it allows of sensitivity analyses, and it can be used to predict how uncertainties and input data or assumptions will affect the production sequence, which in turn can be used to optimise the production system.
This work has shown that discrete event simulation represents a very interesting tool for studying and improving construction-related processes. The method allows complex relationships to be studied in a manner that is not possible using traditional tools. The method is considered to be of particular interest in the study and development of industrialised construction processes.
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Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/924cf674-06be-444e-bde1-754d0ceed28d
- author
- Larsson, Robert
LU
- supervisor
- organization
- publishing date
- 2010
- type
- Thesis
- publication status
- published
- subject
- in
- TVBK-1038
- issue
- 1038
- pages
- 192 pages
- publisher
- Division of Structural Engineering, Lund University
- ISSN
- 0349-4969
- language
- English
- LU publication?
- yes
- id
- 924cf674-06be-444e-bde1-754d0ceed28d
- date added to LUP
- 2020-09-10 17:46:15
- date last changed
- 2022-02-08 02:35:07
@misc{924cf674-06be-444e-bde1-754d0ceed28d,
abstract = {{In Sweden and elsewhere in the world the construction industry has encountered criticism due to its lower productivity gains in comparison to other industries. This is why continual improvement of processes and forms of cooperation are important, as is utilisation of technologies giving greater efficiencies. The focus in Sweden has mainly been on the construction of multifamily buildings, both because this is an important segment for the country, and because the segment contains, by general consensus, considerable potential for improvement. In Sweden a common method for constructing the framework of a multifamily building is to cast it in-situ using a permanent or traditional formwork system. The method of construction is to a large extent dependent on the site in question, involving coordination of various work teams so that they can perform their specific jobs. Given that the work is often carried out on sites that do not have the best of conditions for construction operations, unforeseen events commonly occur that influence the progress of the work. This contributes to the fact that productivity on building sites is often low. Another major cause of low productivity in construction projects is a lack of proper planning and control. Implementation of the stages in the work does not just depend on other work associated with or connected to them, but also on the availability of resources, such as formwork, cranes and building materials. Unfortunately, far too little time is devoted to a critical audit of how the work is organised and how the resources are used, and this means that shortcomings are not always noticed until a later stage when it may be difficult to do anything about them.<br/>Discrete event simulation is an established method for studying the interaction of machines, people and materials in various types of process. Today the method has become fully established within the manufacturing sector for analyzing and developing manufacturing processes. In the construction sector, however, the method is still unknown, even though it has been applied in a number of research projects in order to study and develop construction-related processes. <br/>In this research project discrete event simulation is used to study the construction of in-situ concrete frameworks. The project has two aims. The first is to describe the use of techniques and methods in the construction of in-situ concrete frameworks and to study the efficiency of the activities chosen. The second is to develop a simulation model and show how the model can be used to study and evaluate construction methods for in-situ concrete frameworks. <br/>A survey of the use of methods and techniques was undertaken by interviewing site managers in 38 ongoing projects. The projects were selected using a precise selection process to ensure they are representative. Efficiency in a number of activities linked to framework construction operations was studied with the help of activity sampling in two different projects. <br/>The survey showed that the use of techniques for formwork construction, reinforcement and casting was relatively similar across all 38 projects. Of those methods that contribute to increases in productivity, filigran-elements were the most common. The activity sampling measurements uncovered a number of activities having potential for greater efficiency. One such activity was the setting up and dismantling of wall formwork. <br/>The simulation model was developed by studying the work process for framework construction in four projects. First a conceptual model was developed containing a detailed description of the component activities and use of resources. The description from the conceptual model was then implemented in commercial simulation software. The model simulates implementation of various work processes by dynamically allowing for the availability of various types of resources. A simulation result will give the cost, time and use of resources for the framework construction operations.<br/>The model was tested in an actual project to validate its functionality. It proved to be possible to reproduce the times observed on the basis of the actual framework construction operations. However, given that the availability of data from the project was somewhat limited, additional tests on the model are recommended for confirmation of its validity. <br/>The model as constructed is limited to simulating in-situ concrete frameworks and is valid in the first instance for those projects that were studied. To increase its possible applications, generalisation of the model is therefore desirable, and it also needs to be made more user-friendly. Mention is also made of a number of details of the model that might prove worthy of further development. <br/>To demonstrate the potential of the simulation model as developed, a number of different production scenarios were simulated. The first scenario showed how the model can be applied for so-called bottleneck analysis. In another scenario, the model is used to compare two different formwork systems, i.e. precast double walls and a traditional formwork system. It proved possible in theory to reduce the time for the framework construction stage by up to 40% if precast double walls were used instead of a traditional formwork system, but the downside was that the framework did cost more. It ought, however, to be possible to convert this additional cost for the framework into a lower overall cost if the shorter framework time is utilised to shorten the overall construction time. In the final example, the duration of the component activities was simulated based on statistical distribution. This is a very interesting application, as it allows of sensitivity analyses, and it can be used to predict how uncertainties and input data or assumptions will affect the production sequence, which in turn can be used to optimise the production system. <br/>This work has shown that discrete event simulation represents a very interesting tool for studying and improving construction-related processes. The method allows complex relationships to be studied in a manner that is not possible using traditional tools. The method is considered to be of particular interest in the study and development of industrialised construction processes.<br/>}},
author = {{Larsson, Robert}},
issn = {{0349-4969}},
language = {{eng}},
note = {{Licentiate Thesis}},
number = {{1038}},
publisher = {{Division of Structural Engineering, Lund University}},
series = {{TVBK-1038}},
title = {{In-situ concrete frameworks in multifamily buildings : Modelling and simulation of construction methods and activities}},
year = {{2010}},
}