I will always try to find real applications for what we design and build.
You have been with Samsung for some time now. What has your journey been like?
Since joining Samsung in 2004, I have overseen the division transition from a traditional construction-only provider into the successful design-build, pre-construction, value engineering, and fast track design/construction for high-rise and complex buildings. I have been involved with many projects at Samsung, most notably in all aspects of construction planning, pre-construction services, and structural design of the Burj Khalifa, the Jumeirah Gardens in Dubai, Samsung HQ, Seoul, the 151-story Inchon Tower, and the Yongsan Landmark Tower (a 620m- tall , 111-storey tower) in Seoul.
You possess a wealth of knowledge and experience. How do you share it with the industry?
In addition to presenting at several international professional conferences and workshops, I also serve as a lecturer at Seoul National University where I teach graduate classes the structural design of high-rise buildings and spatial structures. I have also served as an adjunct professor at the Illinois Institute of Technology´s School of Architecture, where my research interest included the development of innovative structural systems in concrete/steel/composite structures, and in aerodynamic shaping of super tall buildings to mitigate wind effects, to reduce the dynamic wind forces and resonant vibration. It is important to note that these mitigation measures were later incorporated in real projects including the Tower Palace III, the Burj Khalifa, and the Twisted Towers.
YWhy are you participating in this conference?
This conference is a celebration of the accomplishment of giants in the concrete industry; those who have contributed significantly to where we are today. The calibre of the people attending the conference will no doubt allow me to exchange significant information that is critical to what we do today and to what the future may hold. I had the opportunity to work with some of these giants and this conference will allow me to meet them again under a single roof.
YWhy have you chosen the topic you are speaking on?
I have chosen two topics to speak about at the conference which I believe are dear to every engineer, in terms of getting feedback on the work we do. Engineers design many buildings through their professional careers but most are not / never able to correlate their design to the actual response and behaviour of the building to forces imposed on them during their life, including but not limited to gravity and lateral loads.
This paper takes the reader into a journey of my involvement as the senior structural engineer of the project responsible for developing the structural and foundation design of the Burj Khalifa tower, to being involved in the construction as the chief technical director of the project and in developing the construction planning, logistics, execution strategy, evaluation of the building structure as we build for the entire project, ensuring that the project is delivered to the highest quality and standards, and being able to conceptualise and execute one of the most comprehensive real- time structural health monitoring programmes of its kind. All that gave me a complete feedback on the structural behaviour of the building in all aspects, starting from the foundation to the tip of the pinnacle at 828m above the ground. Therefore, I had the luxury to design, build, and still continuously test the tallest man- made structure in the world.
I hope that sharing my Burj Khalifa experience with engineers/building authorities/ owners/ developers. may give them the opportunity to set up such programmes for all essential and important facilities. This will give us feedback on the buildings we design and aid us in improving on them in the future. I am now testing the building in full scale and there is no better way to do it.
What are your expectations from this conference?
This conference will allow me to share knowledge, information, and to have a better understating of the future direction of the concrete industry and best practices from the giants in our industry. I will always try to find real applications for what we design and build.
Tell us a bit more about the content you will be sharing through your paper?
My paper is titled `Validating the Structural Behaviour and Response of Burj Khalifa: Full Scale Structural Health Monitoring Programmes.` A new generation of tall and complex buildings reflects the latest developments in materials, design, sustainability, construction, and IT technologies. While design complexity can be managed through advances in structural analysis tools and software, ultimately the design of these buildings still relies on minimum code requirements that are yet to be validated in full scale.
My involvement in the design and construction of the Burj Khalifa from inception until completion prompted me to develop an extensive survey and real-time structural health monitoring programme to validate the assumptions made during the development of the design and construction planning of the tower.
At 828m, Burj Khalifa is the world´s tallest man-made structure, composed of 162 floors above grade and three basement levels. The focus of my paper is to provide a brief description of the structural and foundation system of the tower and to discuss the development of the survey and real-time Structural Health Monitoring Programmes (SHMP). Correlation between the predicted and actual measured structural behaviour will also be discussed; however, because of confidentiality clauses, the actual measured data cannot be disclosed at this time.
The SHMP included:
- Monitoring the tower´s foundation system.
- Monitoring the foundation settlement.
- Measuring the column/wall strains and shortening during and after construction.
- Real-time measuring of the tower lateral displacement and dynamic characteristics during construction.
- Measuring the building lateral movement under lateral loads (wind, seismic) during construction.
- Measuring the building displacements, accelerations, dynamic characteristics, and structural behaviour during service life.
- Monitoring the pinnacle dynamic behaviour and fatigue characteristics.
- While the SHMP developed for the Burj Khalifa was a futuristic model at the time, this field is constantly evolving and a new generation of SHM systems will emerge that uses the latest technological advances in devices and IT technologies.
Can you share some industry developments related to the subject you intend to present?
Presently, in China, there are similar programmes being executed and that may follow the same programme presented in this paper. There are only a few buildings in the world that have been designed, constructed, and monitored by the same engineer. This provided a complete and rare loop of linking the design to the final behaviour from the point of view of the original designer´s perspective. The idea is to validate all the assumptions made in the design and to give assurances how to build better and push the limits to the next level while developing the next generation of tall building systems.
Do you have a message for ICR readers?
Traditionally, the design and construction of tall buildings relied solely on minimum building code requirements, fundamental mechanics, scaled models, research, and experience. While many research and monitoring programmes have been done on tall buildings, these programmes had a very limited research and scope and were yet to be systematically validated or holistically integrated. The development of the comprehensive SHM programmes at the Burj Khalifa provided immediate and direct feedback on the actual structural performance of the tower, from the beginning of construction and throughout its lifetime, and includes the following:
- Testing all concrete grades to confirm the concrete mechanical properties and characteristic (strength, modulus of elasticity, shrinkage and creep characteristics, split cylinder, durability, heat of hydration, etc).
- Survey monitoring programme s to measure the foundation settlement, column shortening, and tower lateral movement from the early construction stage until the completion of the structure.
- Strain monitoring programme to measure the actual strains in the columns, walls, and near the outrigger levels to confirm the load transfer into the exterior mega columns.
- Survey programme to measure the building tilt in real time, and the utilisation of GPS technology in the survey procedure.
- Temporary real- time SHM programme to measure the building acceleration, displacement, and to provide real-time feedback on the tower dynamic characteristics and behaviour during construction.
- Permanent real-time SHM programme to measure the building acceleration, movement, dynamic characteristics (frequencies, mode shapes), acceleration time history records, wind velocity and direction along the entire height, and fatigue behaviour of the spire/pinnacle.
- The data collected from the above survey and SHM programmes were found to be well in agreement with Samsung- predicted structural behaviour.
- The survey and SHM programmes developed for the Burj Khalifa have:
- Validated the design assumptions and parameters used in the design, analysis, and construction techniques;
- Provided real-time information on the structural system response and allowed for potential modification to the construction techniques, to ensure the expected performance during construction and through its lifetime;
- Identified anomalies at early stages and allowed for means to address them; generated very large in-situ data for all concrete materials used for the tower.
- Provided full feedback on the foundation and structural system behavior and characteristics since the start of construction.
The survey and SHM programmes developed for the Burj Khalifa will no doubt be pioneers in the use of survey and SHM programme concepts as part of the fundamental design concept of building structures and will be benchmarked as the model for future monitoring programmes for all critical and essential facilities.
Alongside this, advancements in computer and IT technologies, innovative advancement in fiber optic sensors, nanotechnologies, dynamic monitoring devices, new GPS system technologies, and wireless monitoring techniques will be used as a base for future survey and SHM programmes and it will become an integral part of the building design and Intelligent Building Management System.
Learning from the Expert
A galaxy of global experts will soon descend in Mumbai to promote cost-effective and green concrete technologies at the inaugural R. N. Raikar Memorial International Conference. To be held on 20 and 21 December 2013, the event will feature over 88 renowned international experts from the world of concrete.
One such stalwart is Dr. Ahmad Abdelrazaq, Senior Executive Vice President and the Head of the Highrise and Complex Building Division at Samsung C & T Corporation, Seoul, Korea. His paper, `Validating the Structural Behaviour and Response of Burj Khalifa: Full Scale Structural Health Monitoring Programmes` is already generating a lot of buzz within the engineering community and is tipped to be one of the star presentations at the event. Presently, Dr. Ahmad is directly involved in the design and construction of several mixed-use, high-rise and complex building projects in Asia and the Middle East, including the Worli development project, Mumbai.