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CR Construction Company Limited
CR Construction Company Limited (CRC) commenced work on the iconic new 32-storey commercial office tower for Bonny Ace Limited (Subsidiary of Chinachem Group) in November 2016. Construction of this landmark new Wan Chai development completed in February 2019.
The One Hennessy form is unique. Constructing a single 150-meter high premium Grade A office building with an inverted pyramid structure at its core, the team had to operate in a congested working space with limited site access for five months of temporary works. The space was so limited that even finding room for tool, materials and machinery was logistically challenging. Therefore, CRC’s role in designing and implementing active work schedules, logistic plan and fostering team spirit are the prime contributing factors to the successful delivery of this project.
INVERTED PYRAMID STRUCTURE
The One Hennessy has its unique building structural system. The inverted pyramid structure is located between 7/F and 10/F where 8 nos. of inclined mega-size columns are connected to 7/F central core wall at one end and 10/F 3m deep tension beams at the other. Specially designed timber formwork was used for the construction of transfer structures including the inclined columns, 3m deep tension beams and the belt truss, which is supported by a combination of heavy-duty scaffolding (i.e. Ring-lock) and traditional scaffolding. The falsework was supported by a custom-designed temporary steel deck at level +31.75mPD.
TEMPORARY STEEL PLATFORM
Traditional falsework would occupy all the space from 3/F podium down to basement floor (foundation floor), not only suspending the progress below the transfer structure but also involving a huge amount of falsework material on-site. Therefore, a temporary steel platform was used. The platform consists of main girder (i.e. UB914x305x289 kg/m and UB1016x305x437 kg/m) which is spanning between the concrete grade C60 core wall and steel post (UC356x406x340 kg/m) with moment-resisting connections. The main girder supports the decking (FSP III) to provide a flat surface for the falsework erection.
With the temporary steel platform, the number of scaffolds (3/F to 7/F) was minimized which means the max. height of scaffold is also reduced, from (18.9mPD to 52.9mPD) to (33.125mPD to 52.9mPD). The platforms also created extra space to store machinery, tools and materials. The on-site logistics is smoother and less material was delivered on-site, thus CO2 emission in the logistics process can be reduced as well.
Read more this project in the previous coverage:
GENERAL METHODOLOGY FOR THE CONSTRUCTION TEMPORARY STEEL PLATFORM
The key components of the temporary steel platform consist of:
- Vertical posts;
- Main girders;
- Type 1: Supported by diagonal bracing fixed on core wall
- Type 2: Supported by spanning between core wall and vertical posts
- Secondary beams;
- FSP III sheet piling decking;
- Diagonal bracing between core wall and vertical posts
After installation of vertical posts and its temporary bracing, 8 groups of falsework (Ring-lock system) tower are erected directly below all the main girders to act as temporary support. The main girders are situated by following the final setting out and level. After confirmation of setting out and level for main girders, the end of Type 2 is fixed to vertical posts according to approved drawings. Then the secondary beams are erected spanning between all the vertical posts and main girders following by the installation of sheet piling decking.
In conjunction to the installation work of the secondary beams, the concreting works for the core wall are continued, and cast-in anchor bolt at 5/F, 6/F and 7/F is installed once the core wall reached the relevant floor level. After completion of concreting works, final checking of the setting out for cast-in anchor bolt is performed following by the installation of the baseplate. Upon the completion of concreting works at 7/F, main girders are connected to the core wall through the designed baseplate. Lastly, all the diagonal bracing is installed correspondingly.
The temporary falsework and the temporary bracing for vertical posts are not removed until all the steel members have been fully installed, and the relevant core wall has obtained its design strength (C60).
BUILDING INFORMATION MODELLING
Spanning between core wall and vertical posts, the main girders would inevitably penetrate some of the RC structure outside core wall, which makes the temporary steel platform design works complicated in order to avoid damaging structural bearing elements. For a better understanding of the structure conditions outside core wall, Building Information Modelling (BIM) was fully utilized to demonstrate the spatial relationship between members of the temporary steel platform and parent RC structure for a more accurate and feasible design. BIM also visualised construction method of the whole inclined structure construction process, which helps improve project planning as well.
Mr. GUAN Manyu
Chairman of CR Construction Company Limited
Mr. Guan has approximately 20 years of experience in the construction industry. He was admitted as a 1st class registered constructor in specialty of construction engineering in Ministry of Housing and Urban-Rural Development of the People’s Republic of China in November 2007 and a senior engineer in specialty of construction engineering in Zhejiang Province Human Resources and Social Security Department in December 2009. He is responsible for overall business development as well as financial and strategic planning of the company.
Mr. SHEN Kai
Business Development Department Manager of CR Construction Company Limited
Mr. Shen has approximately 8 years of experience in the construction industry. He was admitted as a 1st class registered constructor in specialty of construction engineering in Ministry of Housing and Urban-Rural Development of the People’s Republic of China in April 2015 and an engineer in specialty of construction engineering in Zhejiang Province Human Resources and Social Security Department in September 2015. He is responsible for the project cost management of the project.