Client: Hines
DBFL’s engineering team was engaged by Hines to successfully deliver the structural, civil and transportation designs for this complex and challenging major refurbishment and extension project. The commission ran from initial pre-purchase due diligence of the campus through masterplan, scheme design, planning application, detailed design, tender, construction and handover. DBFL’s role involved working and coordinating with the core team and specialist designers & suppliers, specialist subcontractors and temporary works designers and contractors.
DBFL safely and economically delivered the engineering design for Henry J Lyons architect’s vision for the redevelopment of the full campus. This vision included a complete alteration of how the main tower building at One Central Plaza had originally been designed to function.
The project represents one of the most complex re-developments in Dublin city centre in recent times on what has always been a unique landmark structure within the city. The architect’s grand vision involved bringing a previously publicly inaccessible yet imposing building into use as a vibrant centre destination for everyday commercial activity in the beating heart of Dublin city centre. Previously enclosed areas of the plaza and the rooftop are now available for public use and the mix of high-quality office, retail and hospitality space will ensure the Dame Street and Temple Bar areas remain as key economic and social centres in the fabric of Dublin.
Plant risers, lift shafts, stairs and staff facilities housed within the cores were completely modified or reconstructed to deliver the needs of the modern office. To preserve the character of the building and to maintain office floor space from levels 2 to 8 all the above were required to be retained within the confines of two existing cores which remained fully loaded by the hanging structure throughout the construction works. Additional lifts to the office floors and the rooftop hospitality spaces have been accommodated. The repurposing of the roof area, which previously housed plant, to deliver a glass-topped hospitality space affording panoramic views over the city not only necessitated the addition of mezzanine floors, deep trusses and walkways but re-engineering of the entire servicing strategy. A full assessment and refurbishment of the building hanging truss and bars system was required. The two-storey basement car park was partly repurposed to house building plant previously located in the roof space, with the remainder concealed in strategic locations at high level. Some car parking now accessed by carlift was redesigned at the lower basement.
The procedure for all structural work involved the examination of historical information, analysis of the existing and proposed conditions and investigative opening up to inspect and test existing materials against the design criteria. Once complete, we were then able to verify the existing condition or update designs to reflect remedial works required.
As strip out and investigation immediately preceded construction work, DBFL were required to work closely with the design and site teams to develop solutions.
The design had to allow for a viable construction methodology (top down) while maintaining structural integrity in the temporary and permanent states.
Where reconfigured walls were overstressed, load controlled hydraulic flat jacking and screw jacking was used transfer load into new structural concrete/steels.
DBFL had to ensure that the supporting umbrella truss and hanging bars remained within safe carrying capacity and that the various elements of the entire hanging system were in a serviceable condition through extensive surveying work.
Significant intervention and strengthening work was undertaken to ensure the hospitality space at level 9, new mezzanine at level 10, glass roof & new elevated plant space within same could be constructed in lieu of the previously existing roof.
A bespoke hipped glazed roof was designed by Dutch Steel and Glass specialist Octatube with DBFL’s coordinated design providing support at all main frame vertical and horizontal tie in points.
Grand visions are not delivered without hard work, innovative thinking and detailed understanding of the challenges and complexities of the project. The engineering challenges faced were indeed unique due to the ‘hanging’ nature of the original structural design.
The design and construction interventions were at all times required to respect the unique top loaded nature of the building where traditional temporary works propping was not feasible. Undertaking structural interventions on core walls required that the remaining fabric could at all times continue to support the point loads ( upt to 160 Tonnes) from the massive umbrella truss at the top of the building. DBFL ensured effective support was maintained through constant modelling of the cores’ load paths, the definition of works sequences / phases, the redistribution of loading through strategic jacking and the embedment of new structural steelwork within the cores. All the while works were carried out in a busy city centre with associated issues
While not a protected building at the time of site purchase, our client’s intention from a sustainability and heritage point of view was to preserve the existing innovative structure wherever possible.
The deep structural refurbishment of the building frame shows engineering commitment to the preservation of a cornerstone of Dublin’s architectural history. As part of the collaborative design and construction works DBFL have breathed a new extended life by reinstatement of key building elements and the protection of same with modern materials and procedures.
Project Director
