The construction of a new Biological Life Science Centre at the University of Bristol has had to cater for a steeply sloping site with difficult access issues and particularly vibration-sensitive neighbours.
Project: University of Bristol Life Sciences Building
Client:: University of Bristol
Contract value: £34m
Contract type: NEC Option A – Design and build
Main contractor: Vinci
Concrete frame subcontractor: Midwest Formwork
Architect: Sheppard Robson
Engineer: Capita Symonds
Quantity surveyor: Davies Langdon
Start date: March 2012
Completion date: November 2013
If a university or college is to keep its place at the top table of research funding, it needs to be able to attract the top undergraduates and academics by offering them the best facilities in which to carry out their studies.
This is exactly why the University of Bristol is spending more than £50m on the development of its new centre of excellence for biology research and teaching, the Life Sciences building.
Perched on the edge of a hard sandstone knoll that dominates the city centre, the university can scarcely have chosen a more challenging site for the scheme, which is being carried out under a £34m deal with main contractor Vinci Construction.
Building next to an ultra-sensitive site
Not only is it sitting on top of the sandstone occlusion but it is also being built directly adjacent to one of the UK’s most sensitive buildings – the university’s Centre for Nanoscience and Quantum Information – while its School of Physics is another close neighbour.
It also happens to be on the site of the Royal Fort, the city of Bristol’s former Royalist Citadel during the English Civil War, as well as being in close proximity to hospital buildings.
Those sensitive experiments under way at the NSQI have been moved to the university’s veterinary centre at Langford out in the Somerset countryside, but the rest of the site neighbours have had to be kept well informed of the day-to-day progress.
Getting on with the neighbours
Fortunately for Vinci Construction senior project manager Kieran Mulrooney and University of Bristol director of capital projects Karsan Vaghani, they have an advantage in that most of those directly affected by the work are representatives of the client who understand the importance of what is going on and how it will benefit the university.
“Part of the enabling works package the site has been dug out to around 9 m below the ground floor of the NSQI at its deepest”
Kieran Mulrooney, Vinci Construction
Having taken over the site – after demolition and preparation work including soil nailing and installing rock anchors had been carried out – the Vinci team started work on the scheme in May 2012.
“As part of the enabling works package, the site has been dug out to around 9 m below the ground floor of the NSQI at its deepest,” says Mr Mulrooney. “The site falls away quite quickly from west to east, which affects the design and layout of the building.”
A mixture of concrete and steel frames
In the main, the frame of the structure is built using cast in-situ reinforced concrete with a double level basement at the deepest side adjacent to the NSQI building, which peters out to grade at the far south-east of the site alongside St Michaels Hill.
Levels are defined by the ground floor entrance to the building on Tyndall Park Road, with the lower ground floor and ground floor levels featuring a common structure before the building splits into two separate wings connected by a steel-framed atrium.
The lower ground floor features library space, study areas, controlled environment rooms and an entrance and goods yard at the rear to service the building with the ground floor featuring teaching space, administration areas and seminar rooms.
Where the structure splits, the wing alongside the NSQI building features specialist laboratory space, with the eastern wing devoted to office space.
Throughout the building slabs are of flat reinforced concrete construction at 375 mm thick with perimeter walls at 400 mm thickness.
Waterproof concrete leakage protection
Specialist contractor Midwest Formwork is carrying out all the concrete frame work and has used a three-floor jump form to cast the cores and table formwork from supplier Doka for the flat slab.
It is using waterproof concrete all the way through those underground levels with high strength mixes in the basement and slabs. The waterproof concrete is being used to cut out the risk of water leakage that a tanking system may bring.
“It is almost a design from inside-out”
Karsan Vaghani, University of Bristol
There are no piles, with foundations for the building springing directly from the level of excavated sandstone rock beneath the site.
“Essentially they are pad thickenings,” says Mr Mulrooney. “Typically they are around 2 m thick at the cores and around 1 m thick at the columns and walls.”
Those columns and shear walls across the building have been designed around the anticipated final use with the 9 m column grid in the laboratory space fitting exactly the bench space requirements for the final layout.
The new building is separated from the sensitive NSQI building by a 1.5 m air gap at lower ground and ground floor levels – effectively a huge cavity wall. This gap between the buildings springs out to 4 m or so above ground level to provide isolation to its next-door neighbour.
“It is almost a design from inside-out,” explains Mr Vaghani. “On university capital projects we typically have a lead academic who sits on the project board. It’s a way of making sure the end-user is fully represented.”
That representation leaves the laboratory and research space focused on the work the academics will do within the building, even down to the window spacing on that elevation shared with the NSQI.
Here the elevation is slightly curved and those sections between the windows have helped the designers provide indentations where sophisticated air-handling units, vital for providing climatic control to the experiments, are to be installed.
Variable ceiling heights
Floor to ceiling heights vary between that of 3 m in the office wing and the 4.5 m of the research wing. That difference in height means the office side has an extra floor between the first and third floors to compensate.
A steel-framed café, breakout area and terrace for staff tops the concrete frame, with large plant rooms above the laboratory wing and a state-of-the-art greenhouse that will allow research teams to grow all sorts of tropical fancies beneath the Bristol sun.
Vinci Construction is set to hand the project over in November 2013, with intended occupation after the Christmas break in January 2014.
By this time the promise of new world-class research facilities should be attracting more students to the renowned university.
Site access and surroundings pose challenges
With the sharply dipping site for the university’s latest addition to its building stock being located on the edge of a hill, as well as being bounded by two busy roads and a host of sensitive buildings, it is unsurprising that getting construction deliveries onto site has proven challenging.
“We can take deliveries throughout the day, but the streets can get very busy around here at times and not necessarily just with vehicles,” says Mr Mulrooney.
“Every hour we have thousands of students walking around as they finish lectures and they can be difficult to manage, too.”
Two tower cranes service the site with a small lay-down delivery area taking over part of the main highway St Michael’s Hill alongside the eastern side of the site.
Concrete from Tarmac’s nearby St Phillips batching plant is delivered to the site and placed using two concrete pumps, the location of which had to be carefully plotted thanks to locations of the two tower cranes, which measure 50 m in radius and 55 m high and 40 m radius and 45 m high respectively.
“We tend to work on the volume of concrete we can bring onto the site without causing any traffic issues,” says Mr Mulrooney. “We try not to have much more than four wagons delivering each hour because it is logistically difficult.
“The concrete pumps could easily handle more but we don’t want wagons stacking up around the streets of Bristol.”
Although the recent stormy weather has meant the team has been unable to use the two cranes, the team has been able to continue concreting thanks to the pumps that are able to reach all the vertical members. It means that the team is on track to complete the frame in time for the Christmas break.