Beaulieu 25 is a typical TCA style development of three linked eightstorey blocks on the south eastern edge of the city centre. The site is somewhat less challenging than the Lex 2000 project (see p19), which means a much purer precast concrete solution is possible.
'Almost every concrete element except the foundations, the diaphragm walls around the basement and the 50mm structural topping on the floors, is precast, ' explains Waterman TCA project engineer Sandrine Leroy.
'This includes the cores, which are made up from 50mm thick precast permanent formwork filled with 100mm of insitu. Corbels on the precast pick up the precast landings.'
Concrete of grade C50/60 is the standard mix for the precast elements. In the three basement car park levels, two hours' fire resistance is specified. Here the internal columns are cast three storeys high, with slim corbels to pick up the floor beams. These are the classic pretensioned prestressed units with fairly straightforward joints and connections. Flooring is the generic pretensioned, prestressed hollow-core units 200mm thick, topped eventually by 50mm of reinforced structural topping.
Above the ground floor one hour fire resistance is the norm and a simpler but more elegant structural form is adopted. Fair faced circular columns are single storey, each with four bars in 'diamond' formation projecting from their heads. Single span beams sit on the column heads, with two of the bars passing between their ends and each of the other two passing through holes in the beam ends. Ducts cast into the feet of the next storey columns pick up the four bars as the columns are lowered onto the beams below, a nonshrink grout seals the bars into the ducts.
Structural erection began in late February year after the completion of the diaphragm wall. The frame is due to be finished in October.