History St. Helen's (skyscraper)

1 history

1.1 design , development
1.2 construction
1.3 awards

history
design , development

in 1961, commercial union assurance company had acquired site in st mary axe, in city of london, desired develop new headquarters. site comprised adjacent properties in st mary axe , former shell building in great st helens. @ same time peninsular , oriental steam navigation company planning redevelop city offices in leadenhall street.

due number of issues affecting both sites, notably poor access commercial union site , restricted width of peninsular , oriental site, not possible obtain planning consents optimise amount of floor space desired either company. result, 2 companies decided participate in joint development involve reallocation of site boundaries , creation of open concourse area @ junction of leadenhall street , st mary axe. both companies have frontages on new concourse , retain site areas equivalent enclosed original boundaries.

the architect project gollins melvin ward partnership, acknowledged influence of mies van der rohe. design elongated cube in modernist international style. original cladding (apart windows) anodidized aluminium, colour changed in varying lighting conditions dark grey dark bronze.

the tower has 24 usable office floors. in addition there 2 double-height plant floors; boiler rooms on 1 of plant floors serviced neighbouring peninsular , oriental building. floor-to-site-area ratio 5.5:1. there 5 underground levels, providing staff restaurant, garage , 3 levels of storerooms , strongrooms.

below lowest office floor, design broken open podium designed provide elevated pedestrian access via city of london pedway scheme. pedway ambitious unfulfilled scheme improve traffic flow in city of london means of construction of network of elevated pedestrian walkways. mid-1960s 1980s, developers of major sites required provide access pedway network condition of obtaining planning consent. requirement unpopular designers, regarded results visually unappealing unused space provided pedestrians dead ends. in case of development, podium-level walkway constructed linked commercial union building neighbour, peninsular , oriental building.

construction

the commercial union building under construction in 1968. office floors suspended steel trusses cantilevered mid- , roof-level plant floors

the construction of commercial union building undertaken taylor woodrow construction.

the structure comprises central concrete service core, surrounded steel framework suspended projecting steel truss sections @ mid- , roof-level plant floors. office floors suspended these steel frameworks; roof section supports twelve floors while midsection supports thirteen floors. steel hangers installed in alternate window mullions , vary in size: 0.23 m × 0.05–0.23 m. suspended construction design aimed @ maximising floor space largely eliminating need support columns.

the new piazza in front of 2 new buildings below street level, , steps constructed on 2 sides. air intake louvres ventilating building s 5 sub-surface levels built treads of steps. piazza planted semi-mature lime trees.

awards

in 1970, commercial union , peninsular & oriental buildings won civic trust award townscape , design co-ordination. in same year commercial union building awarded structural steel design special award, sponsored british steel corporation , british constructional steelwork association.