Construction World December 2021

SPECIALIST CONTRACTORS OR SUPPLIERS

achieved wi thin al lowable tolerances . Temporary works, post-tensioning, and anchor plates The temporar y sacri ficial concrete support columns to the deck formwork system requi red addi t ional structural strengthening to ensure compat ibi l i ty wi th the temporar y force di stribut ion during al l construct ion stages . For thi s SikaWrap®-300 C, a high-qual i ty unidi rect ional woven carbon fibre wrapping system was speci fied. The SikaWrap®-300 C confined the head of the temporar y concrete support columns , in combinat ion wi th Sikadur ®-330, a structural impregnat ing epoxy res in adhes ive. SikaWrap®-300 was chosen for i ts high load capaci ty, easy appl icat ion and quick instal lat ion, saving t ime and money on the project . The Sika® CarboDur ® FRP Des ign sof tware, a state-of-the-art external structural strengthening des ign program was an added benefi t , making the des igning process feas ible. The instal lat ion of tendons and stay cable tens ioning was a technical ly complex operat ion successful ly per formed by Amsteel during various stages of construct ion. Al l -Weld Marine & Industrial , who successful ly manufactured the compound steel anchor plates in a record t ime. Founding level variations of the west abutment During the excavat ion operat ions for the western abutment foundat ion, af ter instal lat ion of the lateral support i t was found that the founding material dipped away sharply towards the rear of the abutment , especial ly on the s ide of the bridge in i ts temporar y pos i t ion. The founding material strength was cons iderably lower than the strength at the temporar y abutment pos i t ion. Thi s founding material strength variabi l i ty impl ied certain sett lement impl icat ion in terms of the des ign bearing pressure. A comprehens ive

the des ign, construct ion stage and in-ser vice analys i s . Thi s al lowed an accurate s imulat ion of the t ime- dependent material behavior wi th the poss ibi l i ty of force adjustments during construct ion. The updated models were cal ibrated for determinat ion of the fol lowing: • Stay cable length determinat ion, which requi re long procurement lead t imes appl icable to internat ional suppl iers . • Hanger force di stribut ion opt imi sat ion. • Pre-camber requi rements and influence of temporar y works di splacements . • Movement capaci t ies of temporar y, permanent bearings and expans ion joints . • Geometr y control by structural deformat ion val idat ion. Through a speci fied laborator y test ing programme, the des i rable concrete mix propert ies were selected; parameters whi le also providing technical inputs to a construct ion stage fini te element model . Construct ion methodology of large volume concrete elements was planned wi th due care and management of thermal per formance aspects . Structural behaviour monitoring, assessment and verification An extens ive moni toring plan was prepared for construct ion and included system ident i ficat ion by ful l - scale dynamic test ing as wel l as structural behaviour veri ficat ion by deformat ion measurements , requi ring cont inuous model l ing and moni toring during al l construct ion stages . Deformat ion measurement was part icularly cri t ical during the hanger tens ioning phase, where the deformat ion of the arch ribs was measured and compared to theoret ical deformat ion predicted by the cal ibrated FEM models . Load cel l , extens ion and vibrat ion readings were correlated to ensure that the intended cable force values were favouring structural and thermal per formance propert ies , as wel l durable and sustainabi l i ty

42 20 th Best Project Awards 2021