MSA HEADQUARTERS BUILDING
SLIPFORMED LIFT CORES FOR TOWER BLOCK
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'HE four lift shafts and service core for the 18 storeys of the MSA Building are the first in Singapore to be constructed by the Slipform method.
This method, which allowed the shafts to rise at the rate of a floor per day, was adopted in order that the stabilising lift cores could be erected well ahead of the main build- ing. Lifts may then be installed long before completion of the building and an additional benefit is the present use of a temporary lift car to transport workmen and materials.
For this project the slipformwork consisted of double sided vertical forms, 42 in. high, of 3⁄44 in, thick tongued and grooved boarding. There were 2in. x 8in. walers, 7in. below the top of the form and 12in. above the bottom of the form, with 2in. x 4in. verticals at lifting points
From previous page
ing. In addition, a number of hori- zontal grout pipes were provided in such areas, for grouting up later.
In the sub-basement walls, how- ever, vertical holes in the concrete alongside each sheet pile joint and running the complete height of the wall were formed by steel pipes wrap- ped in polythene, and grouted.
Hydrostatic Test
Provision was made for sand pock- ets at about 30 ft. centres outside the membrane under the floor slabs, to enable the substructure to be hy- drostatically tested.
Cost
The contract rates for the grouting of the floor were M$1.17 and M$1.27 per sq. ft. for horizontal and sloping areas, respectively, and that for the sub-basement walls, M$1.00 per lineal foot.
Far East Architect & Builder July, 1967
and other bracings. Spaced at 5ft. to 6ft. intervals were a total of 28 jacks which climbed on lin. mild steel rod. The jacks acted against steel yokes which in turn supported the forms.
Each jack was connected hydrauli- cally to a central pump which simul- taneously fed all jacks with oil under balanced pressure and caused each jack to climb slowly up its jack rod. The jacks automatically lifted the whole of the assembly deck, form- work, materials. A hanging scaffold provided a platform for the inspection of the concrete emerging below the shuttering level and any necessary surface treatment.
The original structural design of this project did not call for the use of the slipform method of construc- tion. However once adopted by the architects and consultants, the method entailed only one major
General
The architects for the project are Malayan Architects Co-Partnership. The quantity surveyors are Wolferstan, Trower and Partners. Consulting en- gineer was Y. S. Lau.
The substructure and piling con- tractor was Wing Co., and the water- proofing sub-contractor was Treego Trading Ltd., backed technically by American Cyanamid Co., who sup- plied the chemicals, and Power Elem- ent Co. (Nevander Grouting) who supplied the mixing and pumping equipment, for the grout membrane. Concrete additives were manufactured by Sealocrete Ltd. and supplied by Malayan Builders' Merchants.
Tests on samples of grout were carried out by PWD, Kuala Lumpur; Dept. of Physics, University of Ma- Research Unit, EDB, Singapore. laya, Kuala Lumpur; and Industrial
References: Water excluding structures, L. R. Creasy and L. Scott White ICE Proceedings, September, 1959.
Completed core 1966
a view taken in April
design change. All hoop reinforcing was changed either to straight bars or bars with short hoops as it was im- possible to place hoop reinforcing without first cutting and then splicing.
The lift shafts which combined to form the main shear walls to be con- tained within the slim tower block, also support two substantial cantilever beams at each floor. The problem of embedding the heavy projecting splice rods about 6 ft. long for the can- tilever beams was overcome by the use of static panels made to the width of beam connections and the full floor height in length.
The outer form was made with slits just wide enough to clear the static panels which were intially an- chored to the base slab. Special yokes were used to hold the outer form where the slits were formed.
Carried out on a discontinuous pour method and working only dur- ing daylight hours, a floor of 11 ft. 9 in. height was completed on each working day. Rate of climb averaged 13 in. per hour.
Concreting was stopped each day at the under-side of the deepest beam. In the evening the carpenters placed 1 in. x 4 in. key strips to form re- bates for wall to floor connections and block outs for beam and door openings while the steel fixers fixed in
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