Environmental Impacts of Multi-Storey Buildings Using Different ...

- 91 -buildings has been analysed and compared. Arrow International Ltd., Project ManagementConsultants, was consulted to ensure the construction scheduling for both case studies areestimated with reasonable accuracy.Some assumptions had to be made in order to predict the necessary time needed. Theseassumptions are listed below:• Column and wall members will take one hour to erect after arrival onsite.• Beam members will take half an hour to place after arrival onsite.• Flooring units will take twenty minutes to place after arrival onsite.• The floor topping will be undertaken in two pours, each taking one day.• Architectural fit-out will not be considered for either building.• Available personal onsite will not limit construction time.The buildings are divided into sections in order to increase rapidity of construction. Using thisinformation Gantt charts of the proposed construction sequence were developed for both theConcrete (Figure 7.4Figure 7.4Figure 7.4) and Timber buildings (Figure 7.5).From Figure 7.4Figure 7.4Figure 7.4 and Figure 7.5 above it can be seen that the overallconstruction time for the Concrete building is 67 days and 69 days for the Timber building.The first floor of each structure take the longest time as the foundations must cure adequately.It can be seen that the sub-structure work takes almost one third of the time of construction ineach building. On completion of the first level, the rapidity of pre-fabricated construction isevident. Each level of both structures takes approximately 15 days to complete.The major point of difference between the two buildings is the method of construction used.The use of the balloon construction method means that the Timber structure only placesvertical members in two lifts during construction, compared to the Concrete structure whichmust place wall and column members at each floor. The Concrete assembly negates this issueby using pre-fabricated members containing both column and beam elements, and as lessmembers are required on each floor, a similar time can be achieved.A direct comparison between the two construction times shows little difference in timemeaning that comparable construction times can be achieved with the proposed posttensionedtimber construction.