Progressive collapse
Story Number < 4 stories
Progressive collapse is not critical. However, the structure should be designed with minimum vertical and horizontal ties and that all connections for beams and columns should be cast monolithically. This is so the RC structure will have adequate reinforcement within to resist and avoid progressive collapse.
For buildings with more than 4 stories, there should be adequate horizontal and vertical ties and an alternative load path should also be designed. All connections should also be cast monolithically.
Cladding
Brickwork or brick cladding –
No need to set back columns since there is no glazing
Perimeter fully glazed –
Columns and slabs should be set back 200mm to cater for cladding or glazing installations and connections.
No external structural walls or columns should be allowed.
Steel truss at roof level
Yes –
Roller supports should be used to allow structural movement caused by thermal expansion
Torsional effect
Yes-
Torsional effect is created by the asymmetric arrangement of core wall. Its effect on the structure should be checked during detail design.
Structural Element to be Exposed
Yes-
In order to provide good appearance, fair face concrete or circular columns will be used and that no false ceiling for slab soffit should be exposed. Fair face concrete or circular columns should be constructed by using special material with high standards of construction care. There should be no external cladding along the external perimeter walls.
No-
There is no need to set back edge columns
Plan Layout?
Open Plan Layout-
Only columns at 5m c/c should be used.
No structural walls should be used.
Column Spacing where _m center to center-
All internal columns, perimeter columns, core walls should be spaced __m center to center
Movement Joint?
MJ for structures with different height
Movement joints should be used to separate the structure into different independent sections in order to prevent differential settlement and stress caused by movement.
Movement joints reduce thermal effect and cracking effect caused by shrinkage.
Movement joints are composed of polythene sheet with bituminous paint, water stop, and joint sealant and are usually 25mm-50mm wide.
MJ for buildings longer than 60m
Movement joints should be used to separate the structure into different independent sections in order to prevent differential settlement and stress caused by movement.
Movement joints reduce thermal effect and cracking effect caused by shrinkage.
Movement joints are composed of polythene sheet with bituminous paint, water stop, and joint sealant and are usually 25mm-50mm wide.
Structures with irregular shapes
Movement joints should be used to separate the structure into different independent sections in order to prevent differential settlement and stress caused by movement.
Movement joints reduce thermal effect and cracking effect caused by shrinkage.
Movement joints are composed of polythene sheet with bituminous paint, water stop, and joint sealant and are usually 25mm-50mm wide.
Preferred no MJs should be used
Shrinkage strips should be used to reduce thermal effects and shrinkage cracking.
For carparks, shrinkage strips should be provided at the middle of the carkpark to reduce shrinkage on large plates of concrete.
Shrinkage strips should be used for basement slabs and swimming pools since movement joints are not allowed in these situations due to shrinkage strips are more effective for substructures in wtaer.
MJ for significant change in foundation load and height of structure
Movement joints should be used to separate the structure into different independent sections in order to prevent differential settlement caused by different types of loads and uses above and stress caused by movement.
Movement joints reduce thermal effect and cracking effect caused by shrinkage.
Movement joints are composed of polythene sheet with bituminous paint, water stop, and joint sealant and are usually 25mm-50mm wide.
Lift Core or Service Core?
Yes-
Lift pit should be considered by assuming its level to be 1.5m – 2m deep below.
Lift machine room should assumed to have a 4m height on roof level. The lift cores should be used to resist lateral loading.
Lighting?
High degree of natural light-
Perimeter should be glazed. Location of perimeter walls or columns should be considered for light paths.
Artificial lighting used-
The structure can have perimeter walls or structural walls at the exterior enclosure.
Roof used as plant area with wall enclosed?
Yes-
The plant room should have lightweight waterproof as its exterior enclosure.
Core Wall Dimensions
Yes-
Core dimensions is to be the external setting out dimension
Parapet Wall at Roof
Yes-
Parapet wall should be designed as 1400mm height
Heaving Effect Negligible
Yes-
This is because the basement or ground floor slab is on top of sand and gravel
Earthquake Load
Yes-
Earthquake loads are not significant in Hong Kong
Elegant structure?
Yes-
Structure should be light in weight, have small member sizes, and have good appearance
Swimming pool?
Yes-
Waterproofing details should be shown, as well as construction approach.
Requires a Fast Construction Programme?
Yes-
Construction methods should be standardized and repetitive.
Flat slabs should be used in order to speed up construction.
Standardized formworks should be used to speed up construction.
