James_Gleeson
Structural
- Jul 10, 2023
- 10
Hey guys what are the key considerations for designing a stair tread which is supported by a single hollow section central stringer.
-Do you design the tread as a cantilever that is fixed to the stringer?
-What loads, load combinations and deflection limits are to be considered?
-Is 2.7kn point load at the end of the cantilevered tread and 2kpa UDL in accordance with AS1170.1 Table 3.1 appropriate?
-Should we consider the balustrade horizontal loading (say 0.6kn top edge loading - as1170.1 T3.3) which results in a point moment being developed at the end of the cantilevered tread?
-Is span/300 an acceptable deflection limit or is it more appropriate to consider an absolute deflection (max 5mm?)
-I have ran a check on the balustrade loading affects on the tread (steel plate component only) which results in a 0.6knm moment being generated at the edge of the stair tread (assuming cantilever length is 0.6m for a 1.2m wide tread and steel plate is 195mmx10mm) and the deflection is 24mm for permanent and short term load combo (600/24 = deflection limit of 25). Indicating that I need to reduce the cantilever span and thicken up the steel plate, does this sound normal because all photos of these stair configurations I see online do not appear to require plates much thicker than 10mm and they all look to cantilever approx 500mm?
-Is it reasonable to consider the combined I and Z of the timber and steel component of the tread for deflection and strength checks or alternatively is it better to utilise a thick bit of timber to resolve the loads rather than the steel plate?
Thanks guys, anything you can provide would be appreciated.
-Do you design the tread as a cantilever that is fixed to the stringer?
-What loads, load combinations and deflection limits are to be considered?
-Is 2.7kn point load at the end of the cantilevered tread and 2kpa UDL in accordance with AS1170.1 Table 3.1 appropriate?
-Should we consider the balustrade horizontal loading (say 0.6kn top edge loading - as1170.1 T3.3) which results in a point moment being developed at the end of the cantilevered tread?
-Is span/300 an acceptable deflection limit or is it more appropriate to consider an absolute deflection (max 5mm?)
-I have ran a check on the balustrade loading affects on the tread (steel plate component only) which results in a 0.6knm moment being generated at the edge of the stair tread (assuming cantilever length is 0.6m for a 1.2m wide tread and steel plate is 195mmx10mm) and the deflection is 24mm for permanent and short term load combo (600/24 = deflection limit of 25). Indicating that I need to reduce the cantilever span and thicken up the steel plate, does this sound normal because all photos of these stair configurations I see online do not appear to require plates much thicker than 10mm and they all look to cantilever approx 500mm?
-Is it reasonable to consider the combined I and Z of the timber and steel component of the tread for deflection and strength checks or alternatively is it better to utilise a thick bit of timber to resolve the loads rather than the steel plate?
Thanks guys, anything you can provide would be appreciated.