Another problem is people pulling 3kN/m crowd load out off a hat, without proper reference to the loading code occupancy type classifications given in AS1170.1. The loading of 3kN/m only relates to occupancy type C5, and the description given seldom relates to the building space involved. Though the code does have a requirement to use 3kN/m if there maybe an issue of crowd loading irrespective of the other loading criteria. But there are other loads to be considered besides the top edge loading, so simply referring to a single load is not acceptable.
To put simply, the architects preferences are not being considered by structural engineers when designing the building, and assumptions being made that the balustrade manufacturers and suppliers have solutions. They don't have solutions: the building structure needs to be designed to accommodate the connection requirements of the selected balustrade system. The requirements of the connection will vary depending on the resultant post reactions: which compared to the past are no longer insignificant. If the balustrade requires a 150mm embedment into a concrete slab, than a ultra thin 100mm thick slab is not going to accommodate the balustrade. If don't want to see base plates and anchor bolts, then will also have to screed over.
The other issue is removal of existing balustrades and replacing with higher balustrades and higher loaded. The existing structure may not be able to accommodate the higher post reactions, and the posts may need to be closer than the previous installation. It is therefore important to employ the services of a structural engineer when designing the space and not rely on the balustrade suppliers. The existing structure may need extensive strengthening before it is suitable for the desired balustrade.
However, realising that there are about 5 load cases to be considered and otherwise need a quick means of assessing the spacing and height requirements for a given loading, I have been working on a simple program with which to calculate the resultant base moment. It is not intended to provide documented calculations, but allow playing with the desired parameters to see what the main building structure needs to be designed for: so that a suitable structure becomes available to the balustrade suppliers to attach to.
