Hello all,
I have a two storey building - with concrete walls on two sides extending up to roof level. The lateral system at first floor in one direction is steel frames supporting the panels in one direction and a roof bracing truss distributing loads to walls/braced frames in the other direction. Ground floor lateral structure is mostly concrete walls. The roof structure is roof purlins (flexible).
I am wanting to distribute the seismic loads into the upper frames by tributary width, but it appears to be treating my roof as rigid with the stiff walls still receiving majority of the load.
How do I make a flexible diaphragm so the loads are applied by tribitary not stiffness? I have defined the roof as planks with 1E-3 membrane stiffness.
I have a two storey building - with concrete walls on two sides extending up to roof level. The lateral system at first floor in one direction is steel frames supporting the panels in one direction and a roof bracing truss distributing loads to walls/braced frames in the other direction. Ground floor lateral structure is mostly concrete walls. The roof structure is roof purlins (flexible).
I am wanting to distribute the seismic loads into the upper frames by tributary width, but it appears to be treating my roof as rigid with the stiff walls still receiving majority of the load.
How do I make a flexible diaphragm so the loads are applied by tribitary not stiffness? I have defined the roof as planks with 1E-3 membrane stiffness.