Estağfurullah sn.cakilomer, There is no definite rule for the direction of the ribs, it should be done as the system requires. The deflection of the ribs affects the load on the beam. If there is a weak beam, it should be run parallel to it, for example, if the system is available. Apart from this, it is healthier for the system to have the same rib direction in the ongoing floors. It is also necessary to consider the ease of application. It is not always good to do it in the short direction. Good work