as elevators and fire stairs require more analysis for more economic and efficient solutions of the floor plans in conjunction with the construction of high-rise office buildings in Turkey. ? The cores are interconnected with the main structural frame, thus resisting a substantial amount of the lateral loads in all examples, without exception. This interconnection between the core and the structural frame is provided by the structural floor system and steel outrigger trusses in sample buildings at abroad, whereas examples from Turkey donot utilize any steel outrigger trusses. Utilization of steel outrigger trusses must be supported by designers and contractors of high-rise office developments to improve the efficiency of structural system, thus affecting the size of the structural members.