s arabi - PhD Candidate faculty of architecture, University of Tehran, Tehran, Iran,
m.r darabpour - PhD Candidate department of Civil Engineering, Azad University, Central Branch
m Mohammadkhani - MSc, faculty of architecture, Shahid Beheshti university, Tehran Iran

Construction of every structure consists of constructing the foundation, columns, walls and slabs. The most time consuming part in the analysing time of the projects is construction of the slabs. Fifty percent of time of the projects, especially mega structures like mega malls are allocated to construction of the slabs. Ways which can reduce this duration will reduce the cost of the projects as well. It is obvious if the client of the project can operate the project any sooner it will help him to save big amount of money. This condition is more highlighted in Middle Eastern countries like Iran because of the uncertainty and the inflation found in their market. This article focused on the role of precast concrete (hollow cores) to validate this theory that using this system of construction will help to reduce the cost and time of the projects. In this article we used the expert s opinion working in two different mega malls, one used this system and the other did not. The results show the efficiency of utilizing hollow-core system and its benefits. Expanding experience through these case studies, the method to estimate the influence of using hollow-cores in cost and time of the projects, the considerations should be observed to use the hollow-cores in its best shape is the main purpose of this article. The more the building area exists the more we can sense the effectiveness of this structural system.

Cost, time, hollow-core, mega structures