Tuned mass dampers (TMDs) are considered as the most common control devices used for protecting high-rise buildings from vibrations. Because of their simplicity and efficiency, they have found wide practical applications in high-rise buildings around the world. This paper proposes an innovative technique for using partial floor loads as multiple TMDs at limited number of floors. This technique eliminates complications resulting from the addition of huge masses required for response control and maintains the mass of the original structure without any added loads. The effects of using partial loads of limited floors starting from the top as TMDs on the vibration response of buildings to wind and earthquakes are investigated. The effects of applying the proposed technique to buildings with different heights and characteristics are also investigated. A parametric study is carried out to illustrate how the behavior of a building is affected by the number of stories and the portion of the floor utilized as TMDs. Results indicate the effectiveness of the proposed control technique in enhancing the drift, acceleration, and force response of buildings to wind and earthquakes. The response of buildings to wind and earthquakes was observed to be more enhanced by increasing the story-mass ratios and the number of floor utilized as TMDs. ª 2015 The Author. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

As PT floor slabs become thinner, a doubt about its vibration behavior and comfort of occupants arises. This paper investigates several approaches for determining the post-tensioned slabs behavior for human induced vibrations which can give a high accuracy for determining the vibration behavior and can be considered as a simple tools and a guide for designers. It also studies the vibration behavior of slabs with different span length, and thicknesses and relates vibration response to natural frequency of floor. The results show that the frequency of the slab is increased by decreasing the span length or increasing the slab thickness. The peak acceleration is mainly decreased achieving acceptable vibration behavior by increasing the slab thickness to length ratio for all span lengths studied. The results also indicate that PT floor slabs with practical thickness-span ratios and designed for deflection are expected to be acceptable for vibration. The limits of natural frequency for vibration validity of floors are also discussed.

Post tensioned "PT "floors are one of the most widely used systems for building construction all over the world. Such systems have too many behavior, construction and economic benefits over other systems used for relativitely long span floor system . In Egypt, the use of PT systems still has market and economic constraints related to practice and leading to very limited use of such superior system. This paper aims at investigating in-depth the different merits of PT systems considering behavior, design, construction and economic issues. In addition a numerical study for comparison of the costs with the RC flat slab constructio which is the most commonly used system in the Egyptian market. Economic span of PT systems and the saving in concrete, rebar costs as balanced to the additional PT strands, ducts and accessoriness's are investigated. Results indicated the advantages of using PT floor systems especially for relatively large spans and multistory construction where time plays an important role. Spans more than 8.3 meters, PT sy proved to be more economic according to the Egyptitian market practice. This economic span becomes slightly less in case of more live loads.