Structural Analysis and Design of Concrete Tall Buildings: Efficiency and Effectiveness

Tarek Hassan
Senior Associate - Head of Design Unit
Dar al-Handasah Shair & Partners, Cairo

Tall building developments have been rapidly increasing worldwide. Structural material systems for high-rise buildings should be chosen by carefully considering architectural, economical and site factors. The cost of the material, technological expertise and the way that tall buildings are being built all influence material selection of tall buildings. This presentation reviews the evolution of tall building’s structural systems and materials during the past 20 years. Preferences and the economic viability of the different structural materials that are used in tall buildings’ construction are discussed. Different load transfer mechanisms are presented. While most representative structural systems for tall buildings are discussed, the emphasis in this presentation is on current trends such as outrigger systems, its preferable locations and arrangements. Special emphasis in this presentation is given to the shear capacity and behavior of coupling beams which are normally used in tall buildings to interconnect the structural walls to safely resist the applied lateral loads. Non-linear finite element analyses were performed to compare the predicted behavior to that estimated using current design codes. Results of the analysis showed that the use of the deep beam design method provisions in codes leads to very conservative shear designs compared to finite element analysis. The presentation also provides some shades on the creep behavior of high strength concrete with compressive strengths range from 65 to 85 MPa based on test results. The results are compared to generally accepted creep analytical models.