Vertical shortening prediction for super‐tall buildings considering enclosure effect and coupling effect

Abstract

In this paper, the time-dependent vertical shortening behavior of the super-tall building is studied considering the enclosure effect and the coupling effect. A combined method to predict the overall strain of the mega section is firstly proposed by combining the B3 model and the fiber modeling approach to consider the enclosure effect of mega steel and validated by a series of in-house experiments. An iteration method is then proposed based on the construction sequence method to consider the coupling effect of stress and strain in the vertical shortening prediction and illustrated by a super-tall building project. Finally, the vertical shortening predictions of the super-tall building project are compared with the field monitoring records. The resultsshow that the strain predictions by the combined method show good agreement with experiments. Without considering the enclosure effect, the overall strain of mega section is overestimated. The coupling effect affects more on the vertical shortening of the mega column than on that of the shear wall and more on the elastic shortening than on the inelastic shortening. Without considering the coupling effect, the elastic shortening is significantly underestimated in the mega column but slightly overestimated in the shear wall. The predictions of vertical shortening in the shear wall show reasonable agreement with the measurements, whereas those in the mega column show large disagreement with the measurements, which enlightens the necessity to improve the prediction method further. KEYWORDS a combined method, an iteration method, coupling effect, enclosure effect, super-tall building, vertical shortening | INTRODUCTIONIn the past decades, the outrigger structural system has proven to be an efficient lateral stiffness system to reduce the lateral drift under the wind or seismic loading and widely adopted in super-tall buildings. However, this structural system suffers from the excessive stress to the structural members under the time-dependent actions, such as the shrinkage and creep. Vertical shortening is one of the major considerations in the design and construction of super-tall buildings. The differential vertical shortening could cause adverse effects on the nonstructural elements of buildings, such as the curtain walls, partitions, electrical pipelines, and elevators and may also result in redistribution of structural member forces.The vertical shortening prediction of super composite components mainly contains two aspects. The one is the model utilized to predict shrinkage and creep, which is kind of material-level issue, whereas the other one is related to the structure-level issue, that is, how to deal with the composite structural components. Shrinkage and creep are the natural characteristics of concrete along with the formation, the development, and

A comparative study on the differential axial shortening in high‐rise buildings

“…Nonstructural elements such as partitions, finishes, ceilings, façades elements, or plumbing can be damaged 20,21 and a stress redistribution can occur from the shortest element to the more rigid one. 22 Throughout the conceptual stage of a project, it is possible to minimize the effects that DAS will cause over the lifetime of a building. Maru et al 23 studied DAS mitigation thanks to the installation of stiff beams connecting columns and core.…”

“…On the contrary, once the construction of the building is completed, the effects due to sub‐to shortening DASs are inevitable. Nonstructural elements such as partitions, finishes, ceilings, façades elements, or plumbing can be damaged 20,21 and a stress redistribution can occur from the shortest element to the more rigid one 22 …”