Investigation of Creep-Induced Vertical Shortening and Its Influencing Factors in High-Rise Reinforced Concrete Buildings Using Conventional and Time-Dependent Staged Analyses

Articles in Press

Document Type : Research Paper

Authors

1 Structural Engineering Department, Faculty of Civil Engineering, Semnan University, Semnan, Iran.

2 Structural Engineering Department. Faculty of Civil Engineering, Semnan University. Semnan. Iran.

3 Structural Engineering Deparrment. Faculty of Civil Engineering, Isfahan University of Technology, Isfahan, Iran.

4 Earthquake Engineering Department. Faculty of Civil Engineering, Semnan University, Semnan, Iran.

10.22124/jcr.2025.30912.1705

Abstract

Sustained axial and flexural stresses in reinforced concrete members lead to creep strains over time. Controlling flexural deformations caused by creep in horizontal members is a fundamental requirement in structural design. Columns and walls in high-rise reinforced concrete buildings are subjected to sustained compressive forces, resulting in inelastic shortening during service. Differential shortening among vertical members induces additional self‑equilibrating stresses, especially in short horizontal members. Architectural and constructional constraints often necessitate openings near columns, leading to the formation of short link beams in dual structural systems. In such cases, considering the effects of self‑induced stresses in these shear‑dominant link beams becomes crucial. Neglecting creep analysis and its influencing parameters can lead to structural and non‑structural damage during service life. In this study, the stages of creep analysis were first manually described for a two‑dimensional frame and then compared with the results from ETABS software. Subsequently, the effects of construction speed, relative humidity, and concrete strength on the shortening of a 20‑story building were investigated using staged construction analysis. Results showed that creep contributes to horizontal displacements, which can be mitigated through geometric symmetry and gradual section changes along the height. In arid climates, shortening may increase up to 115% compared to humid regions. Doubling concrete strength can reduce shortening by up to 30%, and extending floor construction time from 20 to 40 days can reduce it by 13%. Load distribution and optimized section selection for vertical members adjacent to short link beams play a significant role in managing self‑induced stresses.

Keywords

Main Subjects

Concrete Research

Articles in Press, Accepted Manuscript
Available Online from 06 October 2025

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