Journal of Structural and Construction Engineering

Journal of Structural and Construction Engineering

The effect of shell versus membrane modeling of concrete slab on the nonlinear behavior of intermediate moment frames

Document Type : Original Article

Authors
Mostafa Zare Shahneh 1
Mohammad Reza Mirjalili 2
1 MSc student, Civil Engineering department,, Yazd University, Yazd, Iran
2 Civil engineering department, Yazd University, Yazd, Iran
10.22065/jsce.2024.412188.3198
Abstract
In the seismic analysis and design of lateral bearing systems, the contribution of slab bending stiffness is ignored due to its low ductility. So that the lateral bearing system must be able to resist the full seismic load without considering the capacity of the slab. In order to mention this concern in the structural models, it is necessary to consider the bending stiffness of the slab very small or to use the membrane behavior modeling for the slab. This decision will cause the slab's bending capacity be unintentionally discounted under gravity loads which leads to uneconomical structural design. Regarding the slab contribution in analysis or not, in any case, in the earthquake the slab absorbs a part of seismic loads and neglecting its behavior may cause some misleading results. In this paper, the effect of modeling approaches of concrete slabs on the seismic behavior of intermediate moment frames is investigated. For this purpose, several concrete moment frames are designed and modeled with different values of the beam to slab bending stiffness ratio for one, three and five story buildings. The results show that the modeling of slab with shell behavior causes a decrease of about 10% in the R-factor of the structure. On the other hand, in membrane models the R-factor of the structure has increased by about 10%. Therefore, as a practical design procedure for the low and mid-rise concrete intermediate moment frames which the contribution of seismic demands in beam members is not large in comparison with gravity demands, the shell modeling for slab members is proposed while the lateral system R-factor be considered as R=4.5.
Keywords
Concrete slab
shell
membrane
nonlinear behavior
ductility
R-factor

Subjects

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  • Receive Date 28 August 2023
  • Revise Date 13 December 2023
  • Accept Date 01 January 2024