A Simple Approach for the Design of Ductile Earthquake-Resisting Frame Structures Counting for P-Delta Effect
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Department of Architecture, Built Environment and Construction Engineering, Politecnico Di Milano, 20133 Milan, Italy
2
Department of Civil and Environmental Engineering, Politecnico Di Milano, 20133 Milan, Italy
3
Department of Civil Engineering, EPOKA University, 1000 Tirana, Albania
*
Author to whom correspondence should be addressed.
Buildings 2019, 9(10), 216; https://doi.org/10.3390/buildings9100216
Received: 9 July 2019 / Revised: 24 September 2019 / Accepted: 29 September 2019 / Published: 8 October 2019
In the last decades, the possibility to use the inelastic capacities of structures have driven the seismic design philosophy to conceive structures with ductile elements, able to obtain large deformations without compromising structural safety. In particular, the utilization of high-strength elements combined with the purpose of reducing inertial masses of the construction has highlighted the second-order effect as a result of the “lightweight” structure’s flexibility. Computational aspects of inclusion of the second-order effects in the structural analysis remain an open issue and the most common method in the current design practices uses the stability coefficient The stability coefficient estimates the ratio between the second-order effect and lateral loads’ effects. This coefficient is used then to amplify the lateral loads’ effects in order to consider the second-order effects, within a certain range proposed by codes of practices. In the present paper, we propose a simple approach, as an alternative to the stability coefficient method, in order to take into consideration P-Delta effects for earthquake-resisting ductile frame structures in the design process. The expected plastic deformations, which can be assessed by the behavior factor and the elastic deformations of the structure, are expected to magnify the P-Delta effects compared to those estimated from an elastic approach. The real internal forces are approximated by modifying the stiffness matrix of the structure in such a way as to provide a compatible amplification effect. This concept is herein implemented with a three-step procedure and illustrated with well-documented case studies from the current literature. The obtained results show that the method, although simple, provides a good approximation compared to more refined and computationally expensive methods. The proposed method seems promising for facilitating the design computations and increasing the accuracy of the internal forces considering the second-order effects and the amplification from the inelastic deformations.
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Keywords:
P-Delta; steel structures; seismic design; ductility; behavior factor; stability coefficient
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MDPI and ACS Style
Shehu, R.; Angjeliu, G.; Bilgin, H. A Simple Approach for the Design of Ductile Earthquake-Resisting Frame Structures Counting for P-Delta Effect. Buildings 2019, 9, 216. https://doi.org/10.3390/buildings9100216
AMA Style
Shehu R, Angjeliu G, Bilgin H. A Simple Approach for the Design of Ductile Earthquake-Resisting Frame Structures Counting for P-Delta Effect. Buildings. 2019; 9(10):216. https://doi.org/10.3390/buildings9100216
Chicago/Turabian StyleShehu, Rafael; Angjeliu, Grigor; Bilgin, Huseyin. 2019. "A Simple Approach for the Design of Ductile Earthquake-Resisting Frame Structures Counting for P-Delta Effect" Buildings 9, no. 10: 216. https://doi.org/10.3390/buildings9100216
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