International Research Journal of Engineering and Technology (IRJET)
Volume: 04 Issue: 02 | Feb-2017
e-ISSN: 2395 -0056 p-ISSN: 2395-0072
www.irjet.net
INFLUENCE OF P-DELTA EFFECT ON REINFORCED CONCRETE BUILDINGS WITH VERTICAL IRREGULARITY - A REVIEW Lakshmi Subash 1, Sruthi K Chandran 2 1PG
Student, Department of Civil Engineering, Sreepathy Institute of Management And Technology, Vavanoor, Kerala, India 2 Assistant Professor, Department of Civil Engineering, Sreepathy Institute of Management And Technology, Vavanoor, Kerala, India
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract – In modern multi-storied building construction, irregular type buildings (with irregularity in plan and elevation) are commonly increasing, mainly because of architectural aesthetics and functional requirements. Such types of construction will be highly fragile buildings in seismological sensitive areas. Inappropriate design of these irregular buildings leads to abrupt destruction of the structures; hence it requires special consideration in analysis and design. The additional action in the structure due to the structural deformation by virtue of the applied loads is termed as P-delta effect. P-Delta is a non-linear effect that occurs in every structure where elements are subject to axial load. Due to little knowledge of P-Delta and complexity of analysis, architectures and structural engineers are tempted to perform linear static analysis, which may eventually become the cause of a sudden collapse of the structure. In the case of short columns and medium rise structures, P-delta effect will be small and hence negligible. But in slender columns or high rise structures, P-delta effect becomes more significant. In the design of high rise buildings with vertical irregularity, it is very much important to examine whether the second order P-delta effects are significant.
and the building characteristics. It also depends upon the height, stiffness and asymmetry of the building. Building asymmetry leads to imbalances in distribution of mass, stiffness ,etc. Buildings constructed without considering the second order P-Delta effect and appropriate characteristic seismic resistance constitute the main source of risk during an earthquake.
Key Words: P-Delta effect, Irregular buildings, slender column, High rise structure. Fig.1: Structural collapse due to effect of P-delta
1 INTRODUCTION In the recent years Earthquake is considered to be one of the most destructive or damaging natural calamity. These cause severe damages to lives and properties. Almost all deaths related earthquakes are caused by the collapse of structures. This is the major reason for increasing demand for earthquake-resistant buildings. During an earthquake tall buildings will have a tendency to shake more than short buildings. Moreover, buildings having irregular configuration are more susceptible to severe damages in an earthquake. Unlike regular building, behavior of irregular building is more complex and unpredictable during the course of an earthquake. P-Delta effect, which is a second-order nonlinear effect occurring in every structure where elements are subject to axial load and more prominent in tall buildings. P-Delta effect holds an important role in the analysis of the structure. The P-Delta effect is mainly dependent on the applied loads Š 2017, IRJET
|
Impact Factor value: 5.181
|
2 THEORETICAL BACKGROUND During an earthquake the failure of structure generally starts from the point of the structural weakness present in the building systems. This weakness arises due to discontinuity in mass, stiffness and geometry of structure. The structural weakness generates further structural deterioration which leads to the structural collapse. The structures having these discontinuities are known as Irregular structures. These irregular structures constitute a large portion of the modern urban infrastructure. Vertical irregularities are one of the major reasons of failures of structures during earthquakes. For example structures with soft storey were the most remarkable structures which collapsed. So, the effect of vertically irregularities in the seismic performance of structures becomes really important. The dynamic characteristics of buildings with vertically
ISO 9001:2008 Certified Journal
|
Page 709