International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 02 | Feb -2017
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e-ISSN: 2395 -0056 p-ISSN: 2395-0072
SEISMIC ANALYSIS OF REINFORCED CONCRETE BUILDINGS -A REVIEW Krishna G Nair1, Akshara S P2 1PG
Student, Department of Civil Engineering, FISAT, Angamaly, India Professor, Department of Civil Engineering, FISAT, Angamaly, India
2Assistant
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Abstract - The response of building when subjected to
ductility, stiffness, damping and mass. The design can be divided into two main steps. First, a linear analysis is conducted with dimensioning of all structural elements, ensuring the functionality of the structure after minor earthquakes, and then the behaviour of structures during strong earthquakes has to be conducted using nonlinear methods. Dynamic analysis should be performed for symmetrical as well as unsymmetrical buildings. In unsymmetrical building structures the major parameter to be considered is Torque.
seismic excitation can be evaluated in a number of ways. Structural analysis methods can be mainly divided into four categories Equivalent Static Analysis, Linear dynamic analysis, Nonlinear Static Analysis, Nonlinear dynamic analysis. Equivalent Static Analysis method or linear static analysis, defines a series of forces acting on a building to represent the effect of earthquake ground motion. In this method, the design base shear is computed for the whole building, and it is then distributed along the height of the building. The response spectrum analysis determines the natural frequencies and mode shapes via eigen value analysis. It is used to estimate the peak response whereas the time history analysis provides a method for obtaining the exact response of a structure as a function of time. The response-history is normally determined using step by step numerical integration of the equation of motion. Nonlinear Static Analysis is also known as pushover analysis. A pattern of forces is applied to a structural model that includes non-linear properties (such as steel yield), and the total force is plotted against a reference displacement to obtain a capacity curve. In nonlinear dynamic analyses, the detailed structural model subjected to a ground-motion record produces estimates of component deformations for each degree of freedom in the model.
2. SEISMIC ANALYSIS OF STRUCTURE For the determination of seismic responses it is necessary to carry out seismic analysis of the structure. The analysis can be performed on the basis of external action, the behaviour of structural materials, structure and the type of structural model selected. Based on the type of external action and behaviour of structure, the analysis can be further classified as: (1) Linear Static Analysis (2) Nonlinear Static Analysis (3) Linear Dynamic Analysis (4) Nonlinear Dynamic Analysis
2.1 Linear Static Analysis
Key Words: Dynamic Analysis, Base shear, Seismic forces, Pushover analysis, Time history
This method is also known as Equivalent Static Analysis method. This procedure does not require dynamic analysis, however, it account for the dynamics of building in an approximate manner. The static method is the simplest one among all the other analysis procedures. It requires less computational efforts and is based on formulas given in the code of practice. First, the design base shear is computed for the entire building and it is then distributed along the height of the building. The lateral forces at each floor levels thus obtained are distributed to individual lateral load resisting elements. The equivalent static analysis procedure involves the following steps: Calculation of the Design Seismic Base Shear, VB Vertical distribution of base shear along the height of the structure Horizontal distribution of the forces across the width and breadth of the structure Determination of the drift and overturning moment
1. INTRODUCTION All over the world, there is a high demand for construction of tall buildings due to increasing urbanization and spiraling population, and earthquakes have the potential for causing the greatest damages to tall structures. Reinforced concrete multi-storied buildings are very complex to model as structural systems for analysis. Usually, they are modeled as two-dimensional or three-dimensional frame systems using finite beam elements. Since earthquake forces are random in nature and unpredictable, the engineering tools need to be sharpened for analysing structures under the action of these forces. Earthquake loads are required to be carefully modeled so as to assess the real behaviour of structure with a clear understanding that damage is expected but it should be regulated. Analysing the structure for previous earthquakes of different intensities and checking for multiple criteria at each level has become essential and pivotal these days. The main parameters to be checked in the seismic analysis of structures are load carrying capacity,
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