International Journal of Engineering Research ISSN:2319-6890)(online),2347-5013(print) Volume No.4, Issue No.11, pp : 631-634 01 Nov. 2015 IJER@2015 Page 631 Effect of Vertical Irregularities of RC Framed Structures by Using Non-Linear Static Analysis 1 Sri.M.Pavan Kumar, 2 Sateesh Konni, 1 Dept. of Civil Engineering, SVP College of Engineering, Andhra University, AP, India 2 Dept. of Civil Engineering, SVCET, JNTU-K, AP, India Abstract : Major structural collapses occur when a building is under the action of Dynamic Loads which includes both Earthquake and Wind loads. In these modern days, most of the structures are involved with architectural importance and it is highly impossible to plan with regular shapes. These irregularities are responsible for structural collapse of buildings under the action of dynamic loads. Hence, extensive research is required for achieving ultimate performance even with a poor configuration. In the present work, “Effect Of Vertical Irregularities of RC framed Structures by Using Non- Linear Static Analysis”, considering four types of 10- Storied 3-D frames (i.e., a symmetrical elevation configuration throughout its height and three other frames with unsymmetrical vertical configuration starting from sixth floor, placed at corner, at the center and at edge of the plan respectively) it is focused to study their response using Non- Linear Static Analysis. From the studied results of the analysis of four frames, it is observed that in the regular frame, there is no tensional effect in the frame because of symmetry. The response for vertically irregular buildings is different for the columns which are located in the plane perpendicular to the action of force. This is due to the tensional rotation in the structure. Keywords : Earthquake, Response, Non-Linear, Vertical I. Introduction A building is said to be a regular when the building configurations are almost symmetrical about the axis and it is said to be the irregular when it lacks symmetry and discontinuity in geometry, mass or load resisting elements. Asymmetrical arrangements cause a large torsion force. IS 1893: 2002 (part1) has explained building configuration system for better performance of RC buildings during earthquakes. The building configuration has been described as regular or irregular in terms of the size and shape of the building, arrangement of structural the elements and mass. There are two types of irregularities 1) Horizontal irregularities refers to asymmetrical plan shapes (L, T, U and F) or discontinuities in horizontal resisting elements such as re-entrant corners, large openings, cut outs and other changes like torsion, deformations and other stress concentrations, 2) Vertical irregularities referring to sudden change of strength, stiffness, geometry and mass of a structure in vertical direction. The main objective of the present work is to study the response of the irregular structures under dynamic loads. In this present study it is proposed to consider the building frames that are irregular in elevation and analyze the response and behavior of the structures under earthquake. For this purpose, four RC building frames are selected and it is proposed to analyze all the frames that are considered and are modeled. ETABS analysis package is proposed for the analysis of all structures, to get the all nodal displacements. Frames considered in this study are 10- Storied 3-D frames with symmetrical elevation configuration throughout its height and three other frames with unsymmetrical vertical configuration starting from sixth floor, placed at corner, at the center and at edge of the plan respectively as shown in Figure 1. It is proposed that the responses of all the above frames are to be determined for all the load combinations. Lateral loads and Storey shears of all the four frames due to earthquake loads is proposed to determine using Non-linear static analysis method. Fig. 1: Frames of Different Configuration (1, 2, 3 and 4) II. Modeling The analysis of frames with different vertical irregularities is to be performed. For this purpose, four frames are selected as shown in Figure 1. Frame-1 is a regular frame that consists of ten storey’s with a symmetrical plan configuration of square shape provided with 4 x 4 bays as shown in Figure 1 and is considered whose centre of mass coincides with the centre of rigidity. Three other frames (4 x 4 bays up to sixth floor and 2 x 2 bays from sixth floor to tenth floor) with unsymmetrical vertical configuration starting from tenth floor, placed at corner, at the center and at edge of the plan respectively are also considered. All these are 10-storied building frames with floor heights of 3m except ground floor and bay size of 4m x 4m.height of ground floor is 2m and the total height of the all building frames is 22m ( Figure 2 ) . As per IS code 1893 -2002, the natural time period is 2.025 sec. Number of members, nodes and supports of all four building frames are given in the Table 1. Material properties considered for the analysis using ETABS are given in the Table 2. Physical properties of members selected for the analysis are given in the Table 3. Dead load and Live loads considered for the analysis are given in Table 4. Earthquake