Presence of infill walls in the frames alters the behaviour of the building under lateral loads. However, it is common industry practice to ignore the stiffness of infill wall for analysis of framed building. Engineers believe that analysis without considering infill stiffness leads to a conservative design. But this may not be always true, especially for vertically irregular buildings with discontinuous infill walls. Hence, the modelling of infill walls in the seismic analysis of framed buildings is imperative. Indian Standard IS 1893: 2002 allows analysis of open ground storey buildings without considering infill stiffness but with a multiplication factor 2.5 in compensation for the stiffness discontinuity. As per the code the columns and beams of the open ground storey are to be designed for 2.5 times the storey shears and moments calculated under seismic loads of bare frames (i.e., without considering the infill stiffness). However, as experienced by the engineers at design offices, the multiplication factor of 2.5 is not realistic for low rise buildings. This calls for an assessment and review of the code recommended multiplication factor for low rise open ground storey buildings. Therefore, the objective of this thesis is defined as to check the applicability of the multiplication factor of 2.5 and to study the effect of infill strength and stiffness in the seismic analysis of low rise open ground storey building.
Infill walls can be modelled in commercial software using two-dimensional area element with appropriate material properties for linear elastic analysis. But this type of modelling may not work for non-linear analysis since the non-linear material properties for a two-dimensional orthotropic element is not very well understood. Seismic evaluation of an existing reinforced concrete (RC) framed building would invariably require a non-linear analysis. Published literature in this area recommends a linear diagonal strut approach to model infill wall for both linear (Equivalent Static Analysis and Response Spectrum Analysis) and nonlinear analyses (Pushover Analysis and Time History Analysis). 
An existing RC framed building (G+3) with open ground storey located in Seismic Zone-V is considered for this study. This building is analyzed for two different cases: (a) considering both infill mass and infill stiffness and (b) considering infill mass but without considering infill stiffness. Two separate models were generated using commercial software SAP2000. Infill weights were modelled through applying static dead load and corresponding masses considered from this dead load for dynamic analyses. Infill stiffness was modelled using a diagonal strut approach. Two different support conditions, namely fixed end support condition and pinned end support condition, are considered to check the effect of support conditions in the multiplication factors. Linear and non-linear analyses were carried out for the models and the results were compared. 
The analysis results show that a factor of 2.5 is too high to be multiplied to the beam and column forces of the ground storey of low-rise open ground storey buildings. This study conclude that the problem of open ground storey buildings cannot be identified properly through elastic analysis as the stiffness of open ground storey building and a similar bare-frame building are almost same. Nonlinear analysis reveals that open ground storey building fails through a ground storey mechanism at a comparatively low base shear and displacement and the mode of failure is found to be brittle. Linear and nonlinear analyses show that support condition influences the response considerably and can be an important parameter to decide the force amplification factor.

/pdf/earthquake-resistant-design-of-low-rise-open-ground-storey-27hvbnvog5.pdf

Earthquake resistant design of low-rise open ground storey framed building

In the seismic analysis of a framed building with masonry infill walls, it is necessary to model the effect of the walls on the lateral stiffness, strength and ductility of the building. The equivalent strut method is convenient for modelling the walls in a large building. However, an appropriate axial load versus deformation relationship for the strut is required in a nonlinear static method of seismic analysis, such as the pushover analysis. The present study proposes a nonlinear axial hinge property for the strut, with suitable performance levels. First, the equivalent strut method and the suitability of two approaches available in the literature for modelling the properties of the struts, are briefly discussed. Next, the nonlinear axial load versus deformation relationship is developed based on experimental data compiled from the literature. The parabolic–plastic relationship is idealized as a tri-linear axial hinge property, so that it can be incorporated in commercial software for undertaking pushover analysis. Next, the use of the hinge property is demonstrated in the pushover analyses of two framed reinforced concrete buildings. The pushover curves based on the proposed hinge property shows improved modelling of the inelastic drifts of the buildings. Although the modelling of a wall using a single strut has limitations, the proposed methodology is practical for a pushover analysis of a building.

Equivalent Strut Method for the Modelling of Masonry Infill Walls in the Nonlinear Static Analysis of Buildings

Presence of infill walls in the frames alters the behaviour of the building under lateral loads. However, it is common industry practice to ignore the stiffness of infill wall for analysis of framed building. Engineers believe that analysis without considering infill stiffness leads to a conservative design. But this may not be always true, especially for vertically irregular buildings with discontinuous infill walls. Hence, the modelling of infill walls in the seismic analysis of framed buildings is imperative. Indian Standard IS 1893: 2002 allows analysis of open ground storey buildings without considering infill stiffness but with a multiplication factor 2.5 in compensation for the stiffness discontinuity. As per the code the columns and beams of the open ground storey are to be designed for 2.5 times the storey shears and moments calculated under seismic loads of bare frames (i.e., without considering the infill stiffness). However, as experienced by the engineers at design offices, the multiplication factor of 2.5 is not realistic for low rise buildings. This calls for an assessment and review of the code recommended multiplication factor for low rise open ground storey buildings. Therefore, the objective of this thesis is defined as to check the applicability of the multiplication factor of 2.5 and to study the effect of infill strength and stiffness in the seismic analysis of low rise open ground storey building. Infill walls can be modelled in commercial software using twodimensional area element with appropriate material properties for linear elastic analysis. But this type of modelling may not work for non-linear analysis since the non-linear material properties for a two-dimensional orthotropic element is not very well understood. Seismic evaluation of an existing reinforced concrete (RC) framed building would invariably require a nonlinear analysis. Published literature in this area recommends a linear diagonal strut approach to model infill wall for both linear (Equivalent Static Analysis and Response Spectrum Analysis) and nonlinear analyses (Pushover Analysis and Time History Analysis). An existing RC framed building (G+3) with open ground storey located in Seismic Zone-V is considered for this study. This building is analyzed for two different cases: (a) considering both infill mass and infill stiffness and (b) considering infill mass but without considering infill stiffness. Two separate models were generated using commercial software SAP2000. Infill weights were modelled through applying static dead load and corresponding masses considered from this dead load for dynamic analyses. Infill stiffness was modelled using a diagonal strut approach. Two different support conditions, namely fixed end support condition and pinned end support condition, are considered to check the effect of support conditions in the multiplication factors. Linear and non-linear analyses were carried out for the models and the results were compared. The analysis results show that a factor of 2.5 is too high to be multiplied to the beam and column forces of the ground storey of low-rise open ground storey buildings. This study conclude that the problem of open ground storey buildings cannot be identified properly through elastic analysis as the stiffness of open ground storey building and a similar bare-frame building are almost same. Nonlinear analysis reveals that open ground storey building fails through a ground storey mechanism at a comparatively low base shear and displacement and the mode of failure is found to be brittle. Linear and nonlinear analyses show that support condition influences the response considerably and can be an important parameter to decide the force amplification factor.

http://www.ijirt.org/master/publishedpaper/IJIRT144417_PAPER.pdf

The presence of walls on the dashboard changes the behavior of the building on a more general basis. However, it is common practice for companies to ignore the possibility of wall erosion for the details of the building being built. Engineers believe that analysis without looking at constraints is what improves design. But this may not always be true, especially for low-cost homeowners without using it. Therefore, the design of the walls in the integrated architectural design is crucial. ISI 1893: 2002 allows warehouse storage without regard to energy constraints, but with an increase of 2.5 versus consumption. According to the schedule, vacant flyer posts and markings should be designed up to 2.5 times the store's sales and schedules according to the non-slip layout (i.e. without driving force). However, as engineers know in design agencies, the size factor of 2.5 is not realistic for low-rise buildings. This requires revision and revision of the special rule that has proposed much of the rationale for low-income housing. Therefore, the aim of this study is defined as checking the use of factor 2.5 and investigating the effect of energy efficiency and stress on the post-diffusion model Home theater industry. A building built on RC (G + 3) with landfills located in the seismic zone - V is designed for this study. This building has been analyzed for two different issues: (a) consideration of body weight and weight and (b) consideration of material damage without consideration of strength. Two types of templates were used with SAP2000 software. Weight loss using mean weighted weight and similar devices evaluated from this death test was analyzed for durability analysis. Similar to eliminating pressure using a sequential method.

Seismic Design at Low Altitude, Building Built on the Playground

Today in the world of concrete we are rapidly constructing multi-storey building for commercial and residential purposes, but providing a proper parking space is major concern especially in metropolitan cities. Hence the trend has been utilize the basement of building for parking purpose for this engineer provides the solution they make the basement of the building open, no infill masonry walls is provided in the basement .they did not consider the stiffness and strength of the masonry wall .But this conservative design is not always right .We see when the earthquake occur the column of the ground storey collapse down and the upper storey inclined towards the ground because the upper stories are more stiffer than the lower storey. This failure is termed as soft storey effect because ground storey is more flexible in comparison of upper stories. Open ground storey is also known as weak stories because it is also weaker in strength in comparison of upper stories .After the Bujh Earthquake in Gujarat, India the failure of upper stories emphasis to consider the strength and stiffness of the infill masonry .Therefore IS Code 1893:2002 suggests that we need not to consider the strength of infill masonry but simply consider a factor 2.5 which is known as the multiplication factor for the neutralization the effect of soft storey. It is in clause 7.10.3 (A) of IS 1893:2002 that the beams and columns of the storey need to be taken 2.5 times more the storey shear and moments calculated under specific loads of the bare frame. Nonetheless, by the expertise of the structural design the value suggested by IS CODE 1893:2002 is not realistic. For the validation of the multiplication factor we prepare a separate model for infill wall and walls without any infill i.e. bare frame, and do the linear and nonlinear analysis and compare their results. Linear analysis shows stiffness is constant in both open ground storey and bare frame while non-linear shows the multiplication factor can be reduced.

https://www.jetir.org/papers/JETIR1603009.pdf

A. Asokan

Papers

Modelling of masonry infill walls for nonlinear static analysis of buildings