BEHAVIOUR OF STEEL STRUCTURES IN SEISMIC AREAS (original) (raw)
Related papers
Effect of P-Delta analysis for tall slender building structures
Behaviour of Steel Structures in Seismic Areas (STESSA), Japan, 2006
High-rise buildings are essential in metro cities of developing countries. One of the important aspect of design of tall buildings / frames is to ensure its lateral stability taking care of maximum drift stipulation. This paper includes guidelines stipulated in various codes [such as UBC–Vol. 3 (1997), IS: 800(2007), IS: 1893 (2002 Part-1), etc.] to restrict the P-Delta effect. According to the recent trends for economic limit state design, it is necessary to carry out the nonlinear dynamic analysis in seismic condition for highly ductile material. This also helps to avail advantage of high strength within elastic range. As steel is more ductile than reinforced concrete, geometric non-linearity including stress softening P-Delta effect is an important factor in the design of tall slender steel structures. This also ensures suitability of steel intensive construction including steel-concrete composite construction over the conventional RCC framed construction. Also it requires high end softwares such as STAAD Pro, SAP, ETABS etc. for computation purpose. In the present case STAAD software has been used.
STABILITY ANALYSIS OF STEEL FRAME STRUCTURES: P-DELTA ANALYSIS
The high rise buildings require high frame structure stability for safety and design purposes. This research focused on P-delta analysis to be compared with linear static analysis. In this study, a 18 storey steel frame structure with 68.9 m has been selected to be idealized as multi storey steel building model. The model is analyzed by using STAAD.Pro 2007 structural analysis software with the consideration of P-delta effect. At the same time the influence of different bracing patterns has been investigated. For this reason five types of bracing systems including X, V, Single Diagonal, Double X, K bracing with unbraced model of same configuration are modeled and analyzed. The framed structure is analyzed for Wind load as per IS 875 (part 3)-1987. After analysis, the comparative study is presented with respective to Maximum storey displacement and Axial Force. The present work showed that the 'X'bracing in continuous bracing pattern is proved to be more effective with respect to both Static and P-delta analysis.
Comparative Study of Static and Dynamic Seismic Analysis of A Multistoried Building
Analysis and design of buildings for static forces is a routine affair these days because of availability of affordable computers and specialized programs which can be used for the analysis. On the other hand, dynamic analysis is a time consuming process and requires additional input related to mass of the structure, and an understanding of structural dynamics for interpretation of analytical results. Reinforced Concrete (RC) frame buildings are most common type of constructions in urban India, which are subjected to several types of forces during their lifetime, such as static forces due to dead and live loads and dynamic forces due to earthquake. Here the present study describes the effect of earthquake load which is one of the most important dynamic loads along with its consideration during the analysis of the structure. In the present study a multi-storied framed structure of (G+9) pattern is selected. Linear seismic analysis is done for the building by static method (Seismic Coefficient Method) and dynamic method (Response Spectrum Method) using STAAD-Pro as per the IS-1893-2002-Part-1. A comparison is done between the static and dynamic analysis, the results such as Bending moment, Nodal Displacements, Mode shapes are observed, compared and summarized for Beams, Columns and Structure as a whole during both the analysis.
Lateral Stability Analysis of High Rise Building with the Help of STAAD-PRO
Tall buildings are susceptible to dynamic horizontal loads such as wind and earthquakes. These horizontal forces cause important stresses, displacements and vibrations due to the building's inherent tallness and flexibility. Wind induced displacements and vibrations become critical with increasing height. Excessive displacements can cause damage to partitions, cladding and interior finishes, whereas the human motion perception can induce concern regarding the structural safety and cause nausea and dizziness to the occupants. Analyzing and designing of buildings for static forces is a routine affair these days because of availability of affordable computers and specialized programs which can be used for the analysis. Stiffness and ductility considerations rather than strength would govern the design. The intent in seismic design then is to limit building movements, not so much to reduce perception of motion but to maintain the building's stability and prevent danger to pedestrians due to breakage and falling down of nonstructural elements. In this study, structural systems that can be used for the lateral resistance of tall buildings are classified based on the basic reaction mechanism/structural behavior for resisting the lateral loads. For the reinforced concrete buildings these structural systems are rigid frame systems, Shear-walled frame systems, Outrigger systems, Braced frame systems. In this thesis G+40, G+60, G+80 storied regular building modal has been analyzed by static & dynamic analysis. This building has the plan area of 42.30 m x 18.05 m with a storey height 3.0m and depth of foundation is 2.0 m. The static & dynamic analysis has been done on computer with the help of STAAD-Pro software using the parameters for the designing as per the IS-1893-2002-Part-1 for the zone (V) and the post processing result obtained has been summarized in succeeding tables.
1st International Conference on Research and Innovation in Civil Engineering (ICRICE 2018), 2018
The demand of high rise building is increasing day by day to accommodate more people in less space. Generally, P-Delta analysis is not performed during design and analysis of Reinforced Concrete framed structure. High rise structure may collapse under severe perimeters if 'P-Delta' analysis is not considered in the analysis and design phase. Due to defective construction practices and ignorance for earthquake resistant design of buildings in our country, most of the existing buildings are vulnerable to future earthquakes. This study deals with the analysis of RC framed regular and irregular buildings in Zone-IIΙ using inelastic method (P-Delta Analysis). The objective of this study is to find out the effect on response quantities (Story Drift, Displacement & Stiffness) due to 'P-Delta' effect on the RC framed structure and also find out the effect of asymmetry on this analysis. 'P-Delta' analysis is nonlinear static analysis, so the structural responses are included the additional response produced due to the simultaneously action of lateral and gravity load on un-deformed as well as deformed geometry. After analysis, it is found that the response quantities are higher if 'P-Delta' effect is considered and in the case of irregular structure the response quantities are higher in compare to the regular structure.
In present scenario, constructing multi-storied buildings such as regular type of buildings are gradually increasing, because due to the cost of site, foundation and architectural aesthetic view. These types of buildings are extremely dangerous if the buildings are built in seismically active regions. When the structures are exposed to critical loads the behavior of the structure is a difficult phenomenon, and is generally dependent on the kind of forces acting on the structure, magnitude of force, and direction on which it is acting. The design of these regular buildings should be proper, otherwise it leads to abrupt damage of the structures, and hence special consideration in analysis is to be given. The P-Delta effect is defined as an extra action by the loads in the structure, because of the structural deformation. In this paper, the effect of P-Delta on multi storey building is studied by using linear static analysis and P-Delta analysis in ETABS v15.2.2. The results obtained from the analysis are compared for Shear force, bending moment and displacement .P-Delta analysis shows 22% more than the Linear Static Analysis .Therefore the effect of P-Delta is important and it should be included in the analysis of multi storey buildings.
Study of P-Delta Effect on Tall Steel Structure
The high rise buildings require high frame structure stability for safety and design purposes. This research focused on Pdelta effect on the Tall Steel Structures and compared with linear static analysis. In this study, a 40 storey steel frame structure with m has been modelled by using SAP2000 structural analysis software with the consideration of P-delta effect. At the same time the influence of different bracing patterns has been investigated. For this reason five types of bracing systems including X, V, Single Diagonal, Inverted V , with unbraced model of same configuration are modelled and analysed. The framed structure is analysed for Earthquake load . After analysis, results showed that displacement due to P-Delta effect is 40% more compared to linear analysis and increase in the Axial force is about 8% for bare frame. The X bracing proved to be more stiff and effective with respect to linear analysis and P-Delta analysis. The decrease in the displacement is about 47.5% and 47.9% for linear and second order analysis.
SEISMIC ANALYSIS USING STAAD Pro FOR L-SHAPED RCC FRAMED BUILDING
IRJET, 2022
In this paper P-delta analysis of building structures is performed, the methods reviewed include the amplification factor method, the direct method, the iterative method, the negative property member method, and the second-order computer program method. The influence of asymmetry of building on the P-delta effect in elastic ranges of behaviour is evaluated. The result indicated that the effect of the P-delta is quite sensitive to characteristics of ground motion such as the frequency content of earthquakes. Under the P-Delta effect, displacement varies exponentially with an increase in height or increment in stories. The axial forces also vary with the height of the structure. Because of the wide variation in displacement with an increase in slenderness, P-Delta analysis is required for structures taller than 7 stories. the P-Delta effect will be substantial when lateral forces exist on the structure and this increases with an increase in the number of stories. The P-Delta effect is not predominant in buildings up to seven stories and it is very negligible when only gravity loading exists on the structure.
ANALYSIS OF A STEEL BUILDING AGAINST EARTHQUAKE LOADS
In the world the most widely used material for building construction is Steel. Steel is playing an important role as a building material with combination of concrete as Reinforced cement concrete in the modern days. With the invention of steel as a building material revolution in high rise construction has been started. The genetic properties of steel like strength, toughness, ductility and other appropriate properties made the engineers to select as a building material and also made the characteristics that are useful for seisimic design. As a designer engineer he should know the application of the steel design rules which is given in code books for the seismic applications. The seismic design of building frame in this paper is based on IS 1893-2002 and codal provisions are considered for the design is IS 800-2007 and STAAD Pro is used for analysis. The present work aims to analyze and design of a multi-bay and multi storied(G+5) steel structure for earthquake forces following IS 1893-2002 and design as per IS 800-2007.The selection of arbitrary sections have been done following a standard procedure and corrections are done accordingly for earthquake loads. The two methods that have been used for analysis are Equivalent static load method and Response Spectrum method. The frame has also been further checked for P-∆ analysis and required corrections has been done and final results are documented. Finally, the design of connection of an interior joint and an exterior joint of the frame have been done and the calculations have been shown and figures are drawn. The cost efficiency of both the methods have been compared.
During analysis of a building structure, normally after complete modeling full loads are applied on entire building frame and linear static analysis is done. But in actual practice the dead load due to each structural element is applied in various construction stages of each story of the building structure due to the material non-linearity behaviour. The loads considered in linear static analysis change in transitory situation and hence the outcomes will not be suitable and satisfactory. Therefore the building structure should be analyzed at every stage of construction taking into account the load variations. Finite element modeling enhances the precision of finite element prototype which takes into account the effects of construction sequence. Here, in this study the effects of linear static analysis, time dependent and construction sequential analysis for two construction materials RCC and steel are compared. Three dimensional modeling for 30 storey building of concrete and steel is done and the analysis results are taken for the same. Both RCC and steel structures have rigid frames. For the seismic analysis zone factor for zone IV and hard soil type is considered according to IS: 1893 (part1)-2002. Therefore the analysis result helps to comprehend the structural responses against load variations for linear static analysis, time dependent and sequential analysis. Finally, a relative study of shear forces, bending moments and displacements was done at every story for conventional model and construction sequence model for two construction materials RCC and steel respectively using the finite element analysis software “ETABS version 13”.