scholarly journals Effect of Steel Bracings on RC Building by Aligning Them at Different Positions

2019 ◽  
Vol 9 (1) ◽  
pp. 2429-2432
Keyword(s):  
Structural Steel ◽  
Pushover Analysis ◽  
Vertical Direction ◽  
Tall Buildings ◽  
Lateral Load ◽  
Braced Frame ◽  
Time Period ◽  
Non Linear ◽  
Story Drift ◽  
Rc Building

Earthquake is an unexpected and expensive disaster for both livelihood and economy. In the modern day construction there has been a lot of importance to make the structure resistive against the laterally acting loads. Bracings are an option for lateral load resisting system in tall buildings. The concept of bracings is to add more stiffness and strength to the adequate strength of the structure. Members in a braced frame are generally made of structural steel which can work effectively both in strain and pressure. In the present work 13 story irregular building is considered with and without bracings to evaluate the optimum bracing pattern for the structure. By changing the position of the bracings alternately in both horizontal and vertical direction the analysis is carried out. These are the different models analyzed by pushover analysis (a) Building with no bracing, (b) Building with alternate vertical bracing starting from bay-1, (c) Building with alternate vertical bracing starting from bay-2, (d) Building with alternate vertical bracing starting from story-1, (e) Building with alternate vertical bracing starting from story-1. The non linear static results were compared. The various parameters like story drift, shear, time period, stiffness, moment, torsion, performance points are obtained by the analysis for all the models.

Pushover Analysis of Base Isolated RC Frame Buildings With Masonry Infills

2019 ◽  
Vol 10 (2) ◽  
pp. 18-31
Author(s):  
Radhikesh Prasad Nanda ◽  
Subhrasmita Majumder
Keyword(s):  
Base Isolation ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Base Shear ◽  
Infilled Frame ◽  
Masonry Infills ◽  
Time Period ◽  
Frame Buildings ◽  
Story Drift ◽  
Rc Frame Buildings

In the present article, the performance of base-isolated infilled frames is studied analytically. The seismic performances of four RC buildings, namely RC bare frame without isolator, RC bare frame with isolator, RC infilled frame without isolator, and RC infilled frame with isolator are analysed. The results show a decrease in base shear value and increase in time period due to base isolated buildings, while these parameters are reversely affected due to infills. The decrease in story drift for the base isolated buildings is in phase while considering infill. Also, it can be inferred that plastic hinge formation is greatly affected by the introduction of masonry infill. Hence, relying on base isolation without considering infills may underestimate the seismic performance.

scholarly journals Study of Seismic Response Demands of Different L-shaped Buildings

2020 ◽  
Vol 1 (1) ◽  
pp. 23-29
Author(s):  
Bharat Khanal ◽  
Hemchandra Chaulagain
Keyword(s):  
Seismic Response ◽  
Response Spectrum ◽  
Lateral Force ◽  
Mode Shapes ◽  
Building Frames ◽  
Time Period ◽  
Standard Code ◽  
Story Drift ◽  
Rc Building ◽  
Element Approach

The present study evaluates the effect of plan configuration irregularity of different L shaped models. For this, one regular and six different L-shaped RC building frames were modeled for numerical analysis. The analysis was done through an equivalent static lateral force method and response spectrum analysis (dynamic analysis). The seismic response demands were measured in terms of story displacement, inter-story drift ratio, torsional irregularity ratio, and torsional diaphragm rotation. In addition, fundamental time period of structure, vibration mode shapes and modal participating mass ratios were also studied. The study shows that the fundamental time period of structure based on standard code shows a lower value as compared to a finite element approach. It is concluded that to account for the irregularities present within the buildings, current code provisions are insufficient and should be amended.

scholarly journals Analog Search of Different Lateral Load Resisting System for High Rise Building

2019 ◽  
Vol 8 (2S3) ◽  
pp. 476-480
Keyword(s):  
Tall Buildings ◽  
Lateral Load ◽  
Exterior Surface ◽  
High Rise ◽  
Column System ◽  
Time Period ◽  
Exhaustive Study ◽  
Strength And Stiffness ◽  
Diagrid Structure ◽  
Seismic Forces

As the rate of growth of population is increasing day by day, the requirement of land is increasing for different purposes. To accommodate this increased population, the height of building is increasing thereby subsequently increasing the importance of lateral load resisting system which provide adequate strength against lateral loading arising due to earthquake and wind. In present study various lateral load resisting system have been introduced which can resist the lateral forces and safely transfer them to soil thereby improving the strength and stiffness of column structures. The lateral load resisting systems that are widely used are conventional beam column system, shear wall system, tube system, outrigger system, tubular system etc. Diagrid structural system is generally adopted in tall buildings due to its structural efficiency and flexibility in planning. Compared to closely space vertical columns in Conventional Beam column system, diagrid structure consists of inclined columns on the exterior surface of building. The concrete diagrids member is used in both precast and cast in-situ type. An exhaustive study has been performed on the performance of 20 storey RCC building with plan size 18 m × 18 m using E-TAB software. All structural members are designed as per IS 456:2000 and all the load combinations of seismic forces are considered as per IS 1893(Part 1): 2002. Finally, Parameter such as storey displacement, storey stiffness and time period are compared and obtained results were presented in both graphically and tabular format

Seismic Performance Evolution of Tube-in-Tube Diagrid Structure Using Non Linear Static Analysis

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
M. K. Laghate ◽  
M. K. Laghate
Keyword(s):  
Static Analysis ◽  
Seismic Performance ◽  
Lateral Displacement ◽  
Pushover Analysis ◽  
Lateral Load ◽  
High Rise ◽  
Load Carrying ◽  
Non Linear ◽  
Diagrid Structure ◽  
Linear Static Analysis

Diagrid structures are evolved as one of the best structural system for high rise buildings. In this study seismic performance of 36 stories Tube-in-Tube Diagrid Structure with various diagonal slopes is evaluated by Non Linear Static Analysis. Tube-in-Tube diagrid structures are modified Diagrid structures in which gravity core is replaced with Diagrid core. Single tube diagrid structure is also studied for comparison. The structure is pushed gradually proportional to fundamental Mode shape. The analysis results shows that Tube-in-Tube structure possess higher stiffness and Lateral Load resisting capacity. The pushover analysis demonstrates that diagrid core can perform better by hardening the structure. According to analysis results, the Tube-in-Tube diagrid structure shows higher non-linear lateral displacement. It was observed that as the diagrid angle increases the stiffness and lateral load carrying strength decreases.

Analysis of Multi-Story Buildings with Hybrid Shear Wall - Steel Bracing Structural System

2021 ◽  
Author(s):  
Shubam Sharma ◽  
Aditya Kumar Tiwary
Keyword(s):  
Finite Element ◽  
Shear Walls ◽  
Steel Structures ◽  
Lateral Load ◽  
Structural System ◽  
Base Shear ◽  
Time Period ◽  
Story Drift ◽  
Overturning Moment ◽  
Comparative Results

Abstract Numerous studies were contemplated on the structures with distinctive structural configuration and ample amount of work is currently being performed through the investigation of the response of individual behavior of shear walls and bracings by varying configurations and their material properties. Seismic design philosophies had mentioned firmly that a structure must accomplish Life Safety (LS) and Performance Level (PL) for both reinforced concrete and steel structures. This study is anchored on prevailing lateral load resisting system which is virtuous but not adequate to retain vigorous ground motion or acceleration. To overwhelm this problem, an attempt was made to familiarize a new lateral load resisting system formulated by the amalgamation of two different existing lateral load resisting systems, specifically shear walls and bracings. The hybrid structural system embraces two distinctive lateral load resisting techniques, shear walls, and bracings for moment-resisting frame. A numerical finite element study was carried out by the linear dynamic method on the response of structure subjected to seismic condition and an optimal configuration of the different structural patterns is assured by using numerous possible patterns of a hybrid structural system using finite element-based software. The criteria contemplated for study including time period, base shear, overturning moment, story drift ratio, and story displacement are compared with different models and the optimal structure is concluded based upon the recital. The comparative results revealed that there is a reduction noticed in the fundamental time period, and story displacement, where as there is negligible increment in base shear and overturning moment for the hybrid structural system as compared to other configurated models.

On a Process of Rapid Estimation of Seismic Demands for Generic Steel Frame Structures

2005 ◽  
Author(s):  
Chiung-Yueh Lin ◽  
Wei-Zhi Chen ◽  
Tysh-Shang Jan
Keyword(s):  
Pushover Analysis ◽  
Tall Buildings ◽  
Frame Structures ◽  
Seismic Demands ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
History Analysis ◽  
Story Drift ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

The seismic demands of tall buildings can be evaluated by nonlinear response history analysis with some more representative, site-dependent, earthquakes, or by pushover analysis. However, the process of the evaluation is tedious and time consuming. Therefore, it is desirable to have a simplified process that provides quick and reasonable estimates of seismic demands, especially in the stage of conceptual (preliminary) design. Gupta & Krawinkler (2000) has reached on a process in the estimation of roof and story drift demands for frame structures from the spectral displacement at the first period of the structure, through a series of modification factors, accounting for MDOF effects, inelasticity effects, and P-delta effects. It is found that this process can estimate seismic demands reasonably, provided that no negative post-yield story stiffness exists. Also, the modification factors are uniform or with reasonable dispersion, except for structures dominated by higher mode effects. This study has conducted a similar research by performing simulations on Taiwan code–compliant structures of different heights (2,5,10,20 and 30 stories), located in different seismic zones and subjected to sets of local ground motions. The feature of this study is that the seismic demands are estimated from the SRSS of the elastic, modal roof displacements of the structure, instead of the first mode spectral displacement. The simulation results have shown that the modification factors are more promising — uniform or with more reasonable dispersion — even the structure is dominated by high mode effects. Therefore, it is concluded that the process proposed in this study is a feasible method and the modification factors obtained in this study are useful for local engineer in engineering applications.

scholarly journals The Effect of Shear Wall Configuration on Seismic Performance in the Hotel Building

2018 ◽  
Vol 159 ◽  
pp. 02074
Author(s):  
Daud Rahmat Wiyono ◽  
Roi Milyardi ◽  
Cindrawaty Lesmana
Keyword(s):  
Seismic Performance ◽  
Structural Damage ◽  
Shear Wall ◽  
Lateral Load ◽  
Dual System ◽  
Frame Structure ◽  
Seismic Load ◽  
Time Period ◽  
Story Drift ◽  
Slender Columns

Earthquake effects on the buildings must be evaluated within the current standard provision. The shape of building gives a unique seismic performance on the structure. In typical hotel building, the lobby area in the first floor usually has some slender columns due to the needs of higher clearance to give a widely space area. The slender columns in the big hall tends to create asymmetric building and torsional behaviour on seismic performance. This behaviour is one of the most frequent source of structural damage and failure. One of the solution is to add shear wall in elevator area. The purpose of this paper is to seek the effect of shear wall configuration in elevator area on the seismic performance through numerical analysis. There are some requirements for structural analysis under seismic load, such as: time period, modal analysis, story drift, and other details. In building with dual system, story shear in frame at each level must carry over 25 % of total story shear at that level. In this study, an eleven-storey hotel building located in Tanjung Pinang City, Indonesia was evaluated due to gravity and seismic load. For the building, the requirements of the time period from the standard are 1.21 sec (minimum) and 1.70 sec (maximum). As results, two-sided shear wall in X direction and two-sided shear wall in Y direction is recommended because it has the best seismic performance, time period below the minimum, story drift below allowable, the dynamic lateral load has meet minimum requirement (85% Static Load), and frame structure has carry more than 25% lateral load in dual system building.

scholarly journals Performannce Base Analysis of Multy Storied Building

2021 ◽  
Vol 9 (8) ◽  
pp. 2053-2062
Author(s):  
Kunwer Fahmed Alam Ariyana
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Horizontal Load ◽  
Base Shear ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Linear Approach ◽  
Time Period ◽  
Non Linear ◽  
Pushover Curve

Abstract: In India multistoried buildings are widely designed with the method suggested by Indian Standard IS1893: Part-1:2016, Criteria for the Earthquake resistance design of the structures: General Provision and Buildings for the calculation of equivalent horizontal load generated during earthquake. Response Spectrum method is widely used for the multistoried buildings with base shear scaled to get the equal value as calculated with the time period obtained by the empirical formula of time period of the buildings. The approach of the dynamic analysis is basically a linear approach. In this scenario we are totally relying on ductility of the structure. The concept for performing the Pushover Analysis is to analyze a structure with non linear approach and to find the behavior of structure beyond its ductile limit. Pushover analysis can help to demonstrate how progressive failure in building really occurs and to identify the mode of final failure of the buildings. Pushover analysis is commonly used to evaluate the seismic capacity of existing structures and appears in several recent guidelines for retrofit seismic design. It can also be useful for performance-based design of new buildings that rely on ductility or redundancies to resist earthquake forces. So basically Pushover analysis is non linear approach to estimate the strength capacity of the structure beyond Limit State. In this analysis we can predicts the weak areas in the building and keeping track of the sequence of damages of each and every member in the building/structure, thus can be performed for existing structure and also for performance base design, similarly for progressive collapse analysis. The approach is easy to understand, when we designed or analyze a moment resisting frame as per IS 1893:2016 by Response Spectrum method with response spectrum method with the response reduction factor 5 i.e. R=5, we are basically designing the structure with 1/5th horizontal load (calculated with the empirical formula given in IS 1893:2016), the rest 4/5th load is basically taken care by the ductile behavior of the building. The ductile detailing suggested by the 13920:2016 will resist the full impact of seismic load without collapse. The distribution and impact of the full horizontal load can be analyzed with the non linear approach, and pushover analysis is one of them. METHODLOGY: A pushover analysis is performed by subjecting a structure to a monotonically increasing pattern of lateral loads, representing the inertial forces which would be experienced by the structure when subjected to ground shaking. Under incrementally increasing loads various structural elements may yield sequentially. Consequently, at each event, the structure experiences a loss in stiffness. Using a pushover analysis, a characteristic non linear force displacement relationship can be determined. Key elements of the pushover analysis 1) Definition of plastic hinges, it includes hinges for uncoupled moment, hinges for uncoupled axial load, hinges for uncoupled shear force, hinges for coupled axial force and hinges for biaxial bending moment. 2) Definition for control node, the node used to monitor the displacement of the structures. Pushover curve is obtained from the displacement verses base shear. 3) Developing the pushover curve which includes the elevation of the forces distribution 4) Estimation of the displacement demand. 5) Evaluation of performance level for the structure

scholarly journals Bracing Applications for Improving the Earthquake Performance of Reinforced Concrete Structures

2020 ◽  
Vol 9 (3) ◽  
pp. 2179-2182
Keyword(s):  
Reinforced Concrete ◽  
Pushover Analysis ◽  
Concrete Structures ◽  
Shear Walls ◽  
Lateral Load ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Base Shear ◽  
Braced Frame ◽  
Rc Frames

Braced frames, besides other structural systems, such as shear walls or moment resisting frames, have been a valuable and effective technique to increase structures performance against seismic loads. In wind or seismic excitations, diagonal members react as truss web elements which would afford tension or compression stresses. This study purposes at considering the effect of bracing diagonals on values of base shear and displacement of building. Two models were created and nonlinear pushover analysis has been implemented. Results show that bracing members enhance the lateral load performance of RC frames considerably. The purpose of this article is to study the nonlinear response of reinforced concrete Structures which contain Hollow Pipe Steel braces as the major structural elements versus earthquake loads. A five-storey reinforced concrete structure was selected in this study; two different reinforced concrete frames were considered. The first system was un-braced frame while the last one was braced frame with diagonal bracing. Analytical modelings of the bare frame and braced frame were realized by means of SAP 2000. The performances of all structures were evaluated using the nonlinear static analyses. From these analyses, the base shear and displacements were compared. Results are plotted in diagrams and discussed extensively and the results of the analyses showed that, the braced frame was seemed to capable of more lateral load carrying, had the high value for stiffness and lower roof displacement in comparison with bare frame.

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