Base Isolation Compared To Capacity Design For Large Corner Periods And Pulse-Type Seismic Records

2021 ◽  
Author(s):  
Dietlinde Köber ◽  
Paul Semrau ◽  
Felix Weber
Keyword(s):  
Base Isolation ◽  
Design Method ◽  
Response Spectrum ◽  
Soil Conditions ◽  
Base Shear ◽  
Capacity Design ◽  
Ground Acceleration ◽  
Seismic Records ◽  
Pulse Type ◽  
Seismic Area

Abstract Southern Romania experiences special soil conditions, leading to rather long corner periods and to an enlarged plateau of the response spectrum, with associated large displacement demands. Pulse-type ground acceleration records complete this unique seismic area. Research on the seismic behavior of structures built under these special conditions is limited and engineers are not comfortable with alternative solutions such as base isolation. This study investigates the seismic performance of a hospital building with the following two anti-seismic solutions: 1) stiffening, in line with the capacity design method and 2) base isolation. Base shear, structural drift and structural acceleration are compared for both approaches.

Combined seismic base shear and torsional loading provisions in the 1990 edition of the National Building Code of Canada

1991 ◽  
Vol 18 (6) ◽  
pp. 945-953
Author(s):  
A. M. Chandler
Keyword(s):  
Ground Motions ◽  
Building Code ◽  
Soil Conditions ◽  
Building Structures ◽  
Base Shear ◽  
Ground Acceleration ◽  
Period Range ◽  
Natural Period ◽  
Short Period ◽  
Edge Response

This paper evaluates the earthquake-resistant design provisions of the 1990 edition of the National Building Code of Canada (NBCC 1990) for asymmetric building structures subjected to combined lateral shear and torsional dynamic loadings arising from earthquake base excitation. A detailed parametric study is presented, evaluating the dynamic edge displacement response in the elastic range, for the side of the building which is adversely affected by lateral–torsional coupling. A series of buildings is studied, with realistic ranges of the fundamental natural period, structural eccentricity, and uncoupled frequency ratio. These buildings are evaluated under base loadings arising from a total of 45 strong motion records taken from earthquakes in North America, Mexico, Europe, the Middle East, and Southern Pacific, categorized according to site soil conditions and the ratio a/v of peak ground acceleration to velocity. The latter parameter together with the uncoupled lateral period are found to influence strongly the combined dynamic edge response, with the greatest forces on edge members arising from earthquakes with high a/v ratio in structures with natural periods below 0.8 s. In this case the NBCC 1990 loading provisions significantly underestimate the elastic dynamic response. For buildings with periods longer than 0.8 s, the conservatism of the base shear provisions leads to overestimation of combined dynamic edge response in asymmetric systems, and this is also true in the short-period range for buildings subjected to ground motions with low a/v ratio. The NBCC 1990 provisions are reasonably conservative for short-period systems subjected to ground motions with intermediate a/v ratio. Key words: earthquakes, seismic, design, response, spectra, base, shear, torsional, provisions.

scholarly journals Seismic and Time History Performance of RCC Framed Buildings with and without Passive Energy Dissipators

2020 ◽  
Vol 9 (3) ◽  
pp. 2230-2240
Keyword(s):  
Base Isolation ◽  
Lateral Displacement ◽  
Response Spectrum ◽  
Time History ◽  
Base Shear ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Seismic Force ◽  
Energy Dissipators ◽  
Lateral Displacements

Base isolation is an effective way to protect large structures from earthquake damage. It is a costly approach, as the entire structure must be supported on elastomeric or sliding bearings. Viscous dampers distributed throughout an otherwise conventional structure can achieve the same result at a significantly lower cost. Dampers are used to resist lateral forces coming on the structure. Dampers are the energy dissipating devices which also resist displacement of Reinforced Concrete (RC) buildings during an earthquake. These dampers help the structure to reduce buckling of columns thereby increasing the stiffness of the structure. During earthquakes, multi-storeyed buildings get damaged and as a result, large deformation occurs. Dampers reduce vibration and deformation of structural elements during an earthquake. Retrofitting buildings with fluid viscous dampers (FVDs) can improve Interstorey drifts and floor accelerations. In the present study, an RC framed building is modelled and analysed under Southern Sumatra and Chile earthquakes to evaluate the performance of the structure and its elements with and without energy dissipators. For the study, a model (G+19) with and without energy dissipators is modelled in ETABS. The seismic force is applied based on the time history data of the models pertaining to Southern Sumatra and Chile Earthquake. Response Spectrum analysis has been carried out to find the lateral displacements, storey shear and Base shear for the model with and without dampers. The lateral displacement, storey drift, storey shear and Base shear are found to less for the model with Linear FVDs when compared to the model with Non-Linear FVDs and without FVDs.

scholarly journals Performance of Six- and Ten-story Reinforced Concrete Buildings Designed by using Modified Partial Capacity Design (M-PCD) Method with 70% Shear Force Ratio

2021 ◽  
Vol 23 (2) ◽  
pp. 131-137
Author(s):  
Pamuda Pudjisuryadi ◽  
F. Wijaya ◽  
R. Tanuwijaya ◽  
B.C. Prasetyo ◽  
Benjamin Lumantarna
Keyword(s):  
Reinforced Concrete ◽  
Shear Force ◽  
Design Method ◽  
Base Shear ◽  
Reinforced Concrete Buildings ◽  
Capacity Design ◽  
Concrete Buildings ◽  
Force Ratio ◽  
Total Base ◽  
Nonlinear Static Procedure

One design alternative of earthquake resistant building is Partial Capacity Design (PCD) method. Unlike the commonly used capacity design method, PCD allows a safe failure mechanism which is called partial sidesway mechanism. In this mechanism, all beams and some columns are allowed to experience plastic damages while some selected columns are designed to remain elastic (called elastic columns). A new approach to predict the required strengths needed to design each structural member, called modified-PCD (M-PCD) is proposed. In this research six- and ten-story reinforced concrete buildings were designed using M-PCD, and their seismic performances are investigated. The base shear force resisted by the elastic columns was set to approximately 70% of the total base shear. Both nonlinear static procedure (NSP) and nonlinear dynamic procedure (NDP) are used to analyze the structures. The results show that the expected partial side sway mechanism is observed, and the drifts of the buildings are acceptable.

scholarly journals Improvement of the Performance-Based Seismic Design Method of Cable Supported Bridges with the Resilient-Friction Base Isolation Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 3942 ◽  
Author(s):  
Heungbae Gil ◽  
Kyoungbong Han ◽  
Junho Gong ◽  
Dooyong Cho
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Modal Shape ◽  
Ground Acceleration ◽  
Performance Based Seismic Design ◽  
Seismic Design Method ◽  
Shape Analyses

In areas of civil engineering, the resilient friction base isolator (R-FBI) system has been used due to its enhanced isolation performance under seismic excitations. However, because nonlinear behavior of the R-FBI should be reflected in seismic design, effective stiffness (Keff) of the R-FBI is uniformly applied at both peak ground acceleration (PGA) of 0.08 g and 0.154 g which use a multimodal response spectrum (RS) method analysis. For rational seismic design of bridges, it should be required to evaluate the dynamics of the R-FBI from in-field tests and to improve the seismic design procedure based on the performance level of the bridges. The objective of this study is to evaluate the dynamics of the R-FBI and to suggest the performance-based seismic design method for cable-supported bridges with the R-FBI. From the comparison between the experiments’ results and modal shape analyses, the modal shape analyses using primary (Ku) or infinite stiffness (fixed end) showed a great agreement with the experimental results compared to the application of Keff in the shape analysis. Additionally, the RS or nonlinear time history method analyses by the PGA levels should be applied by reflecting the dynamic characteristics of the R-FBI for the reasonable and efficient seismic design.

Comparison between fixed base and isolated base in seismic response of high-rise buildings: a case study

2020 ◽  
Vol 6 (4) ◽  
pp. 204
Author(s):  
Anas M. Fares
Keyword(s):  
Response Spectrum ◽  
Soft Soil ◽  
Structural Response ◽  
Time History ◽  
Soil Condition ◽  
Soil Conditions ◽  
Spectral Acceleration ◽  
Base Shear ◽  
High Rise ◽  
Fixed Base

In this study, the influence of soil condition under the isolated and fixed bases is studied by using ETABS 16 software for the high-rise regular building. A regular building with 10 floors is modeled and the results are obtained for story displacements, story shear forces and spectral acceleration according to Uniform Building Code 97 (UBC-97) code. The time history analysis has been performed by using 1999 Izmit earthquake record. 3 types of soil which had different stiffnesses are considered in this study. The results show that the value of base shear increases when the soil stiffness decreases. It also noticed that the spectral acceleration is larger in soft soil condition than that of other soil conditions; and this confirms that the structural response spectrum is associated with the soil condition. In addition, when using base isolated building the drift of lower floors will be larger than that of using base isolated, but in the upper floors the drifts of fixed base building will be larger than that of the isolated base building. Finally, time history method in the seismic design will produce base shear less than that from equivalent static method, so calibration factor for design purpose shall be used.

Evaluation of Liquefaction Potential of Soil at a Power Plant Site in Chittagong, Bangladesh

2020 ◽  
Vol 11 (1) ◽  
pp. 1-16
Author(s):  
Soumyadeep Sengupta ◽  
Sreevalsa Kolathayar
Keyword(s):  
Power Plant ◽  
Response Spectrum ◽  
Ground Level ◽  
Standard Penetration Test ◽  
Combined Cycle ◽  
Point Of View ◽  
Soil Conditions ◽  
Ground Acceleration ◽  
Liquefaction Potential ◽  
Plant Site

This study presents an evaluation of liquefaction potential for combined cycle power plant site located in the Chittagong district, Bangladesh, using standard penetration test blow counts (SPT-N values). The peak ground acceleration (PGA) values at a bedrock level were estimated deterministically using both linear and point source models as well as different ground motion prediction equations (GMPEs). The surface level hazard was estimated using amplification factors for the soil conditions present and the response spectrum at the center of the plant site was plotted. The liquefaction potential for the site was arrived at by using the SPT-N values of 33 boreholes in the site and at every 3-meter interval from the ground level to a depth of 30 meters. The results from the LPI contours at successive depths indicate that in the majority of the borehole locations, the soil up to 15 meters depth had a significant hazard of liquefaction. These findings from the present study can prove to be crucial from the structural point of view, for any future construction activities in the area.

scholarly journals The Structural Performance Analysis of Base-Isolated Hospital Buildings with Analysis Modal (Case Study: General Hospital in Labuhan Batu Utara Regency Area)

2019 ◽  
Vol 1 (2) ◽  
pp. 63-78
Author(s):  
Muhammad Irwansyah ◽  
Johannes Tarigan ◽  
Zulfazly Putra
Keyword(s):  
General Hospital ◽  
Base Isolation ◽  
Response Spectrum ◽  
Significant Risk ◽  
Structural Performance ◽  
Building Structures ◽  
Base Shear ◽  
Earthquake Force ◽  
Isolated Structures ◽  
Base Isolators

The development of earthquake analysis towards structures is required to prevent damages and loss in buildings due to earthquakes. The base isolation system is a simple design approach for earthquake-resistant buildings to protect the structures and components from the risk of earthquake damages by using the concept of reducing earthquake forces. This research aims to analyze the performance of a general hospital building in Labura Regency area in order to know the safety of the building in terms of period, frequency, base shear force, displacement and earthquake force, used the base isolators and without the base isolators. The method used is response-spectrum dynamic analysis by ETABS v2016 program. From the calculation of structural analysis, the application of base isolation is able to build up the period of the structure, therefore, the maximum acceleration of earthquakes can be reduced at certain period. There is an average increase by 48.21% of the structural period compared to non-isolated base structure, and the frequency that occurs in structures using base isolators is smaller than without base isolators. The friction force obtained is smaller compared to the structures without dampers. Base-isolated building structures observed have bigger displacement than non-base isolated structures. The average rise of the building displacement is 27.14% at x and 2.74% at y directions. In base-isolated structures, earthquake forces are reduced averagely by 57.51% at x and 82.73% at y directions. The analysis of structural performance, General Hospital in Labura Regency is categorized to Immediate Occupancy (IO) in which the building structures are safe with no significant risk of fatalities due to structural failures, there are no any significant damages and the building can be used and functioned/operated again immediately.

Research of Soil Layers Amplification Effect Based on Strong Seismic Records and Calculations

2014 ◽  
Vol 580-583 ◽  
pp. 1604-1608
Author(s):  
Liang Wang ◽  
Ya Su
Keyword(s):  
Seismic Response ◽  
Response Spectrum ◽  
Soil Conditions ◽  
Predominant Period ◽  
Soil Layers ◽  
Amplification Effect ◽  
Comparison Research ◽  
Program Calculation ◽  
Calculation Results ◽  
Seismic Records

This paper states the comparison research of calculation results from program LSSRLI-1 and program SHAKE2000, with the strong seismic records as well as the site soil conditions by using borehole arrays. The analytical results show that the site soil conditions have an amplification effect on the seismic PGA and response spectrum values, however, the actual seismic records are not consistent with the program calculations on the amplification effect. Besides, the site soil conditions also have an altering effect on the predominant period of seismic response spectrum, where actual seismic records and program calculation results of the altering effect are not the same either.

A Direct Displacement-Based Design Method Based on Chinese Code of Base Isolated Structures

2011 ◽  
Vol 255-260 ◽  
pp. 2555-2559
Author(s):  
Zhen Sun ◽  
Wei Qing Liu ◽  
Shu Guang Wang ◽  
Ding Zhou ◽  
Dong Sheng Du
Keyword(s):  
Seismic Isolation ◽  
Design Method ◽  
Response Spectrum ◽  
Base Shear ◽  
Direct Displacement Based Design ◽  
High Intensity Zone ◽  
Lead Rubber Bearings ◽  
Displacement Based ◽  
Rubber Bearings ◽  
Relationship Of

A simple and efficient direct displacement-based design (DDBD) method is introduced to base isolated (BI) structures. Assuming the vibration mode of superstructure to be the shear type and considering the BI structure to be an equivalent single degree of freedom (ESDOF) system with spring and damper at the seismic isolation layer. The acceleration response spectrum in Chinese code is converted to displacement response spectrum. Corresponding to the design displacement, the equivalent period is obtained. The relationship of the deign displacement, equivalent period, equivalent stiffness and base shear of the system can be derived from the given formulations. Then, the distribution of the base shear along the floors is obtained. This method has been applied to the design of a 12-story BI structure with lead rubber bearings in high intensity zone in Suqian city, Jiangsu province. The results show that the method is feasible for the design of BI structures.

scholarly journals Alternative approach in Partial Capacity Design (PCD) by using predicted post-elastic story shear distribution

2021 ◽  
Vol 907 (1) ◽  
pp. 012007
Author(s):  
H Herryanto ◽  
L S Tanaya ◽  
P Pudjisuryadi
Keyword(s):  
Design Method ◽  
Response Spectrum ◽  
Seismic Load ◽  
Capacity Design ◽  
Plastic Hinges ◽  
Design Response Spectrum ◽  
Non Linear ◽  
Earthquake Resistant Structures ◽  
The One ◽  
Design Earthquake

Abstract The Capacity Design Method is an approach widely used to design earthquake resistant structures. It allows the structures to dissipate earthquake energy by forming plastic hinges through beam side sway mechanism. In the design process, the columns need to be designed stronger than the beams connected to them. Several previous studies have been conducted to propose alternative method allowing partial side sway mechanism namely the Partial Capacity Design (PCD) Method. In this method, selected columns are designed to remain elastic and the plastic hinges are allowed to occur only at the columns base. These columns are designed to resist increased forces. Despite of some successful attempts, PCD method still needs to be developed because sometimes the intended mechanism was not observed. This study proposes a new approach to improve the Partial Capacity Design (PCD) method. Symmetrical 6 and 10 story buildings with 7 bays are analyzed using seismic load for city of Surabaya. Structure behavior under non-linear static analysis is well predicted by this approach. However, under non-linear dynamic analysis, a few unexpected plastic hinges of elastic columns were observed at upper stories. But it should be noted that the earthquake used for performance analysis (maximum considered earthquake) is 50% larger than the one used for design (earthquake level corresponding to elastic design response spectrum).

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