scholarly journals Seismic bridge pier analysis for pile foundation by force and displacement based approaches

2015 ◽  
Vol 13 (2) ◽  
pp. 155-166
Author(s):  
NP.R. Singh ◽  
Hemant Vinayak
Keyword(s):  
Pile Foundation ◽  
Seismic Analysis ◽  
Slenderness Ratio ◽  
Soft Soil ◽  
Time History ◽  
Bridge Pier ◽  
Base Shear ◽  
Displacement Based ◽  
Shear Demand ◽  
Analytical Approaches

Seismic analysis of bridge pier supported on pile foundation requires consideration of soil-pile-structure (kinematic and inertial) interactions. This paper presents the design forces generated for bridge piers with varying height and constant diameter for medium and soft soils in earthquake probability zones considering contribution of soil-pile-structure interactions by developed analytical approaches. The results have shown that the difference in base shear demand between force based and displacement based approach and that between capacity spectrum and displacement based method in general decreases with the increase in slenderness ratio of the pier. The base shear demand by non-linear time history analysis has been found to be much higher compared to that by other methods. The relationship between height and pier cross-section has been developed for different soils and seismic zones such that the base shear demands by force based and displacement based method are of the same order. The overall value of the slenderness ratio works out to be such that failure of the pile shall be as a short column for both medium and soft soil.

scholarly journals Assessment of Soil-Structure Interaction in Seismic Bridge Pier Analysis Using Force and Displacement Based Approaches

2015 ◽  
Vol 10 (2) ◽  
pp. 113-126
Author(s):  
R N P Singh ◽  
Hemant Kumar Vinayak
Keyword(s):  
Soil Structure ◽  
Seismic Analysis ◽  
Soft Soil ◽  
Bridge Pier ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Structure Interaction ◽  
Capacity Spectrum ◽  
Fixed Base ◽  
Displacement Based

Abstract The seismic analysis carried out assuming foundation to be perfectly rigid and bonded to the soil underneath is far from truth and therefore, the soil-structure interaction effect on the dynamic behavior of the bridge pier should be considered. The assessment of soil-structure effect on the design force generated has been estimated using Force based, Capacity Spectrum and Direct Displacement based methods considering fixed and flexible foundations. For this purpose a single cantilever bridge pier of constant diameter with varying heights has been considered for the analysis in different type of soils and earthquake zones. The study has revealed that soil-Structure Interaction index is negative in some cases, especially in soft soil, implying base shear demand being greater than that of fixed base contrary to the traditional views.

scholarly journals Implementation of the structural performance factor (Sp) within a displacement-based design framework

2018 ◽  
Vol 51 (3) ◽  
pp. 159-165 ◽  
Author(s):  
Dion Marriott
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Structural Performance ◽  
Integration Time ◽  
Design Framework ◽  
Base Shear ◽  
Structural Behaviour ◽  
Performance Factor ◽  
Design Response Spectrum ◽  
Displacement Based

This paper discusses the application of the Structural Performance factor (SP) within a Direct Displacement-Based Design framework (Direct-DBD). As stated within the New Zealand loadings standard, NZS1170.5:2004 [1], the SP factor is a base shear multiplier (reduction factor) for ductile structures, i.e. as the design ductility increases, the SP factor reduces. The SP factor is intended to acknowledge the better-than-expected structural behaviour of ductile systems (both strength, and ductility capacity) by accounting for attributes of response that designers are unable to reliably estimate. The SP factor also recognizes the less dependable seismic performance of non-ductile structures, by permitting less of a reduction (a larger SP factor) for non-ductile structures. Within a traditional force-based design framework the SP factor can be applied to either the design response spectrum (a seismic hazard/demand multiplier), or as a base shear multiplier at the end of design (structural capacity multiplier) – either of these two approaches will yield an identical design in terms of the required design base shear and computed ULS displacement/drift demands. However, these two approaches yield very different outcomes within a Direct-DBD framework – in particular, if SP is applied to the seismic demand, the design base shear is effectively multiplied by (SP)2 (i.e. a two-fold reduction). This paper presents a “DBD-corrected” SP factor to be applied to the design response spectrum in Direct-DBD in order to achieve the intent of the SP factor as it applies to force-based design. The proposed DBD-corrected SP factor is attractive in that it is identical to the SP relationship applied to the elastic site hazard spectrum C(T) for numerical integration time history method of analysis within NZS 1170.5:2004 [1], SP,DDBD = (1+SP)/2.

scholarly journals Seismic Analysis Method for Underground Structure in Loess Area Based on the Modified Displacement-Based Method

2021 ◽  
Vol 11 (23) ◽  
pp. 11245
Author(s):  
Ruijie Zhang ◽  
Dan Ye ◽  
Jianting Zhou ◽  
Dengzhou Quan
Keyword(s):  
Design Research ◽  
Seismic Analysis ◽  
Design Method ◽  
Underground Structure ◽  
Time History ◽  
Shaking Table ◽  
Underground Structures ◽  
Loess Area ◽  
Geological Conditions ◽  
Displacement Based

At present, the seismic design research of underground structures in loess areas is lagging behind compared with practical engineering requirements. The selection of seismic calculation methods and parameters does not consider the influences of the special geological conditions in various regions, so their usefulness is limited. Based on the above problems, a modified displacement-based method (DBM) was proposed and its application was compared with the most commonly used methods of analysis (force-based design method, displacement-based design method, detailed equivalent static analysis numerical method, and the full dynamic time-history method). The results were also validated by considering data from shaking table tests conducted on a case study involving the underground Feitian Road subway station in Xi’an. The results show that compared with DBM, the average accuracy of the modified DBM technique is improved by 41.65%. The modified DBM offers good accuracy, simplicity in its model, a rapid analysis time, and easy convergence.

scholarly journals Review on Seismic Analysis of Multistoried Building in Hilly Region

2021 ◽  
Vol 9 (12) ◽  
pp. 73-79
Author(s):  
Harsh Joshi
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Center Of Mass ◽  
Time History ◽  
Lateral Loads ◽  
Base Shear ◽  
Building Frames ◽  
Building Frame ◽  
History Analysis ◽  
Hilly Region

Abstract: Due to sloping land and high seismically active zones, designing and construction of multistory buildings in hilly regions is always a challenge for structural engineers. This review paper focuses to establish a review study on the Possible Types of building frame configuration in the hilly region and he behavior of Such building frames under seismic loading conditions, and (3) The recent research and developments to make such frames less vulnerable to earthquakes. This paper concludes that the dynamics characteristics of such buildings are significantly different in both horizontal and vertical directions, resulting in the center of mass and center of stiffness having eccentricity at point of action and not vertically aligned for different floors. When such frames are subjected to lateral loads, due to eccentricity it generates torsion in the frame. Most of the studies agree that the buildings resting on slanting ground have higher displacement and base shear compared to buildings resting on plain ground and the shorter column attracts more forces and undergoes damage when subjected to earthquake. Keywords: Building frame configuration, Seismic behavior, Dynamic characteristics, Response spectrum analysis, time history analysis.

Seismic Analysis and Displacement-Based Evaluation of the Brooklyn-Queens Expressway, New York

2003 ◽  
Vol 1845 (1) ◽  
pp. 213-225
Author(s):  
Robert A. Dameron ◽  
Serafim G. Arzoumanidis ◽  
Steven W. Bennett ◽  
Ayaz Malik
Keyword(s):  
New York ◽  
Reinforced Concrete ◽  
Seismic Analysis ◽  
Nonlinear Models ◽  
Pushover Analysis ◽  
Time History ◽  
Performance Criteria ◽  
Nonlinear Material ◽  
Reinforced Concrete Structure ◽  
Displacement Based

The Brooklyn–Queens Expressway (BQE), Interstate 278 between Atlantic Avenue and Washington Street in Kings County, is an approximately 1,500-m-long multiple-level highway reinforced concrete structure that was built in 1948. It is an important transportation link in the New York City metropolitan area and serves a daily traffic volume of 122,000 vehicles. The longest portion of the BQE consists of elevated one-, two-, and three-level cantilever structures. They are built into the hillside of Brooklyn Heights in successive levels, set back to provide light and air to three lanes of traffic in each direction. They have a unique configuration consisting of rigid frames supporting the roadways with long cantilevers, serving also as retaining walls supporting the hillside beneath adjacent brick buildings. The reinforced concrete portions of the BQE were modeled with finite elements that explicitly represented the concrete and reinforcement and used nonlinear material models. The displacement performance was determined in cyclic pushover analysis that predicted concrete cracking and reinforcing bar yielding. This performance was compared with recently developed displacement performance criteria to establish displacement capacities. The displacement demands were determined by time history analyses using nonlinear models. The methods and criteria that were used for evaluation of the BQE structures are described, and conclusions that may be applicable to future seismic evaluations using the displacement-based approach are provided. Other project challenges are also discussed, including the seismic effects of adjacent buildings and subway tunnels.

scholarly journals Comparative Study on seismic analysis and Retrofitting of an Existing Building

2021 ◽  
Vol 9 (VII) ◽  
pp. 3018-3027
Author(s):  
Muniraju J
Keyword(s):  
Seismic Analysis ◽  
Time History ◽  
Time Frame ◽  
Base Shear ◽  
Existing Building ◽  
Building Model ◽  
Removal Time ◽  
Stacking Condition ◽  
Similar Code ◽  
The Impact

The target of this undertaking is to examine and comprehend the impact of utilizing retrofitting strategies on a structure against the seismic unique burden. The investigation is completed on four models of a G+4 building. Model 1 was not exposed to any seismic burden and was discovered to be protected against the arrangement load and live burden and its blend. Model 2 was exposed to dynamic seismic burden and its mix and the disappointment of primary individuals was noted. Accordingly retrofitting was done in the following two models. In Model 3 the structure was retrofitted with bracings were as in Model 4 section jacketing and in Model 5 shear divider were utilized. Boundaries like removal, time history, firmness and base shear were chosen subsequent to leading a careful writing audit. Time-frame of the structure was ascertain according to IS1893-2016, and Zone factor was chosen as 0.1 and 0.16 alongside significance factor as 1 and Soil type as II from a similar code. Then, at that point the same static examination and reaction range investigation was completed on Models 2,3,4 and 5 individually and there results were arranged. In light of the outcomes acquired for the given boundaries and dynamic stacking condition it was reasoned that retrofitting the structure will in general decrease the impacts of dynamic stacking on the design. Further it was noticed that retrofitting the structure with shear divider gave the best suitable outcomes. As it diminished the time-frame of the structure by 32.72% and furthermore lessen the sidelong relocation and story float in both X and Y heading by a decent edge.

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.

Displacement-based seismic design of regular reinforced concrete shear wall buildings

2011 ◽  
Vol 38 (6) ◽  
pp. 616-626 ◽  
Author(s):  
JagMohan Humar ◽  
Farrokh Fazileh ◽  
Mohammad Ghorbanie-Asl ◽  
Freddy E. Pina
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Pushover Analysis ◽  
Shear Wall ◽  
Base Shear ◽  
Ductility Demand ◽  
Inelastic Demand ◽  
Displacement Based ◽  
Ductility Capacity ◽  
Shear Demand

A displacement based method for the seismic design of reinforced concrete shear wall buildings of regular shape is presented. For preliminary design, approximate estimates of the yield and ultimate displacements are obtained, the former from simple empirical relations, and the latter to keep the ductility demand within ductility capacity and to limit the maximum storey drift to that specified by the codes. For a multi-storey building, the structure is converted to an equivalent single-degree-of-freedom system using an assumed deformation shape that is representative of the first mode. The required base shear strength of the system is determined from the inelastic demand spectrum corresponding to the ductility demand. In subsequent iterations a pushover analysis for the force distribution based on the first mode is used to obtain better estimates of yield and ultimate displacements taking into account stability under P–Δ effect. A multi-mode pushover analysis is carried out to find more accurate estimates of the shear demand.

Displacement-based determination of BRBs in retrofitting an RC frame building

2021 ◽  
pp. 136943322098166
Author(s):  
Yumei Wang
Keyword(s):  
Time History ◽  
Mode Shapes ◽  
Rc Frame ◽  
Two Phase ◽  
Frame Building ◽  
Target Mode ◽  
The Difference ◽  
Displacement Based ◽  
Rc Frame Building ◽  
Shear Demand

An RC frame school building was designed with lower fortification requirements than required. It collapsed in the 2008 Ms8.0 Wenchuan earthquake. This study evaluated the building’s deficiency and practiced a retrofit design based on traditional demand-capacity method but with a displacement-based (DB) procedure, in which target capacities were obtained from the equivalent single-degree-of-freedom (ESDOF) systems defined by target mode shapes of the MDOF system, and shear demands were assessed using an R- μ- T relationship to match different capacity levels. To make the DB procedure code-conforming, the retrofitting elements (BRBs) were simplified as bi-linear elements, with the two-phase parameters corresponding to the code’s two-stage requirements. Shear distribution to the MDOF building was also determined by displacement shapes. BRBs’ stiffness demands and sizes were from the difference of the required and available shear resistances. The effectiveness of the method was validated by time history analyses. Different earthquake level simulations showed that, the method realized the design goals but did not lead to over-retrofitting; the BRBs took most of the shear demand but would not induce other unexpected failures. So the method was suitable for retrofitting similar structures.

scholarly journals Soil-pile-structure interaction effects on high-rise building under seismic shaking

2019 ◽  
Vol 2 (1) ◽  
pp. 153-164
Author(s):  
Umesh Jung Thapa ◽  
Ramesh Karki
Keyword(s):  
Soil Structure ◽  
Seismic Analysis ◽  
Time History ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Structure Interaction ◽  
High Rise ◽  
High Rise Building ◽  
History Analysis ◽  
Fixed Base

In this paper, study of the response (base shear, time period, storey drift, storey displacement) of a structure is done for the tall building including basement with fixed base and with pile foundation considering Soil Structure Interaction (SSI). Finite element based program ETABS2016 v16.1.0 is used for the analysis of the superstructure. Seismic analysis is done to get the dynamic response of superstructure for two types of model,one model is with fixed baseand second is Model with Winkler spring for Chhaya Center, Thamel, a high rise building with 14 story including double basements. Itisobserved with the consideration of Soil Structure Interaction (SSI). The soil is replaced by spring and assigned at joints. El Centro earthquake (1940) is used for time history analysis. The response obtained due to SSI effect is compared with fixed based model. Results of analysis presented include the comparison of natural periods, base shears, displacements and overturning moment. It is observed that the natural periods increase and the base shears decrease as the base become more flexible.

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