Seismic earth forces against embedded retaining walls

2016 ◽  
Vol 49 (2) ◽  
pp. 200-210
Author(s):  
C.Y. Chin ◽  
Claudia Kayser ◽  
Michael Pender
Keyword(s):  
Finite Element ◽  
New Zealand ◽  
Free Field ◽  
Retaining Walls ◽  
Finite Element Analyses ◽  
Ground Acceleration ◽  
Dynamic Finite Element ◽  
Acceleration Time Histories ◽  
Field Peak ◽  
Time Histories

This paper provides results from carrying out two-dimensional dynamic finite element analyses to determine the applicability of simple pseudo-static analyses for assessing seismic earth forces acting on embedded cantilever and propped retaining walls appropriate for New Zealand. In particular, this study seeks to determine if the free-field Peak Ground Acceleration (PGAff) commonly used in these pseudo-static analyses can be optimized. The dynamic finite element analyses considered embedded cantilever and propped walls in shallow (Class C) and deep (Class D) soils (NZS 1170.5:2004). Three geographical zones in New Zealand were considered. A total of 946 finite element runs confirmed that optimized seismic coefficients based on fractions of PGAff can be used in pseudo-static analyses to provide moderately conservative estimates of seismic earth forces acting on retaining walls. Seismic earth forces were found to be sensitive to and dependent on wall displacements, geographical zones and soil classes. A reclassification of wall displacement ranges associated with different geographical zones, soil classes and each of the three pseudo-static methods of calculations (Rigid, Stiff and Flexible wall pseudo-static solutions) is presented. The use of different ensembles of acceleration-time histories appropriate for the different geographic zones resulted in significantly different calculated seismic earth forces, confirming the importance of using geographic-specific motions. The recommended location of the total dynamic active force (comprising both static and dynamic forces) for all cases is 0.7H from the top of the wall (where H is the retained soil height).

scholarly journals Repeatability of Full-Scale Crash Tests and Criteria for Validating Simulation Results

1996 ◽  
Vol 1528 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Malcolm H. Ray
Keyword(s):  
Finite Element ◽  
Full Scale ◽  
Crash Test ◽  
Test Results ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Simulation Results ◽  
Crash Tests

A method of comparing two acceleration time histories to determine whether they describe similar physical events is described. The method can be used to assess the repeatability of full-scale crash tests and it can also be used as a criterion for assessing how well a finite-element analysis of a collision event simulates a corresponding full-scale crash test. The method is used to compare a series of six identical crash tests and then is used to compare several finite-element analyses with full-scale crash test results.

scholarly journals Numerical Modelling of Structures Adjacent to Retaining Walls Subjected to Earthquake Loading

Geosciences ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 486
Author(s):  
Xiaoyu Guan ◽  
Gopal S. P. Madabhushi
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Retaining Wall ◽  
Free Field ◽  
Retaining Walls ◽  
Earthquake Loading ◽  
Bending Moments ◽  
Sheet Pile ◽  
Novel Approach ◽  
Active Zones

In an urban environment, it is often necessary to locate structures close to existing retaining walls due to congestion in space. When such structures are in seismically active zones, the dynamic loading attracted by the retaining wall can increase. In a novel approach taken in this paper, finite element-based numerical analyses are presented for the case of a flexible, cantilever sheet pile wall with and without a structure on the backfill side. This enables a direct comparison of the influence exerted by the structure on the dynamic behaviour of the retaining wall. In this paper, the initial static bending moments and horizontal stresses prior to application of any earthquake loading are compared to Coulomb’s theory. The dynamic behaviour of the retaining wall is compared in terms of wall-top accelerations and bending moments for different earthquake loadings. The dynamic structural rotation induced by the differential settlements of the foundations is presented. The accelerations generated in the soil body are considered in three zones, i.e., the free field, the active and the passive zones. The differences caused by the presence of the structure are highlighted. Finally, the distribution of horizontal soil pressures generated by the earthquake loading behind the wall, and in front of the wall is compared to the traditional Mononobe-Okabe type analytical solutions.

Design of Extended Pile Shafts for the Effects of Liquefaction

2014 ◽  
Vol 30 (4) ◽  
pp. 1775-1799 ◽  
Author(s):  
Arash Khosravifar ◽  
Ross W. Boulanger ◽  
Sashi K. Kunnath
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Ground Motion ◽  
Nonlinear Dynamic ◽  
Soil Structure ◽  
Lateral Spreading ◽  
Earthquake Loading ◽  
Finite Element Analyses ◽  
Dynamic Finite Element ◽  
Parametric Analyses

An equivalent static analysis (ESA) procedure is proposed for the design of extended pile shafts subjected to liquefaction-induced lateral spreading during earthquake loading. The responses of extended pile shafts for a range of soil, structure and ground motion conditions were examined parametrically using nonlinear dynamic finite element analyses (NDA). The results of those parametric analyses were used to develop and calibrate the proposed ESA procedure. The ESA procedure addresses both the nonliquefaction and liquefaction cases, and includes criteria that identify conditions which tend to produce excessive demands or collapse conditions. The ESA procedure, its limitations, and issues important for design are discussed.

Validation of FMVSS201 Featureless Headform Finite Element Model for Rotational Acceleration

2001 ◽  
Author(s):  
Saeed D. Barbat
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Fe Model ◽  
Rotational Acceleration ◽  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Drop Tests ◽  
Constitutive Parameters

Abstract This paper demonstrates an application of the nine linear accelerometer scheme, proposed by (Padgaonkar et al., 1975), to the development and validation of a finite element model of a deformable featureless headform for rotational accelerations. Steps and procedures involved in the development and calibration of the model are also described. A set of tri-axial accelerometers was mounted at the headform center of gravity, C.G., which is located at the origin of the local coordinate axes of the headform. Three bi-axial accelerometers were also mounted at the front, left, and top of the headform’s aluminum skull and on the local coordinate axes of the physical headform. Nine linear accelerations were measured at the headform in drop tests against a rigid plate at impact speeds of 2.68, 4.0, 5.36, and 6.71 m/s (6, 9, 12, and 15 mph). The rotational accelerations of the headform were then calculated from the nine linear acceleration measurements. In the finite element (FE) model of the featureless deformable headform, a visco-elastic material law, available in the non-linear dynamic explicit code PAM-CRASH, was used to simulate the vinyl skin response during impact. The constitutive parameters of the headform’s skin material were calibrated through comparison of the headform drop simulations at various impact speeds with the corresponding tests. Headform responses, such as, resultant acceleration time histories at the headform C.G. and the rotational acceleration time histories obtained from the FE predictions of the headform responses during the drop tests simulations correlated very well with those obtained from experiments. Validation of the headform model for rotational accelerations provided higher level of confidence in the prediction capability of the model when used for interior head impact simulations with vehicle upper interior as specified by the Federal Motor Vehicle Safety Standard FMVSS 201.

Operations Management Strategy of Cable-supported Bridge using Seismic Accelerometer

2019 ◽  
Author(s):  
Seung Han Lee ◽  
Sung Woo Park ◽  
Kwang-Yeun Park ◽  
Do-Kyoun Kim ◽  
Byounghan Choi
Keyword(s):  
Operations Management ◽  
Disaster Response ◽  
Management Strategy ◽  
Response Spectrum ◽  
Free Field ◽  
Seismic Safety ◽  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Gyeongju Earthquake

<p>This study presents the operations management strategy to respond to earthquake disasters using the acceleration records measured by seismic accelerometers installed on the primary structural elements of cable-supported bridges and those on the free fields around them. A two-step strategy in operations management is proposed for the urgent seismic safety assessment. In the first step, the seismic safety is evaluated with respect to the peak values in recorded acceleration time histories at the locations of the pylon foundation of bridge and the free field around it, and the corresponding management criteria for them are determined based on the existing disaster response manual for offshore bridges. In the second step, the peak values in displacement time histories, which are estimated from the recorded acceleration time histories, are utilized to assess the seismic safety at locations of the top and middle of pylon, and the center of girder of bridge, and the corresponding management criteria are determined based on the structural analyses under the response spectrum seismic loading. When an earthquake occurs, the safety of cable-supported bridge is evaluated urgently through comparisons of peak values in the recorded acceleration time histories and the estimated displacement time histories with the management criteria of accelerations and displacements determined in advance, respectively. The validity of the proposed strategy is verified though performing the safety assessments for several cable-supported bridges on service in Korea using the acceleration data recorded during recent Gyeongju earthquake in Korea.</p>

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