ABSTRACT
In common practice, the seismic design of an embedded retaining wall is carried out using the pseudo-static method. In this approach, constant forces are introduced in a limit equilibrium calculation, and the seismic analysis of a retaining wall is treated similarly to the evaluation of the safety against a collapse mechanism. This paper is aimed to propose a reconsideration of the simple pseudo-static calculation: it shows that the method can be used within the context of the performance-based design to predict the actual seismic performance of the wall, and that concepts employed in the capacity design of structural members can be extended to the design of embedded retaining walls. The paper also points to possible code prescriptions that may provide guidance for the correct application of the pseudo-static method to the design of retaining walls.
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A review of design methods for retaining structures under seismic loadings
Author: C. Visone & F. Santucci de Magistris Structural and Geotechnical Dynamic Lab StreGa, University of Molise, Termoli (CB), Italy | Size: 274 KB | Format:PDF | Quality:Unspecified | Year: 2008 | pages: 14
ABSTRACT: The earth retaining structures frequently represent key elements of ports and harbors, transportation
systems, lifelines and other constructed facilities. Earthquakes might cause permanent deformations of
retaining structures and even failures. In some cases, these deformations originated significant damages with
disastrous physical and economic consequences. For gravity walls, the dynamic earth pressures acting on the
wall can be evaluated by using the Mononobe-Okabe method, while Newmark rigid sliding block scheme is
suitable to predict the displacements after the shaking, as demonstrated by several experimental tests. Instead,
this simplified approach is not very useful for embedded retaining walls for various reasons. Many researchers
are interested to this topic. Advanced numerical analyses, centrifuge modeling, in-situ monitoring of full-scale
model are the main developing research activities on this subject. Here, after a brief review on the fundamental
seismic earth pressures theories, the application of the pseudostatic approach to the analysis of embedded
retaining walls, as prescribed by the European Codes, is highlighted. Finally, some considerations on the certain
limitations of this approach is done and the indications given by the latest Italian Building Codes (D.M
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Assessment of the modes of failure of retaining structures from previous major earthquakes: Caltrans Seismic Design Analysis of Retaining Walls Project
Author: Tadei Shayo Home Institution: UC Davis REU Institution: UCSD (Shake Table) REU Advisor: Prof. Lijuan (Dawn) Cheng, UC Davis Graduate Student Mentor: Erin Mock, UC Davis | Size: 968 KB | Format:PDF | Quality:Unspecified | Year: 2009 | pages: 21
The report herein is part of a larger project; the objective of the larger project is to improve the seismic design guidelines for highway retaining walls. For the large project, two specimens of
full-scale, reinforced concrete gravity retaining walls were constructed according to the current building code of The California Department of Transportation (Caltrans). The specimens will undergo shake table test at NEESinc’s Englekirk Center for Structural Engineering facility. The testing protocols to be used are the 1994 California Northridge (Mw= 6.7) and the 1999 Turkey Izmit/Kocaeli (Mw=7.4) earthquakes. The structural performance of the retaining walls after testing will thus be analyzed and used to make changes to the current design code. For this secondary project, assessment of the modes of failure of retaining walls from previous significant earthquake is done. A discussion is given regarding the correlations between the modes of failure and earthquake characteristics. Finally, recommendations as to which types of
reinforcing techniques are most effective in resisting seismic loads are given.
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SEISMIC ANALYSIS OF RETAINING WALLS WITHIN PLASTICITY FRAMEWORK
Author: T.Kalasin and D. Muir Wood | Size: 310 KB | Format:PDF | Quality:Unspecified | Publisher: The 14 th World Conference on Earthquake Engineering October 12-17, 2008, Beijing, China | Year: 2008 | pages: 11
Aseismic design of gravity wall still is a more difficult issue. The reason stems from the complexity of the problem which requires skills in soil mechanics, foundation engineering, soil-structure interaction along with knowledge of structure dynamics. Designing seismic gravity retaining structures deals with both kinematic interaction and inertial interaction but almost seismic building code neglected the soil-structure interaction by using the fixes base analysis of the structure. The gravity walls are a slender tall structure
and it was suggested to be taken into account of dynamic soil-structure interaction analysis because such walls often perform badly when subjected to strong earthquake ground motion. Also the permanent displacement should be evaluated when designing the seismic gravity walls so that the need of the most reliable approach to evaluate a wall’s vibration properties is required. In this paper, the alternative development of computed permanent responses was proposed in order to predict permanent responses of the
seismic wall. The proposed model was constructed within the concept of macro-element modelling the soil, foundation and the seismic earth pressures. The constitutive law for modelling soil and foundation were based on two-surface kinematic hardening with associated flow rule. The development of seismic earth pressures was based on the Mononobe-Okabe method (1929) and the elastic–perfectly plastic method (Muir Wood and Kalasin(2004)) which based on the kinematic hardening by updating of a reference position for the wall. A parametric study is presented and The results are compared with published experimental results.
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Evaluation of the seismic performance of a three-story ordinary moment-resisting concrete frame
Author: Sang Whan Han ; ∗; † , Oh-Sung Kwon and Li-Hyung Lee | Size: 346 MB | Format:PDF | Quality:Unspecified | Publisher: EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS Earthquake Engng Struct. Dyn. 2004; 33:669–685 (DOI: 10.1002/eqe.367) | Year: 2004 | pages: 17
This study focuses on the seismic performance of Ordinary Moment-Resisting Concrete Frames (OM- RCF) designed only for gravity loads. For this purpose, a 3-story OMRCF was designed in compliance with the minimum design requirements in the American Concrete Institute Building Code ACI 318
(1999). This model frame was a regular structure with exure-dominated response. A 1=3-scale 3-story model was constructed and tested under quasi-static reversed cyclic lateral loading. The overall behavior of the OMRCF was quite stable without abrupt strength degradation. The measured base shear strength was larger than the design base shear force for seismic zones 1, 2A and 2B calculated using UBC
1997. Moreover, this study used the capacity spectrum method to evaluate the seismic performance of the frame. The capacity curve was obtained from the experimental results for the specimen and the demand curve was established using the earthquake ground motions recorded at various stations with dierent soil conditions. Evaluation of the test results shows that the 3-story OMRCF can resist design seismic loads of zones 1, 2A, 2B, 3 and 4 with soil types SA and SB. For soil type SC, the specimen was satisfactory in seismic zones 1, 2A, 2B and 3. For soil type SD, the OMRCF was only satisfactory for seismic zones 1 and 2A.
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Author: Anil K. CHOPRA ___ Rakesh K. GOEL | Size: 251 KB | Format:PDF | Quality:Unspecified | Publisher: roceedings of the SEAOC Convention to be held in San Diego, California, 2001 | pages: 15
Evaluated is the accuracy of the modal pushover analysis in estimating the seismic demands for six
SAC buildings. These results are compared with those obtained by nonlinear response history
analysis and three force distributions in FEMA-273.
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INFLUENCE OF THE STORY STIFFNESS OF REINFORCED CONCRETE FRAME WITH PROPORTIONAL HYSTERETIC DAMPERS ON THE SEISMIC RESPONSE
Author: Juan andrés OviedO* | Size: 2.9 MB | Format:PDF | Quality:Unspecified | Publisher: Revista EIA, ISSN 1794-1237 Número 17, p. 121-137. Julio 2012 Escuela de Ingeniería de Antioquia, Medellín (Colombia) | Year: 2012 | pages: 17
This paper investigates the influence of the story stiffness of reinforced concrete (R/C) frame on the seismic
response of R/C buildings with proportional hysteretic dampers. For this purpose, non-linear time-history analyses
were conducted on a series of multi-degree-of-freedom system models that include a wide range of structural
parameters and vertical distributions of story stiffnesses and strengths of R/C main frame and dampers. Although
the basic purpose of damper installation is to reduce deformation demands, the results of analyses indicate that
the story-drift demand on an entire system could be larger than that of the structure without dampers, depending
highly on the stiffness and response period of R/C main frame. Moreover, dampers are shown to be more efficient
in reducing the story-drift demand when installed into a flexible R/C main frame.
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SEISMIC PERFORMANCE OF STORY-DRIFT-CONTROLLED REINFORCED CONCRETE FRAMES WITH HYSTERETIC DAMPERS
Author: Juan Andres OVIEDO-AMEZQUITA Candidate for the Degree of Doctor of Engineering Supervisor: Professor Mitsumasa MIDORIKAWA Division of Architectural and Structural Design | Size: 327 KB | Format:PDF | Quality:Unspecified | pages: 6
In the passive control of building structures, hysteretic
dampers are the most prevalent structural members
installed into a building to improve its seismic
performance through dissipating most of the vibration
energy imposed by ground motions.
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DESIGN DRIFT REQUIREMENTS FOR LONG-PERIOD STRUCTURES
Author: Gary R. Searer and Sigmund A. Freeman | Size: 96 KB | Format:PDF | Quality:Unspecified | Publisher: 3th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 3292 | Year: 2004 | pages: 9
The code provisions for calculating the design seismic drift of buildings have been substantially revised over the past 40 years. While these changes in the code are fairly well documented, the reasons behind these changes and the consequences of the changes are not as well known. This paper presents a brief history of design drift requirements, technical background for the requirements, and the reasoning behind the changes, starting with the 1961 Uniform Building Code (UBC) through present day. Emphasis is given to the discussion of minimum base shears for calculation of drift for long-period structures. Specifically, in Section 1630.10.1 of the 1997 UBC, it is not immediately apparent why Equation 30-6 may be disregarded in the calculation of drift while Equation 30-7 may not, since both equations tend to give very similar minimum base shears for typical buildings. In prior versions of the UBC, the minimum design base shear was determined by only one equation that could be disregarded during determination of drift. This paper discusses the reasoning behind Equation 30-7 in the current UBC and discusses the current controversy and differences of opinion regarding this equation. Also discussed are equivalent requirements in the National Earthquake Hazards Reduction Program (NEHRP) and Minimum Design Loads for Buildings and Other Structures (ASCE 7-02), which require a similar minimum base shear for determining drift of long period structures.
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A simple procedure to estimate the local displacement demands in regular frame-type structures that respond in elastic limits
is described. Given the spectral displacement and beam-to-column stiffness ratio, the procedure estimates the maximum ground story and maximum interstory drifts along the height of the structure. A total of 145 near-fault ground motions recorded on dense-to-firm soil sites are used for the evaluation of the procedure. The approximate drift demands computed from this procedure and the exact results from 27,550 response history analyses are used for calculating the error statistics. The calculations show that the procedure can be used with confidence for frames with fundamental periods between 0.3 and 1.5 s when they are subjected to near-fault records without pulse. The approximations are in good agreement with the exact response history results of near-fault records with pulse when the fundamental period to pulse period ratio is less than 1.5. The performance of the new procedure is also compared with other approximate methods that
are employed for similar purposes. The method can be useful for preliminary design of new structures or rapid assessment of existing buildings.
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Control of Seismic Drift Demand for Reinforced Concrete Buildings with Weak First Stories
Author: Manabu Yoshimura 1) 1) Department of Architecture, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji, Tokyo, | Size: 730 KB | Format:PDF | Quality:Unspecified | Publisher: Earthquake Engineering and Engineering Seismology, Vol. 4, No. 1 | Year: | pages: 9
This paper studies seismic drift demand for RC buildings with weak first stories, the potential seismic vulnerability of which has been revealed in many past earthquakes including the 1995 Kobe and 1999 Chi-Chi earthquakes. In a building that collapsed during the Kobe earthquake the strength balance between the first story and the upper stories is shown to have had a significant effect on the collapse of this building. Nonlinear dynamic analyses are then conducted for a model representing weak-first-story buildings to study the first story drift demand, where the first-story strength and the strength balance along the height are taken as analysis variables. Based on the results,
conditions that the two parameters should satisfy for controlling the first-story drift demand within an allowable level are discussed.
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