Fhwa nhi06089 8 shallow foundations soils and foundations volume ii 8 1 december 2006 chapter 8. Seismic events can induce significant lateral loads to deep foundations. Instructional materials complementing fema p751, design examples. Seismic bearing capacity of shallow foundations near rock. Seismic design of shallow foundations bearing capacity of soil pedro miguel sereno july 2016 abstract traditionally the verification on the bearing capacity of shallow foundation in a seismic situation is. The factored forces for the design of a sign post foundation are. Design issues in addition to the conventional design issues of axial load capacity, settlement, structural adequacy and durability under static imposed loadings, the design of deep foundations in seismic areas requires consideration of the following factors. As analytical capabilities have improved, primarily in the form of finite element analysis, the mathematical modeling of. Foundation engineeringi design of shallow foundations 62 combined footings are used when. No further instructions are given regarding the improvement depth, or what changes if the surface layer crust does not liquefy. Chapter 21 provides the minimum requirements for concrete foundations in seismic design categories d, e and f, which are similar to those provided in prior editions of the provisions. The design of shallow foundations subject to di fferent static loadings has been an important area of research for geotechnical engineers. Shallow foundations residential seismic resilience.
Pdf seismic bearing capacity of shallow foundations. However, those who are conversant with design of structures under seismic load might wonder as to what is so. Xiaoping zhou, xinbao gu, maohong yu and qihu qian, seismic bearing capacity of shallow foundations resting on rock masses subjected to seismic loads, ksce journal of civil engineering, 20, 1. Footings example 1 design of a square spread footing of a. Performancebased seismic design of shallow foundations. Not felt except by a very few under especially favorable circumstances. Seismic design updates for the california building code. In this paper, seismic bearing capacity factors for shallow strip foundations embedded in homogeneous c. Practical approaches to seismic design of deep foundations 2. In both cases, the possible loss of soil support during the earthquake due to liquefaction or partial loss of soil strength must be considered. Chapter 6 seismic design page 62 geotechnical design manual m 4603. Deep foundations distribute loads to deeper, more competent soils or. Griffiths, b xianyue zhang c a department of engineering mathematics, dalhousie university, halifax, ns b3j 2x4, canada. Pdf earthquake resistant design of shallow foundations.
Basics of frost protected shallow foundation design. The analysis and design of shallow foundations is not discussed in this manual. Future issues multiperiod design spectrum asce 722 performance of existing, vulnerable buildings performancebased design not life safety, but continued function for new buildings. Footings example 1design of a square spread footing of a sevenstory building design and detail a typical square spread footing of a six bay by five bay sevenstory building, founded on stiff soil, supporting a 24 in. Therefore, in this paper, a parametric calculation is conducted to estimate the permanent displacement of shallow foundations after earthquakes using a new macro element that has been developed by. To date there is little in the way of code recommendations to cover this, especially along the emerging trends of performance based design. Seismic design of highway bridge foundations 1986 shale. Seismic bearing capacity of shallow strip footings embedded. Determination of seismically induced soil liquefaction potential at proposed bridge sites 1977 seismic design. As noted in table 2, structures are assigned to a seismic design category based. This presentation will cover the background to the provisions in the eurocode related to shallow foundations and will take advantage of the rion antirion bridge, recently completed, to illustrate the foundation seismic design process. Seismic design of shallow and deep foundations request pdf.
The current emphasis of the series is on performancebased engineering of lifelines and building structures. Primarily, shallow foundations must be designed for the load combinations given in asnzs 1170 structural design actions, as amended by. Design and construction of shale embankments, summary 1980. Seismic design of shallow foundations bearing capacity of. Seismic design of buildings worked examples worked examples presented at the workshop ec 8.
The information is intended to be practical in nature, and to especially encourage the costeffective use of shallow foundations bearing on structural fills. Illustrations figures and tables are comprehensively referred to from the text. Analysis of the seismic bearing capacity of shallow foundations. Shallow foundations are susceptible to any seismic effect that changes the ground contour, such as settlement or lateral movement, or alters the bearing capacity of the upper soil, such as liquefaction. Once earthquake risk and site effects have been evaluated the foundation designer needs to proceed with the proportioning of the foundation. Seismic performance of strip foundations on liquefiable. Bridge approach embankments and fills through which cutandcover tunnels are constructed should be designed to remain stable during the design seismic event because. Foundations should be designed in accordance with the latest edition of the 2012 ibc or the 2012 irc and. A numerical study is performed using finiteelement limit.
The bottom of the footing is ft below finished grade. Load and resistance factor design of shallow foundations. Load and resistance factor design of shallow foundations against bearing failure gordon a. A shallow foundation transfers loads from a building into the upper layers of the ground rather than to a deeper soil or stratum like a deep foundation. Most of the codes around the world recommend an increase in allowable bearing capacity of soil by about 25% under seismic load combination for design of shallow foundations. Transfer of seismic forces strength and stiffness shallow and deep foundations elastic and plastic analysis. As analytical capabilities have improved, primarily in the form. The southwestern tip of indiana is close to the new madrid seismic zone, which generated the large earthquakes of 18111812. The gardening channel with james prigioni recommended for you. Thus, use 75% of seismic vertical reactions foundation design 17. Apr 19, 2016 details language english duration 9 mins format. For shallow foundations, reinforcement is designed to satisfy flexural demands.
Seismic design of shallow and deep foundations springerlink. Peer reports pacific earthquake engineering research center. In this chapter information about the building site and the building structure are combined and used to determine the size of footings, reinforcing for the foundation, and the size and spacing of anchorage used to tie the unit to the foundation. Modern seismic codes dictate that the use of shallow foundations on liquefiable soils may be considered only after appropriate ground improvement. Most of the codes around the world recommend an increase in allowable bearing capacity of soil by about 25% under seismic. Seismic design of foundations presents state of theart information which will be ideal for any student studying postgraduate civil engineering or structural engineering as well as researchers and practitioners working in the field of earthquake geotechnical engineering.
The peer reports series comprises stateoftheart research in earthquake engineering and related fields by the more than 150 expert members of the peer universities consortium. Anchorages shall assure equilibrium and have a sufficient capacity to adapt to the seismic deformations of the ground the distance l e between the anchor and the wall shall exceed the di tdistance l s, requidired for nonseiiismic ldloads. In commercial buildings, shallow foundations are commonly combined with groundimprovement techniques to increase the bearing strength of the soil below the foundation. Therefore, significant items in illustrations have only been given a page reference in the absence of their concomitant mention in the text referring to that illustration. Shallow foundation design flowchart define subsurface conditions and any geometric constraints determine depth of footing based on geotechnical bearing. The peer reports series comprises state of theart research in earthquake engineering and related fields by the more than 150 expert members of the peer universities consortium.
Improved understanding of liquefaction effects on shallow. Calibration of resistance factors for geotechnical seismic. In the case of foundations, structural engineers are challenging the geotechnical engineer to examine more closely seismic performance criteria for foundations. Recent research findings on the seismic behaviour of pile foundations are discussed along with the codal provisions for seismic design of pile foundations. Eurocode 8 is an exception and contains an extensive section on the design of foundations to resist earthquake.
Seismic design updates for the california building code dave baska phd, pe, ge, ceg. Seismic design of reinforced concrete mat foundations. Basics of frost protected shallow foundation design andrew j. In approaching the seismic retrofit design problem, it is clearly desirable in economic terms, to reduce the level of conservatism in all aspects of the design. Foundation analysis and desing foundation design 1. Pdf the state of the art in the seismic design of shallow foundations is developing towards a rational, although still simplified, analysis. During a seismic event, liquefactionsusceptible soils offer less lateral resistance as well as reduced shaft resistance to a deep foundation. Missouri university of science and technology scholars mine. A design case study is presented highlighting the key points to be considered for seismic design of pile foundation in liquefiable soil. Analysis of the seismic bearing capacity of shallow. Seismic design of shallow foundations civil engineering. However, those who are conversant with design of structures under seismic load might wonder as to what is so special about it. A guide for practicing engineers seismic design of reinforced concrete mat foundations has advanced significantly in the last twenty years. This chapter deals with the design of shallow and deep foundation under seismic load.
Seismic design of deep foundations introduction observations from recent earthquakes have shown that pile foundations are susceptible to significant damage when subjected to loads induced by large seismic events. Shallow foundations fhwa us department of transportation. Practical approaches to seismic design of deep foundations. Scribd is the worlds largest social reading and publishing site. Seismic design of foundations presents stateoftheart information which will be ideal for any student studying postgraduate civil engineering or structural engineering as well as researchers and practitioners working in the field of earthquake geotechnical engineering. Performancebased seismic design of shallow foundations 4 3. Reading assignment lecture notes other materials ch. Chapter 9 seismic design nysdot geotechnical page 96 november 4, 2015 design manual rev.
In the context of engineering practice, the problem of the seismic bearing capacity of shallow foundations has been solved indirectly, either due an increase of the static allowable soil pressures related to the probability of occurrence of the design earthquake or by adopting an equivalent pseudostatic approach. Fema 451b topic 14 notes foundation design 14 1 instructional materials complementing fema 451, design examples foundation design 141 foundation design proportioning elements for. Pdf enhanced seismic design of shallow foundations. However, this isnt the methodology proposed by ec85. Design and construction of compacted shale embankments 1975 shale. The circular presents state of thepractice guidance on the design of shallow foundation support of highway bridges. The circular presents stateofthepractice guidance on the design of shallow foundation support of highway bridges.
Seismic design of earthretaining structures and foundations. Seismic design of shallow foundations bearing capacity of soil pedro miguel sereno july 2016 abstract traditionally the verification on the bearing capacity of shallow foundation in a seismic situation is executed using a methodology based in the global safety factor concept. The paper will present recommendations on geotechnical resistance factors for seismic design that can be used to guide and calibrate future editions of civil design codes in canada. Shallow and deep foundations elastic and plastic analysis. The effects of earthquake excitation on the lateral response and the structural integrity of the foundation system. Seismic design of shallow foundations bearing capacity of soil. Introduction the seismic risk mitigation is one of the greate st challenges of the civil engineering and an. Conference paper pdf available december 2018 with 422 reads.
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