I understand how to apply it, just not particularly to which items. Design of anchor reinforcement in concrete pedestals widianto, chandu patel, and jerry owen widianto is a structural engineer on the shell suex 1 project. Seismic stability properties of wood building materials. Overstrength factor and allowable stress design asce 705.
In aci 31811 and ascesei 710 an overstrength factor. Overstrength and ductility factors for steel frames. Seismic design of wood structures in the context of. Chapter 12 seismic design requirements for building. Scaling of base shear results of static and dynamic analysis. Asce 7 permits the use of the equivalent lateral force procedure for the design of most buildings, except. Seismic design specification for buildings, structures. Asce 7 16 established the acceptable collapse probabilities based on work reported in fema p695 quantification of seismic performance factors. What are the asce 710 seismic overstrength load combinations. Reinforced concrete frame members not designed as part of the seismic forceresisting system shall comply with section 21. The mapped peak ground accelerations in asce 7 10 fig. Equivalent lateral force procedure elf response is defined by two modes.
Seismic system factors and system overstrength strength of. Importance factors, ie, are shown in asce 710 table 1. Seismic design of nonbuilding structures structure magazine. We are going to cover the basics and some commentary. Where the design story drift is obtained from first order analysis, it should be increased by an incremental factor ad, or a p.
Lateral force design was carried out according to ascesei 710. Asce 7 minimum design loads for buildings and other structures, asce 7, 1998. These load combinations and their applicability are examined in section 2. For those who own a first or second printing, you may download a pdf file of the commentary for free from the asce website. The 2014 nehrp provisions will use asce 710 as the base document, making modifications. Seismic forceresisting system asce 7 section where detailing requirements are speci. Jan 05, 2018 frequently misunderstood seismic provisions of asce 7 10. Would someone please enlighten me as to the purpose of asce 7 10s seismic overstrength load combinations. Jul 03, 2019 pdelta effects must be considered, per section 12. Because earthquake loads together with the wind loads considerations have a huge impa. Accounting for ductility and overstrength in seismic. It is recommended that the user make use of the ascesei 710 expanded seismic commentary, which provides 5 pages of valuable background information.
Sfrs components that require application of the overstrength factor are defined in asce 7 minimum design loads for buildings and other structures and others are only found in the seismic provisions. Canada abstract the seismic behaviour factor, r, is a critical parameter in contemporary seismic design. Design examples seismic load analysis 9 95 asce 702 response parameters for. Pdf evaluation of overstrength factor of steel moment. Minimum design loads for buildings and other structures. Using the reliability procedures described in that publication, wellconfigured structural systems conforming to the requirements of asce 7 and its referenced standards can be shown to generally meet these. March 31, 20 use in conjunction with asce 7 10 second printing or with asce 7 10 first printing and errata 1 and 2. American society of civil engineers seismic subcommittee for asce 710. These values are much less than the strength capacity of the steel frames with considerable response modification factors which are the combination of. The level at which the horizontal seismic ground motions are considered to be imparted to the. Effects the stability coefficient, shall not exceed, max, value given by asce 7 eq.
It is recommended that the user make use of the asce sei 7 10 expanded seismic commentary, which provides 5 pages of valuable background information. When reinforcement is used to restraint concrete breakout, the overall anchorage. Values of f pga in the table are identical to the shortperiod site coefficient fa in asce 7 10 table 11. Ghosh 2014 61 values that have a 2% probability of being exceeded in 50. He is a member of the building seismic safety councils 2014 provisions update committee and of the american society of civil engineers seismic subcommittee for asce 710. Asce 716 provisions for lateral drift determination civil. Chapter 7 asce 710 design provisions for structures with passive energy dissipating systems 5.
Seismic design specification for buildings, structures, equipment, and systems. Significant changes from asce 705 to asce 710, part 1. Fema 451b topic 9 handouts seismic load analysis 2. The basic combinations for strength design with overstrength factor in lieu of equations 165 and 167 in section 1605. Chapter 12 seismic design requirements for building structures.
Are they to be applied just to the connections or to both connections and member design. Moore, a structural and civil engineering firm with offices nationwide. Design of anchor reinforcement in concrete pedestals widianto, chandu patel, and jerry owen. Asce 705 requirements for seismic design categories c and above where ductility. On the contrary, in the us codes there are factors that quantify separately the redundancy and overstrength of a structure. Ive not been able to find a good explanation of what these are used for. I was hoping i could get some input as to what items to pay atten. Asce 7 minimum design loads for buildings and other structures, american society of civil engineers, 1998. A seismic analysis in the design of buildings especially high rise towers is a very important factor to consider. The equivalent lateral force procedure is a linear static analysis technique that approximates nonlinear building response by use of the response modification factor r, which accounts for a buildings inherent ductility and overstrength. Correctly define the different spectral parameters used to define the seismic hazard in asce 7.
Asce 716 provisions for lateral drift determination. Differences in the ibc and ascesei 7 load combinations are covered in the following sections. Seiasce 702 minimum design loads for buildings and. When the new code came out 2006 ibc, some colleagues and i came to the conclusion that equations 58 of asce 12. It is incorporated in the third printing of ascesei 710 only. Ive been searching the web for a sort of comprehensive list of what elements get designed for the overstrength factor. Instructional material complementing fema 451, design examples seismic load analysis 9 7.
Structure magazine the most common errors in seismic design. The overstrength factor increases the required seismic forces and is applied in specific cases or in the design of certain parts of the structure. Chapter 7 the asce 710 design provisions for structures. Seismic design requirements, as stated in section 11. It is required where it is explicitly stated in the code.
Apr 02, 2015 ive been searching the web for a sort of comprehensive list of what elements get designed for the overstrength factor. Seismic load effects including overstrength factor 6. The omega overstrength factors should only be used where specifically. Asce 7 says, where specifically required so you simply have to keep your eyes open for references to section 12. Structure magazine seismic design of nonstructural. The connections of such discontinuous elements walls or frames to the. Use in conjunction with asce 710 second printing or with asce 710 first printing and. Pdf using inappropriate system overstrength factors may lead to weak seismic. Expanded seismic commentary asce 7 seismic provisions.
Structure magazine the most common errors in seismic. Fema 451b topic 9 handouts seismic load analysis 2 instructional material complementing fema 451, design examplesseismic load analysis 9 7. A guide for practicing engineers nist gcr 89171 jack p. It is incorporated in the third printing of asce sei 7 10 only. Evaluation of the overstrength factor for nonstructural.
Code considerations related to woodframe shear walls and diaphragms are discussed, including failure modes of wood shear walls and the detailing required to provide ductile behavior. Three seismicforceresisting coefficients are used to gauge the performance of these systems, helping designers and engineers select the right one for their application. Asce 7 groups woodframe seismicforceresisting systems table 12. Mandatory retrofit program for wood frame buildings with. Seismic system factors and system overstrength free download as powerpoint presentation. Chapter 7 the asce 710 design provisions for structures with. When using allowable stress design, factor of safety for soil bearing values shall not be less than the overstrength factor of the structures supported.
Seismic design of castinplace concrete diaphragms, chords. The results show that mrf, cbf, and semirigid steel frame would be subjected to a base shear up to 4. Pacific earthquake engineering research center guidelines for performancebased seismic design of tall buildings may 2017. Risk categories of buildings and other structures are shown in ibc table 1604. New concept used to approximate the combined effects of higher modes that may be significant to story velocity. Evaluation of overstrength factor of steel moment resisting. Asce 7 2006 associates the design hazard to the maximum considered earthquake mce which corresponds to 2% probability of exceedance in 50 years in most parts of the us, except in coastal california leyendecker et al. These studies have shown in their globality that the overstrength depends on different factors which the most important of them is member ductility factor. Earth retaining structures tanks and vessels telecommunication towers stacks and chimneys. Pdf use of overstrength and inelastic response in seismic design. Pdf evaluation of overstrength factor of steel moment resisting. Design loads for seismic design based on asce 7 05. A comparative study of design base shear for rc buildings.
Minimum design loads for building and other structures. Asce 7 2006 recommends a factor of 23 to reduce the mce to obtain the design hazard level. Recently, a study was conducted to investigate the overstrength factor of. Response modification factor of reinforced concrete moment resisting frames in developing countries by adeel zafar thesis submitted in partial fulfillment of the requirements for the degree of master of science in civil engineering in the graduate college of the university of illinois at urbanachampaign, 2009 urbana, illinois adviser. Table 1 horizontal earthquake acceleration values for experimental. Reflection amplification factor, cd, fot use in asce 710 sections 12. A guide for practicing engineers applied technology council. The most common errors in seismic design and how to properly avoid them thomas f. Shafts under lateral loads, users manual and technical manual. With the simplified procedure of asce 7, section 12.
The first mode effect is reduced by the rfactor of the seismic forceresisting system, but then amplified by the overstrength factor. March 31, 20 use in conjunction with asce 710 second printing or with asce 710 first printing and errata 1 and 2. Asce 7 05,1 the standard referenced in the 20062 and 20093 editions of the ibc, did not undergo the recently usual threeyear update. Loads and load distributions shall not be less than those given by asce 7 nehrp. Asce 7 10, aisc 36010, asic 34110, aci 31811 including chapter. Modern steel constructions monthly steel quiz tests your knowledge of steel design and. Frequently misunderstood seismic provisions of asce 710. Determine the elements that must be designed using the load combinations including the overstrength factor. Minimum design loads for building and other structures supplement no. An evaluation of overstrength factor of seismic designed low.
Clarification of the requirements for anchor overstrength and. I want to use allowable stress design in combination with the overstrength factor. Evaluation of overstrength factor of steel moment resisting frames. Design examples seismic load analysis 9 84 asce 705 ground motion selection. Seismic loads based on ibc 2012asce 710 based on section 16. Design of anchor reinforcement in concrete pedestals. The basic combinations for strength design with overstrength factor in lieu of equations 165 and 16 7 in section 1605. Seismic system factors and system overstrength strength. He is a member of the asce task committee on anchor rod design, and an associate member of the joint aci. Where the load combinations with overstrength factor in section 12. Pdf using inappropriate system overstrength factors may lead to weak seismic performance or uneconomic results. Application of overstrength factor how deep does it go.
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