Seismic requirements for wood building design recent. As observed, according to asce 7, the redundancy factor is taken into consideration to amplify or diminish seismic lateral forces based upon the seismic design category, which is a classification assigned to a structure based on its occupancy and the severity of the design earthquake ground motion at the site, as described in detail in sections. The chapter also discusses some additional points regarding the use of the redundancy factor. It is recommended that the user make use of the ascesei 710 expanded seismic commentary, which provides 5 pages of valuable background information.
The concept of a penalty factor for a lack of redundancy of load paths to transmit seismic forces from the floor mayjune 2004 97. Use of the redundancy factor seismic loads asce library. Guide to the seismic load provisions of asce 7 05 by finley a. I have a basic question that i dont think is explained well in the code that i wanted to see how you all handle it. Asce 716 provisions for lateral drift determination. Given this perspective, this seminar has been designed to provide guidance on how to use the code based procedures, while at the same time, providing sufficient technical background to. Seismic design shall include both effective from horizontal seismic and vertical seismic force.
Expanded seismic commentary asce 7 seismic provisions. For notional loads the option to consider with combinations containing only gravity loads should be selected if the largest ratio of secondorder drift over firstorder drift from step 6 is less than 1. Selected new provisions of asce 705 risk management. All four asce 7 options for building period determination are available here.
In fact, most of the building design results were govern with the seismic loads. In my opinion it appears that the redundancy factor check in asce 7 is most applicable to rigid diaphragm type buildings and that some. Depending on the seismic design category determined from the prior selections of occupancy, seismic ground motion and building system, the redundancy factor per asce will be shown here. Seismic system factors and system overstrength strength of. This standard, a complete revision of ascesei 702, includes. In a structural system without redundant elements, every element must remain. Seismic requirements for wood building design recent changes to asce 7 and ibc philip line, p. As mentioned in the previous article, seismic analysis. Chapter 12 seismic design requirements for building structures.
Minimum design loads for buildings and other structures provides requirements for general structural design and the means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, as well as their combinations, which are suitable for inclusion in building codes and other documents. Asce 705 redundancy factor flexible diaphragm structural. Diaphragm design forces i n seismic design, a diaphragm must be designed for the larger of the following two different design forces that are specified by the american society of civil engineers minimum design loads for buildings and other structures asce 705. Asce 705 redundancy factor flexible diaphragm jdgengineer structural op 25 feb 01. All diaphragms are semirigid, meaning that load is distributed to from the diaphragm to the vertical elements depends on the stiffness of the diaphragm and. Obtain the mapped mce spectral accelerations, ss and s1 2. Detached one and twostory woodframe dwellings generally have performed well even in. Introduction users of the 2006 international building code ibc will. In addition to the provisions, the documents below are referenced in this chapter. The inverted pendulum systems and cantilever column systems need additional development. Detailed comparison of structural provisions of 2005 asce 7 to 2003 nehrp continued 2003 nehrp 2005 asce 7 section provision section provision comments 4 earthquakes and for combinations of loads as indicated in this chapter.
Diaphragm flexibility rigid, flexible and semirigid. Oclcs webjunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus. Significant changes from asce 705 to asce 710, part 1. Structure magazine the most common errors in seismic design.
For the bridge, aashto seismic 2009 specified ductility demand less than 6 for bridges with multiple. List and summarize the four seismic analysis methods in asce 7. Structures assigned to seismic design category b or c. Seismic loads includes a frequently asked questions section and three. Wind load for main wind force resisting system enclosed and partially enclosed buildings. Structure magazine the most common errors in seismic. Modify the mce spectral accelerations to account for site specific soil characteristics sms and sm1. Minimum acceptable seismic resistance of existing buildings is a policy issue normally set by the authority having. E h is defined as f p for nonstructural components and e v is defined as 0. Reliable information about the coronavirus covid19 is available from the world health organization current situation, international travel. Shafts under lateral loads, users manual and technical manual.
Seismic loads includes a frequently asked questions section and three appendixes with supplementary material. Long period map new systems, revised r factors and limitations diaphragm assumptions redundancy factor. Separate 66, as it is commonly referred to as, was a landmark document which set forth earthquake design provisions which. Asce 7, aisc 360, and the direct analysis method in the ram. Seismic system factors and system overstrength strength. We recommend that you register using the same email address you use to maintain your asce member account. Assessment of redundancy in the seismic design of moment resisting reinforced concrete frames. Delivers a quick, efficient way to look up key design parameters specified by standard asce sei 7 10 and 7 16 through a webbased. Design wind pressure, p, equation 619 asce 705 design wind pressures and forces are determined per equations given in section 6. There has also been a difference in provisions between asce 705 and the 2006. This program allows the user to select only site classes a through e, since site class f requires sitespecific geotechnical investigation and dynamic site response analyses. University of minnesota 2005 structural engineering seminars.
Structures, asce 705 for earthquake loads and addition of. Seismic forceresisting system asce 7 section where detailing requirements are speci. In asce 7 it is a factor applied to seismic loads when certain low redundancy conditions are met. Determine the gust effect factor g, in accordance with asce 7 section 6. A joint committee of the san francisco section of asce and the structural engineers association of northern california began work on seismic design provisions which were published in 1951 as asce proceedingsseparate no. Because earthquake loads together with the wind loads have a huge impact on the design result.
To ascesei 705 this part of the 2009 nehrp recommended seismic provisions for new buildings and other structures presents. Minimum design loads for buildings and other structures. It is equal to the total unfactored vertical design load at and above each level times the design story shift times the seismic importance factor divided by the product of design story shear, story height below the level in consideration, and deflection. The height limits for ordinary reinforced masonry shear walls are too liberal in asce 7, going from np to 160 ft.
If you are not currently logged into asce, you will be asked to login or create an asce account. Displacementbased seismic analysis of a mixed structural. Multiply all dynamic displacements by cdr omitted in asce 705. Correctly calculate and apply the redundancy factors in load combinations with seismic forces. Displacementbased seismic analysis of a mixed structural system. Asce 7 05 web seminar jan30 free download pdf ebook.
Diaphragm design forces i n seismic design, a diaphragm must be designed for. Determine the elements that must be designed using the load combinations including the. Assessment of redundancy factors for the seismic design of. R response modification factor see step 12 t fundamental period of the structure see step ts s d1 s ds tl longperiod transition period asce figure 2215 8 or 12 seconds asce 705 section 12. Detailed comparison of structural provisions of 2005 asce. An important consideration when using an inelastic analysis is that the system must be sufficiently ductile to handle the continued application of loads after the lateral loadresisting elements begin to yield. Determine the elements that must be designed using the load combinations including the overstrength factor. University of minnesota 2005 structural engineering. Pdf assessment of redundancy in the seismic design of. The seismic force, e, appears in load combinations.
It is incorporated in the third printing of ascesei 710 only. Long period map new systems, revised r factors and limitations diaphragm assumptions. Design wind pressures and forces are determined per. Chapter 12 seismic design requirements for building. Design of members or connections where the seismic load effects including overstrength factor are required for design.
Determine the external pressure coefficients, cp, in accordance with asce 7 section 6. For other structures assigned to seismic design category d, and for. Significant changes to the minimum design load provisions of. In the lastpublished edition, asce american society of civil engineers 710,4 referenced by the 2012 ibc,5 major revisions have taken place in wind design, seismic design, and other provisions from asce 705. In my opinion it appears that the redundancy factor check in asce 7 is most applicable to rigid diaphragm type buildings and that some intrepation is needed to apply it to a flexible diaphragm. Nov 07, 2018 evaluate the stability coefficient for each level per equation 12. Ie occupancy importance factor see step 11 r response modification factor see step 12 t fundamental period of the structure see step ts s d1 s ds tl longperiod transition period asce figure 2215 8 or 12 seconds asce 7 05 section 12.
Introduction and basic structural dynamics learning outcomes. For those who own a first or second printing, you may download a pdf file of the commentary for free from the asce website. Numerous and frequentlyupdated resource results are available from this search. Design examples seismic load analysis 9 17 1a, 1b stiffness soft story irregularity. Ubc 97 provisions, the seismic analysis in the design of buildings especially high rise towers is a very important factor to consider.
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