SEISMIC DESIGN FACTORS FOR PRECAST CONCRETE SHEAR WALL PARKING GARAGES
Author: A. E. SCHULTZ , B. ERKMEN , R. A. MAGAÑA | Size: 0.43 MB | Format:PDF | Quality:Unspecified | Publisher: 13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2076 | Year: 2004 | pages: 15
This paper describes an analytical study for the evaluation of seismic design factors (R and Cd) for precast concrete shear wall structures used for parking garages. The study utilizes DRAIN-2DX models to represent the garages, in which precast concrete shear walls provide all resistance to lateral loads. The models were calibrated using experimental data from tests, and a parametric study of typical precast concrete parking garage structures was conducted to obtain the response modification factor, R, and displacement coefficient, Cd, as specified by 2000 provisions of the United States (US) National Earthquake Hazard Reduction Program (NEHRP) for use in seismic design practice [1]. The R and Cd factors were calculated using real-time, nonlinear, dynamic response of the parking garage structures obtained using DRAIN-2DX. The precast shear walls feature one of two types of primary reinforcement; unbonded post-tensioning bars, and partially debonded mild steel reinforcing bars. The study addresses variables that are recognized to affect nonlinear structural response, including seismic intensity and site conditions. The principal conclusion drawn from this study is that R and Cd values currently used for precast concrete shear wall buildings are acceptable, if not conservative, for seismic design practice
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Precast, prestressed wall panels comprising thin concrete sections are not commonly used as seismic shear walls. Many engineers and code officials view prestressed materials as nonductile, and the connections between the sandwich wall panels and the foundation may suffer from brittle joint failures. The authors have designed a new load-limiting foundation connection for precast, prestressed panels used as shear walls that prevents the development of excessive uplift forces in the joint. This connection allows precast, prestressed concrete wall panels, such as hollow-core, to act as shear walls in resisting seismic loading without relying on wall ductility or causing an anchorage failure in a thin concrete section of the wall panel (where a connector is located). This unique connector allows the wall system to behave unlike that anticipated by building-code-defined design methods. Building codes require the behavior of new systems to be compared (and proven similar) with that of code-conforming behavior before being used. This paper describes the development and testing of the proposed load-limiting connector and wall system and the wall design approach needed to obtain special building code approval for its use
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Article/eBook Full Name: Directional Moment Connections--A Proposed Design Method for Unbraced Steel Frames
Author(s): Disque, Robert O.
Published By: AISC
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Rock Engineering and Rock Mechanics: Structures in and on Rock Masses covers the most important topics and state-of-the-art in the area of rock mechanics, with an emphasis on structures in and on rock masses. The 255 contributions (including 6 keynote lectures) from the 2014 ISRM European Rock Mechanics Symposium (EUROCK 2014, Vigo, Spain, 27-29 May 2014) are subdivided under the following 10 headings:
- Rock properties and testing methods
- Rock mass characterization
- Rock mechanics for infrastructures
- Mining and quarrying rock mechanics
- Design methods and analysis
- Monitoring and back analysis
- Excavation and support
- Case histories and Preservation of natural stone
- Petroleum engineering, hydro-fracking and CO2 storage
- Applicability of EUROCODE-7 in rock engineering
Rock Engineering and Rock Mechanics: Structures in and on Rock Masses will be of interest to rock mechanics academics as well as to professionals who are involved in the various branches of rock engineering.
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Seismic design procedures were first incorporated in building design codes in the 1920s and 1930s when inertial loadings began to be appreciated. In the absence of reliable ground measurements during an earthquake as well as detailed knowledge of the dynamical response of structures, the seismic action was taken into account for design purposes as a statical horizontal force corresponding to about 10% of the weight of the structure.
By the 1960s ground measurements during an earthquake in the form of accelerograms were becoming more generally available. At the same time the development of strength design philosophies and of computer-based analytical procedures such as the spectral-modal analysis and the time-history analysis, facilitated the examination of the dynamical response of multi-degree-of-freedom structures (MDOF). According to these procedures, the calculations were carried out in a deterministic fashion. The response of the structure was assumed to be in the elastic range and the earthquake loading was taken into account considering the typical seismic intensity and soil nature of the site of the structure.
As the records of strong ground motion were increasing, it became apparent that the code provisions were inadequate in providing the required structural strength of the building to withstand an intense earthquake. This was recognized analysing the damage in structures that had been close to resonance. In fact the vibrating masses of structures in such a situation had often been exposed to accelerations from two to six times the maximum base acceleration that, of course, would induce forces on the structural elements much larger than expected in the design phase. However the lack of strength did not always result in failure and sometimes not even severe damage. On the other hand in specified regions of the structure (especially the ones with shear dominated behaviour) a rapid reduction in strength (brittle failure) was observed leading to local failure that often resulted in the formation of mechanisms and consequently collapse of the structure.
This type of observations called the attention of structural engineers to the property of the materials or of the structures to offer resistance in the inelastic domain of response. This property is generally known as ductility and includes the ability to sustain deformations in the inelastic range without significant loss of strength and a capacity to absorb energy by hysteretic behaviour
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I was browsing here as usual today only when I realised I have not seen some of my old friends here for long time. And I certainly not mean to coax for a new post/thread from them. They are some of my most respected users since I started here and I am wondering how are things going on their end? And yes, I checked their profile, some have been inactive for long but some was here just now!
In no particular hierarchy.
Robertsas: My fellow running moderator. Indonesian experienced engineer.
Ultra Zone
juice: A pioneer moderator
abudabeeja: A top book contributor prior to bookoz and libgen days. Quiet after a short moderating stint.
timosi: I don't know him well enough but once a great contributor as well.
Kamran: Pioneer and Mohsen's countrymate.
kowheng: Early days of experience sharing in his field, follow by a great period of moderating. The most consistent and ever present moderator I have seen in here.
struceng: One of the greatest users around. Very knowledgeable and helpful.
Flexi: One of the oldest VIP.
This is a friend and a fellow user saying Hello. By no means this thread mean to pressure you guys but please drop a line in this thread (of course you can PM me as well if you wish) when you are free to.
Till then, have a great day(or evening on your side) ahead!
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