Seismic Analysis and Design of Steel Liquid Storage Tanks
Author: Lisa Yunxia Wang | Size: 0.15 MB | Format:PDF | Quality:Unspecified | Publisher: California State Polytechnic University Pomona | Year: 2005 | pages: 7
Practicing engineers face many issues and challenges on the design and seismic evaluation of liquid storage tanks.
These challenges are generally either in the application of the current design codes and standards, or in choosing an
appropriate design method. This paper addresses the design issues on the liquid storage tanks especially on the steel tanks, and
the application of the ANSI/AWWA D-100 standard on the design of ground steel tanks.
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Earthquakes are natural phenomena, which cause the ground to shake. The earth’s
interior is hot and in a molten state. As the lava comes to the surface, it cools and new
land is formed. The lands so formed have to continuously keep drifting to allow new
material to surface. According to the theory of plate tectonics, the entire surface of the
earth can be considered to be like several plates, constantly on the move. These plates
brush against each other or collide at their boundaries giving rise to earthquakes.
Therefore regions close to the plate boundary are highly seismic and regions farther from
the boundaries exhibit less seismicity. Earthquakes may also be caused by other actions
such as underground explosions.
The Indian sub-continent, which forms part of the Indo-Australian plate, is pushing
against the Eurasian plate along the Himalayan belt. Therefore, the Himalayan belt is
highly seismic whereas peninsular India, which is not traversed by any plate boundary, is
relatively less seismic. Earthquakes became frequent after the construction of Koyna dam
and this is regarded as a classic case of man-made seismicity. However, the Latur
earthquake of 1993, which occurred in what was previously considered to be the most
stable region on the earth implies that no region is entirely safe from devastating
earthquakes.
Earthquakes cause the ground to shake violently thereby triggering landslides, creating
floods, causing the ground to heave and crack and causing large-scale destruction to life
and property. The study of why and where earthquakes occur comes under geology. The
study of the characteristics of the earthquake ground motion and its effects on engineered
structures are the subjects of earthquake engineering. In particular, the effect of
earthquakes on structures and the design of structures to withstand earthquakes with no or
minimum damage is the subject of earthquake resistant structural design. The secondary
effects on structures, due to floods and landslides are generally outside its scope.
The recent earthquake in Kutch, Gujarat on 26 Jan 2001 has not only exposed the
weaknesses in the Indian construction industry but also the lack of knowledge about
earthquake engineering among all concerned. Taking advantage of the fear caused by the
earthquake in the minds of both the common people and the engineering community, a
number of people who have no knowledge about earthquake engineering have made
totally absurd statements with regard to earthquake resistant design. Examples are given
below:
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SEISMIC LATERAL FORCE DISTRIBUTION FOR DUCTILITY-BASED DESIGN OF STEEL PLATE SHEAR WALLS
Author: SWAPNIL B. KHARMALE and SIDDHARTHA GHOSH | Size: 3.6 MB | Format:PDF | Quality:Unspecified | Publisher: Department of Civil Engineering Indian Institute of Technology Bombay | Year: 2011 | pages: 24
The thin unstiffened steel plate shear wall (SPSW) system has now emerged as a promising
lateral load resisting system. Considering performance-based design requirements,
a ductility-based design was recently proposed for SPSW systems. It was felt that a
detailed and closer look into the aspect of seismic lateral force distribution was necessary
in this method. An investigation toward finding a suitable lateral force distribution
for ductility-based design of SPSW is presented in this paper. The investigation is based
on trial designs for a variety of scenarios where five common lateral force distributions
are considered. The effectiveness of an assumed trial distribution is measured primarily
on the basis of how closely the design achieves the target ductility ratio, which is measured
in terms of the roof displacement. All trial distributions are found to be almost
equally effective. Therefore, the use of any commonly adopted lateral force distribution
is recommended for plastic design of SPSW systems.
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ROTATION CAPACITY AND OVERSTRENGTH OF STEEL MEMBERS FOR SEISMIC DESIGN
Author: Manuela Brescia | Size: 3.8 MB | Format:PDF | Quality:Unspecified | Publisher: iversità degli Studi di Napoli Federico II Facoltà di Ingegneria Dottorato di Ricerca in Ingegneria delle Costruzioni | pages: 214
Earthquake is generally considered the most destructive and frightening of all
forces of nature. It consists in sudden slippages or movements in a portion of the earth’s crust accompanied by a series of vibrations. After shocks with similar or minor intensity can follow the main quake. Earthquakes can occur at any time of the day, of the week, of the month and of the year. Every day small ground motions are registered in some parts of the world, but they have generally small intensities and do not cause great damages, while every year two or three strong earthquakes fill the mass media with dramatic accounts of human losses. Geologists have identified regions where earthquakes are likely to occur. With the increasing population of the world and urban migration trends, higher death tolls and greater property losses are more likely in many areas prone to earthquakes. At least 70 million people face significant risk of death or injury from earthquakes because they live in the 39 states that are seismically active. Deaths and injuries derived form earthquakes, vary according to a lot of factors, one of the most important is safety of structure in which people live. Often the real tragedy is that human losses are due not tothe earthquakes themselves but to the failure of the constructions. Actually, seismic design has brought a lot of progress into the engineering practice. The current work has the purpose to furnish a small contribute to the difficult topic of the structural behaviour under seismic actions. The attention is focused on Steel Moment Resisting Frames and in particular on the Member behaviour. Starting form the assumption that in modern design practice it is generally accepted that steel is an excellent material for seismic-resistant structures because of its strength, ductility and capability to withstanding substantial inelastic deformations, an experimental campaign on steel beams has been made. The principal scope of the work has been the revision of the
classification criteria of steel members actually adopted by seismic codes and the introduction of a new criterion which takes into account the principal factors that influence the structural response.
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Author: Ronald O. Hamburger Simpson Gumpertz & Heger, Inc. San Francisco, CA Niaz A. Nazir DeSimone Consulting Engineers San Francisco, CA | Size: 3.11 MB | Format:PDF | Quality:Unspecified
In many ways structural steel is an ideal material for the design of earthquake-resistant structures. It is
strong, light weight, ductile, and tough, capable of dissipating extensive energy through yielding when
stressed into the inelastic range. Given the seismic design philosophy of present building codes, which
is to rely on the inherent ability of structures to undergo inelastic deformation without failure, these are
exactly the properties desired for seismic resistance. In fact, other construction materials rely on these
basic properties of steel to assist them in attaining adequate seismic resistance. Modern concrete and
masonry structures, for example, attain their ability to behave in a ductile manner through the presence
and behavior of steel reinforcing. Timber structures derive their ability to withstand strong ground
motion through the ductile behavior of steel connection hardware, including bolts, nails, and various
steel straps and assemblies used to interconnect wood framing.
Steel is a mixture of iron and carbon, with trace amounts of other elements, including principally
manganese, phosphorus, sulfur, and silicon. Steel is differentiated from the earlier cast and wrought irons
by the reduced amounts of carbon relative to these other alloys and the reduced amounts of other trace
elements. These differences make steel both stronger and more ductile than cast and wrought irons, both
of which tend to be quite brittle. Although iron alloys have been in use for centuries, steel is a relatively
modern material. For practical purposes the advent of steel as a construction material can be traced to the mid-19th century, when Sir Henry Bessemer developed the iron-to-steel conversion process that
allowed production of steel in large quantities. Initial uses of steel were in the railroad industry, where
it was used extensively to produce rails, and for armaments, including rifle and gun barrels. Andrew
Carnegie imported the Bessemer process to the United States and constructed his first steel mill in 1870,
initially for rail and machinery production. By the 1890s, however, steel was being applied to building
construction and, with the advent of the elevator and high-rise construction, rapidly became the building
material of choice for the new generation of tall buildings. The same properties that make it a desirable
material for high-rise construction (light weight, strength, ease of fabrication and erection) also make it
a popular construction material for structures involving long, clear spans. Today it is used in a variety
of construction applications ranging from bridges to industrial plants to buildings.
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Seismic design repair and retrofit strategies for steel roof deck diaphragms
Author: John-Edward Franquet | Size: 10 MB | Format:PDF | Quality:Unspecified | Publisher: Department of Civil Engineering and Applied Mechanics McGill University, Montreal, Canada | Year: OCTOBER 2009
Structural engineers will often rely on the roof diaphragm to transfer lateral seismic loads to the bracing system of single-storey structures. The implementation of capacity-based design in the NBCC 2005 has caused an increase in the diaphragm design load due to the need to use theprobable capacity of the bracing system, thus resulting in thicker decks, closer connector patternsand higher construction costs. Previous studies have shown that accounting for the in-plane flexibility of the diaphragm when calculating the overall building period can result in lower seismic forces and a more cost-Efficient design. However, recent studies estimating the fundamental period of single storeystructures using ambient vibration testing showed that the in-situ approximation was much shorter than that obtained using analytical means. The difference lies partially in the diaphragm stiffness characteristics which have been shown to decrease under increasing excitation amplitude. Using the diaphragm as the energy-dissipating element in the seismic force resisting system has also been investigated as this would take advantage of the diaphragm’s ductility and limited overstrength; thus, lower capacity based seismic forces would result. An experimental program on 21.0m by 7.31m diaphragm test specimens was carried out so as to Investigate the dynamic properties of diaphragms including the stiffness, ductility and capacity.The specimens consisted of 20 and 22 gauge panels with nailed frame fasteners and screwed sidelap connections as well a welded and button-punch specimen. Repair strategies for diaphragms that have previously undergone inelastic deformations were devised in an attempt to restitute the original stiffness and strength and were then experimentally evaluated. Strength and stiffness experimental estimations are compared with those predicted with the Steel Deck
Institute (SDI) method.
A building design comparative study was also completed. This study looks at the difference in design and cost yielded by previous and current design practice with EBF braced frames. Two alternate design methodologies, where the period is not restricted by code limitations and where the diaphragm force is limited to the equivalent shear force calculated with RdRo = 1.95, are also used for comparison. This study highlights the importance of incorporating the diaphragm stiffness in design and the potential cost savings.
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Seismic Demands on Steel Braced Frame Buildings with Buckling-Restrained Braces
Author: Rafael Sabelli, Stephen Mahin and Chunho Chang | Size: 0.44 MB | Format:PDF | Quality:Unspecified
This paper highlights research being conducted to identify ground motion and structural
characteristics that control the response of concentrically braced frames, and to identify
improved design procedures and code provisions. The focus of this paper is on the seismic
response of three and six story concentrically braced frames utilizing buckling-restrained
braces. A brief discussion is provided regarding the mechanical properties of such braces and
the benefit of their use. Results of detailed nonlinear dynamic analyses are then examined for
specific cases as well as statistically for several suites of ground motions to characterize the
effect on key response parameters of various structural configurations and proportions.
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Posted by: TAFATNEB - 08-31-2013, 09:44 AM - Forum: Steel
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Seismic Design of Seismic-Resistant Steel Building Structures
Size: 2.1 MB | Format:PDF | Quality:Unspecified
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Posted by: TAFATNEB - 08-31-2013, 09:29 AM - Forum: Steel
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Seismic design of multi-story cold-formed steel buildings: the CFS-NEES archetype building
Author: N. Nakata , B. W. Schafer and R. L. Madsen | Size: 8.57 MB | Format:PDF | Quality:Unspecified | Publisher: Department of Civil Engineering, Johns Hopkins University, Baltimore, | pages: 11
Lightweight cold-formed steel (CFS) framing is an effective building solution for low and mid-rise structures. However, systems level response and component contributions
as well as their interactions such as those from lateral-load resisting systems, floor diaphragms, studs to track connections, etc., are not fully understood. Existing building codes for the CFS frame buildings are based solely on the stiffness of the lateral-load resisting frames and do not explicitly incorporate systems response. This paper presents the first-phase of a multi-year project aimed at generating knowledge
and tools needed to increase the seismic safety of CFS frame buildings. The first phase of the study focuses on the design, instrumentation plan, and preliminary analysis
of full-scale two-story CFS frame buildings that are tested on shake tables at University at Buffalo NEES Facility in the second phase. Design of the two-story CFS buildings incorporates a “state of the practice” ledger framing system that attaches
floor and roof joists to the inside flanges of the load-bearing studs via a combination of track and clip angles. The instrumentation plan for the shake table tests is
developed to capture both systems and component level response of the buildings. The preliminary analysis includes development of new modeling capabilities that incorporate
cross-section limit states (local and distortional buckling) into frame analysis engines such as OpenSees to enable more accurate incremental dynamic analysis.
This paper provides detailed design of a prototype CFS frame building and instrumentation plan for the shake table tests at Buffalo.
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TEST PROCEDURES FOR THE DETERMINATION OF THE DYNAMIC SOIL CHARACTERISTICS
Author: Project coordinator: Bernd Asmussen International Union of Railways (UIC) | Size: 4.9 MB | Format:PDF | Quality:Unspecified | Year: DECEMBRE 2011 | pages: 107
Accurate prediction of railway induced vibration and assessment of the efficiency of vibration mitigation measures within the RIVAS project requires detailed knowledge of the dynamic soil characteristics.
Within the frame of the project, it is assumed that the soil can be modelled as a layered elastic halfspace, where the material properties vary only in the vertical direction, and that small strain behaviour prevails in the case of railway induced vibrations with relatively low amplitude. Within each layer, linear elastic isotropic constitutive behaviour is assumed; anisotropic constitutive behaviour would better represent the formation process, but is not generally used in state-of-the-art numerical models and geophysical prospection methods. Apart from the layer thickness, five parameters need to be determined for each layer: the shear and dilatational wave velocity, the material damping ratios in shear and dilatational deformation, and the mass density. The depth upto which these parameters should be investigated depends on the lowest frequency of interest and on the soil profile (stiffness). After a brief description of wave propagation in elastic media and the dependence of the constitutive soil behaviour on the strain level, the report discusses classical laboratory and in situ tests, which results can be used for soil characterization and a first estimate of dynamic soil characteristics based on empirical relations. Main emphasis is going to a detailed description of small strain dynamic laboratory tests and seismic in situ tests that can be used to determine dynamic soil characteristics.
The report concludes with a recommended course of action to determine dynamic soil characteristics within the frame of the RIVAS project, which is minimally based on a study of geological maps and historical geotechnical investigations, a first estimate of dynamic soil characteristics using empirical relations, soil characterization (e.g. mass density) using classical soil mechanics tests and seismic in situ testing (a combination of surface wave and seismic refraction methods). If budget permits, it is further recommended to perform an intrusive in situ test (cross-hole, up-hole, down-hole or SCPT) in order to enhance profiling depth and resolution, as well as to perform dynamic laboratory tests on undisturbed samples to determine complementary dynamic soil characteristics and to evaluate their strain dependency.
It is emphasized that, within RIVAS, estimations of dynamic soil characteristics based on empirical relations cannot replace their determination by means of in situ or laboratory tests. It is further recommended that impact loads are also measured when performing seismic in situ tests, so that the transfer functions of the soil are available and can be used for validation of the dynamic soil characteristics derived from the test.
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