his study first presents an extensive experimental research program on the true uniaxial and triaxial compression behavior for both high strength concrete (HSC) and steel fiber reinforced high strength concrete (SFHSC). The experimental study mainly focuses on the octahedral shear stress ~ strain relationship of those two types of concrete, which is adopted as the basis to develop a new incremental constitutive model. Emphasis is also put on the investigation of the variation of tangent Poisson's ratio under not only uniaxial but also triaxial stress conditions. The effect of cyclic loading on this parameter is also addressed.
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modular plastic hinge seismic special detail has been developed for use in steel special moment frames (SMFs). The aim of the special detail design is to dissipate seismic energy through stable yielding of a beam “link” in plastic hinge region. Reliable and repeatable energy dissipation at high ductility is assured through the elimination of weld failure modes, and the mitigation of local buckling and high multi-axis restraint. A casting process is used to configure the modular detail directly to meet these performance objectives. The primary features of the link region are an isolated flange with an integrally cast stiffener and a reduced section isolated web.
Two forms of the detail exist: a plastic hinge modular node (PH-MN) and a bolted alternative, the bolted plastic hinge connector (BPHC). The PH-MN, a “node” occupying the entire beam-to-column joint, was used to develop the concept. The PH-MN configuration removes the field weld from the critical cross-section, reduces triaxiality and eliminates through-thickness failure modes at the beam/column interface. The BPHC preserves the primary features of the PH-MN and provides performance at nearly the same efficiency, but, as a replaceable field-bolted component, is significantly more economical, improves modularity, and has certain practical advantages. A design procedure was developed to create a family of modular designs.
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A plastic hinge is a type of energy dampening device allowing plastic rotation
of an otherwise rigid column connection. This device is composed of a weakened portion
of the column prevented from rotating by relatively small steel members. These small
bars are designed to yield and allow rotation before the capacity of the column is reached,
thus acting as mechanical fuses protecting the column from fatigue. After a seismic event
the fuse bars can be easily replaced, restoring the column to its original condition. To
function properly the hinge must become plastic before the column above it yields, but
limiting the deflection at the top of the column is also desirable for the stability of the
overlying structure, necessitating a hinge with some degree of strength. The
experimental setup of this study was constructed in the University at Buffalo’s Structural
Engineering and Earthquake Simulation Laboratory in 2004 and was comprised of a steel
column subjected to lateral displacement at the top with a plastic hinge fixed at the base,
simulating earthquake-induced ground motion on a bridge column. The purpose of this
research was to develop an accurate model of the column-hinge system in the elastic
range of the fuse bars, allowing consideration of the above design criteria for later testing.
Plastic behavior of the fuse bars was not tested. Experimental data was generated using a
quasi-static cyclic loading pattern. The behavior of the system was shown to be in
agreement with the analytical model.
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Author: Carl T F Ross, T. Johns | Size: 457 KB | Format:HTML | Quality:Unspecified | Publisher: Taylor & Francis | Year: 1981 | pages: 97 | ISBN: 9780203472842
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As cold-formed steel decks are used in virtually every steel-framed structure for
composite slab systems, efforts to develop more efficient composite floor systems continues.
Efficient composite floor systems can be obtained by optimally utilizing the materials, which
includes the possibility of developing long span composite slab systems. For this purpose, new
deck profiles that can have a longer span and better interaction with the concrete slab are
investigated.
Two new mechanical based methods for predicting composite slab strength and behavior
are introduced. They are referred to as the iterative and direct methods. These methods, which
accurately account for the contribution of parameters affecting the composite action, are used to
predict the strength and behavior of composite slabs. Application of the methods in the
analytical and experimental study of strength and behavior of composite slabs in general reveals
that more accurate predictions are obtained by these methods compared to those of a modified
version of the Steel Deck Institute method (SDI-M). A nonlinear finite element model is also
developed to provide additional reference. These methods, which are supported by elemental
tests of shear bond and end anchorages, offer an alternative solution to performing a large
number of full-scale tests as required for the traditional m-k method. Results from 27 composite
slab tests are compared with the analytical methods
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An Analysis of Skewed Bridge/Vehicle Interaction Using the Grillage Method
Author: H. Zeng, J. Kuehn, J. Sun, H. Stalford | Size: 49 KB | Format:PDF | Quality:Original preprint | Publisher: H. Zeng, J. Kuehn, J. Sun, H. Stalford | pages: 6
The 1998 Bridge Inventory classified approximately 68,000 of the 280,000
American highway bridges as substandard. One way to extend the useful service life of a
bridge is to reduce peak vehicle loads. Field tests conducted at Walnut Creek Bridge on
Interstate 35 near Purcell, Oklahoma revealed that it is common for vehicles to exert peak
dynamic loads 1.3-1.7 times their static weights on the bridge. The focus of this work is
to model the dynamic interaction between vehicles and the bridge to facilitate the
development of strategies aimed at reducing dynamic loads applied to the bridge.
Walnut Creek Bridge is a two-lane, four-span, continuous steel girder bridge with a
reinforced concrete deck. The bridge structure is modeled as an assembly of grillage
members, consisting of longitudinal and transverse torsion beams. The finite element
model includes 205 nodes and 425 elements. The vehicle used in the analysis is a
36,000kg tractor-trailer, which is the heaviest vehicle allowed on this bridge without a
permit. The vehicle model is a 7 degree-of-freedom planar representation that accounts
for both the heave and pitch. The equations of motion of the vehicle and the bridge are
treated as two subsystems and are solved separately using the fourth order Runge-Kutta
integration method in state space. The compatibility equations at the interface between
the vehicle tires and bridge deck are satisfied by an iterative procedure.
The simulation results are compared to experimental results obtained by using a
tractor-trailer for both quasi-static and dynamic tests. A response of a typical point of the
bridge has a peak error of 8.2% and an RMS error of 12.4% for the quasi-static case, and
a 17.6% peak error and a 24.5% RMS error for the dynamic case, respectively. The close
agreement between the simulations and experiments enables a study of the influence of
various parameters which contribute to the response of the interacted system.
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Dealing with a wide range of non-metallic materials, this book opens up possibilities of lighter, more durable structures. With contributions from leading international researchers and design engineers, it provides a complete overview of current knowledge on the subject.
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This reviews the progress made worldwide in the use of fibre reinforced polymers as structural components in bridges until the end of the year 2000. Due to their advantageous material properties such as high specific strength, a large tolerance for frost and de-icing salts and, furthermore, short installation times with minimum traffic interference, fibre reinforced polymers have matured to become valuable alternative building materials for bridge structures. Today, fibre reinforced polymers are manufactured industrially to semi-finished products and complete structural components, which can be easily and quickly installed or erected on site
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Steel Corrosion in Concrete: Fundamentals and Civil Engineering Practice
Author: Arnon Bentur, Sidney Diamond, Neal Steve Berke | Size: 3.05 MB | Format:HTML | Quality:Unspecified | Publisher: Taylor & Francis | Year: 1997 | pages: 201 | ISBN: 9780203974643
Poor durability of concrete is a major cause of problems in modern building and civil engineering structures in all countries: the annual cost of investigating and repairing deteriorating reinforced concrete structures runs into many millions of pounds. This book explains the fundamentals of the corrosion of steel in concrete. It is comprehensive and provides a basis for the practising engineer to design concrete structures which avoid the problem using modern concepts and specifications. A limited discussion of corrosion measurement and repairs is also provided.
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As a desktop companion for project managers and engineers, contract administrators, cost scheduling engineers and others engaged in the oil and gas industry, pipeline and petrochemical construction this book covers the entire contract process, including: Efficient preparation of quotation requests as bid packages Examples for suitable contract formats Evaluation of bids Qualification of delay and disruption costs Contract closeout procedures Invoicing, progress payments and work break down structures Just to name a few topics.
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