FURTHER PROBING OF THE SUITABILITY OF PUSH- OVER ANALYSIS FOR THE SEISMIC ASSESSMENT OF BRIDGE STRUCTURES
Author: ALESSIO LUPOI University of Rome “Sapienza”, Dpt. of Structural and Geotechnical Engineering, PAOLO FRANCHIN University of Rome “Sapienza”, Dpt. of Structural and Geotechnical Engineering, .PAOLO E. PINTO University of Rome “Sapienza”, Dpt. of Structural and Geotechnical Engineering, | Size: 0.67 MB | Format:PDF | Quality:Unspecified | pages: 16
The applicability of non-linear static analyses for the assessment of less-thanregular bridges has been subject of recent research by a number of authors ([11,13,14]), with mixed results. The study presented in the paper intends to provide a further example of application of the approach to a bridge whose characteristics are such as to test it in a rather extreme case. This is an existing important highway viaduct built in the sixties, of total length equal to 420m, with 11 spans of 33m each and a continuous RC deck pinned over the piers. These latter, whose height varies irregularly between 14m and 41m, consist of slender single-bay frames with intermediate transverse beams. Among the numerous proposals available, the multi-modal nonadaptive approach as proposed by Chopra et al. [4] has been chosen as the preferred compromise between accuracy and complexity. The selected structure is characterised by at least two modes providing comparable contributions to the transversal response. In view of the final comparison of the results with those from non-linear dynamic analyses, the critical question of the choice of the reference response dof to be monitored has been investigated as well as the approximation of the method as a function of the intensity of the seismic action (inducing a variable degree of inelasticity in the structure).
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Influence of Nonlinear SSI on the Seismic Response of Reinforced Concrete Multistory Frames
Author: E. Saez, F. Lopez-Caballero, A. Modaressi-Farahmand Razavi | Size: 0.57 MB | Format:PDF | Quality:Unspecified | Publisher: The 12 th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG) 1-6 October, 2008 Goa, India | Year: 2008 | pages: 8
In general, the soil-structure interaction effects are assumed beneficial in the and thus ignored. Nevertheless, a more precise knowledge of the expected structural seismic response can allow to reduce the cost of the structure and to improve the earthquake engineering practice. This paper concerns the assessment of the effects of non-linear soil behaviour on the structural seismic demand evaluation. Special emphasis is placed on
the modelisation hypothesis and its consequences on the predicted seismic response.
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SIMPLIFIED DYNAMIC ANALYSIS OF ECCENTRIC BUILDINGS WITH A SETBACK. 2: THE EFFECT OF STIFFNESS IRREGULARITY
Author: GEORGE K. GEORGOUSSIS* | Size: 0.22 MB | Format:PDF | Quality:Unspecified | Publisher: THE STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGS Struct. Design Tall Spec. Build. (2009) | Year: 2009 | pages: 16
The effect of stiffness irregularity is investigated in eccentric buildings with a setback. Stiffness irregularity is
assumed to be created when some of the lateral load resisting bents are curtailed at the top of the base structure.
The methodology suggested in the companion paper for assessing vibration frequencies, base shears and torques
is extended to include the effect of curtailed bents. Their contribution is evaluated by an indirect method after
the modal stiffness of the symmetrical counterpart structure is determined and the modal contribution of the full height bents is assessed by Southwell’s approach. A number of numerical examples, representing common types of building structures, are presented to illustrate the procedure and provide an insight into the response of such setback buildings. The results are compared with more accurate results obtained by three-dimensional dynamic analyses.
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This report provides technical information on pervious concrete’s application, design methods, materials, properties, mixture proportioning, construction methods, testing, and inspection.
The term “pervious concrete” typically describes a near-zero-slump, open-graded material consisting of portland cement, coarse aggregate, little or no fine aggregate, admixtures, and water. The combination of these ingredients will produce a hardened material with connected pores, ranging in size from 0.08 to 0.32 in. (2 to 8 mm), that allow water to pass through easily. The void content can range from 15 to 35%, with typical compressive strengths of 400 to 4000 psi (2.8 to 28 MPa). The drainage rate of pervious concrete pavement will vary with aggregate size and density of the mixture, but will generally fall into the range of 2 to 18 gal./ min/ft2 (81 to 730 L/min/m2). Pervious concrete is widely recognized as a sustainable building material, as it reduces stormwater runoff, improves stormwater quality, may recharge groundwater supplies, and can reduce the impact of the urban heat island effect.
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Progressive Collapse Simulation of Reinforced Concrete Structures: Influence of Design and Material Parameters and Investigation of the Strain Rate E.ects
Author: Berta Santafé Iribarren | Size: 5 MB | Format:PDF | Quality:Unspecified | Publisher: Université Libre de Bruxelles Royal Military Academy Faculty of Applied Sciences Polytechnical Faculty | Year: 2011 | pages: 188
The finite element formulation adopted here is based on a multilevel approach where the response at the structural level is naturally deduced from the behaviour of the constituents (concrete and steel) at the material level. One-dimensional nonlinear constitutive laws are used to model the material response of concrete and steel. These constitutive equations are introduced in a layered beam approach, where the cross-sections of the structural members are discretised through a finite number of layers. This modelling strategy allows deriving physically motivated relationships between generalised stresses and strains at the sectional level. Additionally, a gradual sectional strength degradation can be obtained as a consequence of the progressive failure of the constitutive layers. This means that complex nonlinear sectional responses exhibiting softening can be obtained even for simplified one-dimensional constitutive laws for the constituents. This numerical formulation is used in dynamic progressive collapse simulations to study the structural response of a multi-storey planar frame subject to a sudden column loss. The versatility of the proposed methodology allows assessing the influence of the main material and design parameters in the structural failure. Furthermore, the e.ect of particular modelling options of the progressive collapse simulation technique, such as the column removal time or the strategy adopted for the structural verification, can be evaluated. The potential strain rate e.ects on the structural response of reinforced concrete frames are also investigated. To this end, a strain rate dependent material formulation is developed, where the rate e.ects are introduced in both the concrete and steel constitutive response. These e.ects are incor-
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P-DELTA EFFECTS OX THE INELASTIC SEISMIC RESPONSE OF REINFORCED CONCRETE SHEAR WALL BUILDINGS
Author: JIANHUA TU DEPARTEMENT DES GÉNIES CIVIL, GÉOLOGIQUE ET DES MMES ÉCOLE POLYTECHNIQUE DE MONTRÉAL | Size: 7.2 MB | Format:PDF | Quality:Unspecified | Year: 2000 | pages: 193
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The proposal lateral load pattern for pushover analysis is given in two forms for symmetric concrete buildings: 1-(X/H) 0.5 for low-rise and mid-rise buildings, 2- Sin(ΠX/H) for high-rise buildings. These two forms give more realistic results as compared to conventional load patterns such as triangular and uniform load patterns. The assumed buildings of 4, 8, 12, 16, 20 and 30 story concrete buildings are special moment frame which have been designed according to 2800 standard. Then using conventional load patterns and proposal load patterns, the pushover analysis has been done and results have been compared with the outcomes of nonlinear time history analysis. Results show the accuracy of proposed load pattern in comparing to the load patterns proposed by standards such as FEMA356.
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Effectiveness of modified pushover analysis procedure for the estimation of seismic demands of buildings subjected to near-fault ground motions having fling step
Author: A. Mortezaei and H. R. Ronagh | Size: 6.3 MB | Format:PDF | Quality:Unspecified | Publisher: Nat. Hazards Earth Syst. Sci | Year: 2013 | pages: 15
Near-fault ground motions with long-period
pulses have been identified as being critical in the design of
structures. These motions, which have caused severe dam-
age in recent disastrous earthquakes, are characterized by a
short-duration impulsive motion that transmits large amounts
of energy into the structures at the beginning of the earth-
quake. In nearly all of the past near-fault earthquakes, signif-
icant higher mode contributions have been evident in build-
ing structures near the fault rupture, resulting in the migra-
tion of dynamic demands (i.e. drifts) from the lower to the
upper stories. Due to this, the static nonlinear pushover anal-
ysis (which utilizes a load pattern proportional to the shape
of the fundamental mode of vibration) may not produce ac-
curate results when used in the analysis of structures sub-
jected to near-fault ground motions. The objective of this pa-
per is to improve the accuracy of the pushover method in
these situations by introducing a new load pattern into the
common pushover procedure. Several pushover analyses are
performed for six existing reinforced concrete buildings that
possess a variety of natural periods. Then, a comparison is
made between the pushover analyses’ results (with four new
load patterns) and those of FEMA (Federal Emergency Man-
agement Agency)-356 with reference to nonlinear dynamic
time-history analyses. The comparison shows that, generally,
the proposed pushover method yields better results than all
FEMA-356 pushover analysis procedures for all investigated
response quantities and is a closer match to the nonlinear
time-history responses. In general, the method is able to re-
produce the essential response features providing a reason-
able measure of the likely contribution of higher modes in all
phases of the response
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Hi!
Does the old trick of moving time backwards work with demo versions that experies after 30 days?
Im interested in a prigram that still hasnt been cracked and would like to run a demo version 30 day trial (all features available).
Anyone has any experience before I try and start conting time
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