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
Due to its simplicity, the structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of the nonlinear properties of each component in the structure, quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some programs based on the FEMA-356 and ATC-40 guidelines. While such documents provide the hinge properties for several ranges of detailing, programs may implement averaged values. The user needs to be careful; the misuse of default-hinge properties may lead to unreasonable displacement capacities for existing structures. This paper studies the possible differences in the results of pushover analysis due to default and user-defined nonlinear component properties. Four- and seven-story buildings are considered to represent low- and medium- rise buildings for this study. Plastic hinge length and transverse reinforcement spacing are assumed to be effective parameters in the user-defined hinge properties. Observations show that plastic hinge length and transverse reinforcement spacing have no influence on the base shear capacity, while these parameters have considerable effects on the displacement capacity of the frames. Comparisons point out that an increase in the amount of transverse reinforcement improves the displacement capacity. Although the capacity curve for the default-hinge model is reasonable for modern code compliant buildings, it may not be suitable for others. Considering that most existing buildings in Turkey and in some other countries do not conform to requirements of modern code detailing, the use of default hinges needs special care. The observations clearly show that the user-defined hinge model is better than the default-hinge model in reflecting nonlinear behavior compatible with the element properties. However, if the default-hinge model is preferred due to simplicity, the user should be aware of what is provided in the program and should avoid the misuse of default-hinge properties.
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