Development of Seismic Force Reduction and Displacement Amplification Factors for Autoclaved Aerated Concrete Structures

2006 ◽  
Vol 22 (1) ◽  
pp. 267-286 ◽  
Author(s):  
Jorge L. Varela ◽  
Jennifer E. Tanner ◽  
Richard E. Klingner
Keyword(s):  
Reduction Factor ◽  
Test Results ◽  
Lateral Loads ◽  
Autoclaved Aerated Concrete ◽  
Laboratory Test Results ◽  
Seismic Force ◽  
Force Reduction Factor ◽  
Aerated Concrete ◽  
Hysteretic Characteristics ◽  
Force Reduction

This paper addresses the development and application of a rational procedure to select the seismic force reduction factor ( R) and the displacement amplification factor ( Cd) for the design of autoclaved aerated concrete (AAC) structures. The values of R and Cd are proposed based on a combination of laboratory test results and numerical simulation. The test results are obtained from 14 AAC shear-wall specimens tested under simulated gravity and quasi-static reversed cyclic lateral loads. Analytical responses are predicted using nonlinear analysis models whose hysteretic characteristics are based on the experimentally observed responses. Using an iterative procedure, typical AAC structures are designed using successively larger trial values of the factor, R, until the structure's response (either ductility or drift) exceeds the experimentally determined capacity. A lower fractile of those critical values, modified for probable structural overstrength, is taken as a reasonable value of 3 for R. Using an analogous procedure, a reasonable value of Cd is determined as 3. These values will undoubtedly be refined based on field experience, just as they have been for other structural systems.

An Evaluation of Two-Level Seismic Design Procedure

1993 ◽  
Vol 9 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Chia-Ming Uang
Keyword(s):  
Structural Damage ◽  
Limit State ◽  
Design Procedure ◽  
Reduction Factor ◽  
Performance Criteria ◽  
Ultimate Limit State ◽  
Seismic Codes ◽  
Seismic Force ◽  
Force Reduction Factor ◽  
Force Reduction

The two-level design philosophy is recognized by modern seismic codes. When this philosophy is implemented in the code, the intensities of the two design earthquakes, the structural performance criteria, explicit versus implicit design approach, and the effectiveness to achieve the performance criteria vary considerably from one code to the other. For the ultimate limit state, the UBC was compared with seismic codes of Canada, Japan, and Eurocode. It was found that a trend to deviate from the UBC approach of using a single seismic force reduction factor (i.e., Rw) is apparent. Instead, an approach using a compound force reduction factor which considers the contribution of structural ductility and structural overstrength is preferred. For the serviceability limit state, a comparison of the level of design earthquakes and performance criteria of the UBC, Tri-Services Manual, and the Japanese code indicates that the UBC produces the most flexible structure, and that UBC does not control structural damage. It is suggested that the UBC adopts an explicit serviceability design procedure.

Period-dependent seismic force reduction factors for short-period structures

1991 ◽  
Vol 18 (4) ◽  
pp. 568-574 ◽  
Author(s):  
W. K. Tso ◽  
N. Naumoski
Keyword(s):  
Reduction Factor ◽  
Structural Systems ◽  
High Ductility ◽  
Base Shear ◽  
Ductility Demand ◽  
Seismic Design Code ◽  
Short Period ◽  
Seismic Force ◽  
Force Reduction ◽  
Reduction Factors

The seismic force reduction factors proposed in the seismic provisions of the National Building Code of Canada 1990 (NBCC 1990) are examined using ground motion records from two recent Canadian earthquakes. The displacement ductility demands are analyzed for structural systems with different ductility capacity. It is found that the NBCC 1990 force reduction factors, which are period independent, lead to a very high ductility demand for short-period structural systems. To avoid this, two types of period-dependent force reduction factors for short-period structures are investigated. The results show that the linearly varying period-dependent reduction factor represents a viable means to resolve the high ductility problems associated with short-period structural systems. Key words: earthquake, seismic, design, code, response, spectra, ductility, reduction factor, base shear.

scholarly journals Further comments on seismic design loads for bridges

1981 ◽  
Vol 14 (1) ◽  
pp. 3-11
Author(s):  
J. B. Berrill ◽  
M. J. N. Priestley ◽  
R. Peek
Keyword(s):  
New Zealand ◽  
Response Spectra ◽  
Reduction Factor ◽  
Base Shear ◽  
Attenuation Model ◽  
Design Spectra ◽  
Model Code ◽  
Force Reduction Factor ◽  
Background Material ◽  
Force Reduction

This paper provides background material to the loadings section
of the model code recently published by the Society's Discussion Group
on Bridge Design, and presents a preliminary re-evaluation of the design spectra given in the proposed code. The basis for the proposed zoning scheme, in which the present uniform Zone B is replaced by a transition zone, is discussed. Arguments are given underlying the return period coefficients, and the force reduction factor used in generating the inelastic response spectra of the code. It is likely that the design spectra and the values of the other coefficients determining base shear forces will need to be revised as further research results become available; however, the form of the base shear expression, and the loadings section
as a whole, should remain unchanged. Re-evaluated spectra suggest that
the seismic coefficient values given in the proposed code may be too large by about 25 percent in Zone A, and too low by as much as 40 percent in
 Zone C. While the reassessed values should be more reliable than the original ones, they are based on a Japanese attenuation model, which has
not yet been calibrated against New Zealand data. Further research is required to establish an appropriate attenuation model for New Zealand;
 to avoid undue proliferation of design loadings it is preferable to defer revision of the various coefficients in the proposed code until such a
model is available. Until this is done, the proposed spectra should be viewed with caution, particularly in Zone C.

Effects of Waste Soda-Lime Glass Sand and Glass Fiber on Physical and Mechanical Properties of None-Autoclaved Aerated Concrete

2021 ◽  
Vol 1023 ◽  
pp. 141-146
Author(s):  
Inzhu Mukangali ◽  
Chang Seon Shon ◽  
Kirill Kryzhanovskiy ◽  
Di Chuan Zhang ◽  
Jong Ryeol Kim
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Physical And Mechanical Properties ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Test Results ◽  
Autoclaved Aerated Concrete ◽  
Glass Sand ◽  
Aerated Concrete ◽  
Compressive And Flexural Strengths

This paper investigates the combined effect of waste soda-lime glass sand and glass fiber on the physical and mechanical properties of none-autoclaved aerated concrete (NAAC). The use of both soda-lime glass sand and glass fiber can provide silica-rich materials in the aerated concrete and can enable the elimination of an autoclaved curing by enhancing the physical and mechanical properties in aerated concrete. In this study, a total of six mixture proportions were designed to evaluate these properties in NAAC. The mixture parameters included the partial substitutions of normal sand with soda-lime glass sand (0%, 15%, and 30%) and glass fiber (1%, 2%, and 3%). A series of tests were conducted to determine density, absorption, porosity, and both compressive and flexural strengths of the NAAC. Test results present that the increase of glass sand content leads to the increasing of both compressive and flexural strengths. Moreover, the combination of the use of glass sand with glass fiber also increases the strength up to 2 times (the mixture of 30% glass sand and 3% glass fiber). Furthermore, test results indicate the relatively good relationship between the density, porosity, and of NAAC with good accuracy.

Seismic shear demand of ductile cantilever walls: a Canadian code perspective

1994 ◽  
Vol 21 (3) ◽  
pp. 363-376 ◽  
Author(s):  
André Filiatrault ◽  
Danilo D'Aronco ◽  
René Tinawi
Keyword(s):  
Time History ◽  
Shear Walls ◽  
Analytical Investigation ◽  
Reduction Factor ◽  
Seismic Shear ◽  
Force Reduction Factor ◽  
Force Reduction ◽  
Shear Failures ◽  
Nonlinear Time History ◽  
Shear Demand

During severe earthquakes, ductile flexural walls are expected to exhibit inelastic flexural behaviour while other brittle deformation mechanisms, such as shear, should remain elastic. The philosophy of the Canadian seismic provisions for flexural walls is based on the assumption that the force reduction factor is applicable to both flexure and shear. If the bending moments are limited because of the flexural strength of a wall, then the shear forces are considered to be limited by the same ratio. Recent case studies have not confirmed this philosophy. Brittle shear failures in walls are still possible even if their shear strengths are established by the Canadian standards. This paper presents an analytical investigation on the shear demand of ductile flexural walls designed for three different seismic zones in Canada. For each zone, an ensemble of code compatible historical earthquake ground motions is identified. The shear demand of each structure, under each earthquake record, is obtained by nonlinear time-history dynamic analyses. In 77% of the cases, the computed dynamic shear demand is higher than the current code shear strength. To address this issue, a force modification factor for shear, different from the one for flexure, is suggested for the Canadian code. Key words: earthquake, seismic response, shear walls.

scholarly journals Force Reduction Factor R for Shear Dominated Low-Rise Brick Masonry Structures

2018 ◽  
Vol 2 (3) ◽  
pp. 14-29
Author(s):  
N. Ahmad ◽  
Q. Ali ◽  
M. Javed ◽  
◽  
◽  
...  
Keyword(s):  
Reduction Factor ◽  
Brick Masonry ◽  
Masonry Structures ◽  
Force Reduction Factor ◽  
Force Reduction

scholarly journals Geometric Parameters and Behavior Factor of Knee-Braced Steel Frames Using Nonlinear Static Pushover (NSP) Analyses

2016 ◽  
Vol 10 (11) ◽  
pp. 110
Author(s):  
Majid Anoushehei ◽  
Farhad Daneshjoo
Keyword(s):  
Steel Frames ◽  
Resistance Coefficient ◽  
Reduction Factor ◽  
Geometric Parameters ◽  
Braced Frame ◽  
Behavior Factor ◽  
Seismic Force ◽  
Force Reduction Factor ◽  
Nonlinear Static ◽  
And Behavior

During the recent years, the new knee-braced frame (KBF) system has been interested to achieve a proper seismic behavior. Briefly introducing KBF, the present study evaluates the geometric parameters and behavior factor of multi-story knee-braced steel frames. The studied models include three-, five- and eight-story steel CBFs, EBFs and KBFs. Using linear static analyses, the present study evaluates lateral stiffness of knee-braced frames and plots their co-stiffness curves. Using co-stiffness curves, then, the best range is determined for geometric parameters of KBFs to achieve the proper stiffness. In addition, ductility-related seismic force reduction factor (Rμ), incremental resistance coefficient (RS), and behavior factor (R) are calculated for the frames using incremental nonlinear static analyses, and compared with the corresponding concentric and eccentric frames.

Caltrans' New Seismic Design Criteria for Bridges

2000 ◽  
Vol 16 (1) ◽  
pp. 285-307 ◽  
Author(s):  
Mark Yashinsky ◽  
Thomas Ostrom
Keyword(s):  
Seismic Design ◽  
Nonlinear Behavior ◽  
Previous Method ◽  
Reduction Factor ◽  
Design Criteria ◽  
Structural Elements ◽  
Linear Elastic ◽  
Displacement Capacity ◽  
Force Reduction Factor ◽  
Force Reduction

Caltrans' Seismic Design Criteria (SDC) has been adopted as the minimum seismic standard for ordinary bridges on California's highways. The SDC is a compilation of new and existing seismic criteria that had been previously documented in a variety of Caltrans documents. The SDC extends the capacity design philosophy introduced in the 1980 Caltrans Bridge Design Specifications. The most significant departure from the previous procedure is that ductile members are now designed by comparing the displacement demand to the displacement capacity. The demands are generated by a linear elastic analysis, and the capacities are determined from a curvature analysis that incorporates the nonlinear behavior of the structural elements. The demand/capacity methodology supplants the previous method based on reducing the elastic dynamic forces by a force reduction factor. In this paper, the significant features of Caltrans' SDC are described.

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