Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(Sustained loads). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


University of Western Ontario

1. Elaghoury, Ziad. Long-Term Deflections of Reinforced Concrete Beams.

Degree: 2019, University of Western Ontario

The CSA A23.3 code provisions compute the long-term deflection of reinforced concrete flexural members by applying a multiplier to the short-term deflection, essentially ignoring the creep and shrinkage characteristics of concrete. The CAC Concrete Design Handbook presents more elaborate methods, but fails to account for the factors that influence the creep and shrinkage of concrete. The four widely recognized models for computing creep and shrinkage strains yield predictions that differ by up to 30%. Studies by others to assess the accuracy of the models apply different of statistical analyses do different datasets and so yield contradicting outcomes, making it difficult to quantify the prediction error. Mechanics-Based Methods for computing long-term deflections based on first principles are proposed and used to derive Alternative Simplified Methods. The accuracy of existing and proposed methods is assessed by quantifying test/predicted ratios. The CAC Handbook Method yields mean test/predicted ratios ranging from 0.97 (conservative) to 1.34 (unconservative). The mean test/predicted ratio for the Mechanics-Based Method and the Alternative Simplified Method range from 0.92 to 0.94, and from 0.97 to 1.05, respectively. The A23.3 Multiplier Method overestimates the deflection of lightly-reinforced members.

Subjects/Keywords: Reinforced concrete; Long-term deflection; Time-dependent analysis of concrete; Concrete creep; Concrete shrinkage Short-term deflection; Bischoff’s Equation; Effective moment of inertia; Sustained loads; Structural Engineering

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Elaghoury, Z. (2019). Long-Term Deflections of Reinforced Concrete Beams. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/6496

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Elaghoury, Ziad. “Long-Term Deflections of Reinforced Concrete Beams.” 2019. Thesis, University of Western Ontario. Accessed October 19, 2019. https://ir.lib.uwo.ca/etd/6496.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Elaghoury, Ziad. “Long-Term Deflections of Reinforced Concrete Beams.” 2019. Web. 19 Oct 2019.

Vancouver:

Elaghoury Z. Long-Term Deflections of Reinforced Concrete Beams. [Internet] [Thesis]. University of Western Ontario; 2019. [cited 2019 Oct 19]. Available from: https://ir.lib.uwo.ca/etd/6496.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Elaghoury Z. Long-Term Deflections of Reinforced Concrete Beams. [Thesis]. University of Western Ontario; 2019. Available from: https://ir.lib.uwo.ca/etd/6496

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


New Jersey Institute of Technology

2. Gu, Song. Bi-axially loaded slender reinforced concrete columns subjected to sustained loads.

Degree: PhD, Civil and Environmental Engineering, 2002, New Jersey Institute of Technology

A generalized analytical approach is presented in this research to predict the behavior both of slender and short reinforced concrete columns under sustained biaxial eccentric load. The present analysis proposes equations established at a cross section of a reinforced concrete column by combining force equilibrium, constitutive law, and compatibility conditions. The strain and curvature of each section and the deflection of the column can then be obtained and resolved. The established creep computation models, recommended separately by American Concrete Institute (ACI) 209R-92 and the Comite' Euro-International du Be'ton (CEB)-FIP 1990 Model Code have been used to calculate creep and shrinkage for a member under a constant elastic compressive concrete strain for a given period. This present analysis also proposes a computerized method for time and strain adjustment. The Time and Strain Adjustment of Creep Method, combining a creep calculation with a constant elastic strain such as those mentioned above, the creep strain at each cross section can then be calculated, stored and adjusted to age of concrete, load changes and deflection modifications during each time increment phase. In the conventional load-deflection analysis process, with projected transformations, a spatial deflection curve is resolved into a couple of planar curves located separately in two orthogonal plans. Based on the force equilibrium equations of inner force at a column section, a set of three simultaneous non-linear differential equations are derived to establish the relationships between the planar curve functions with the eccentric load upon the top of column. Using the Green's Integral Formula, the strain and stress nonlinear functions and column section properties can be solely integrated into a few important coefficients of the differential equations. Thus, it makes the approach also suitable for columns with non-rectangular sections and any kinds of constitutive laws of materials. The presented rational computer analysis results have been compared with the existing bi-axial and uniaxial experimental data, which are available in literature. They indicate that the results from the proposed analysis correlate with experimental data well. Advisors/Committee Members: C.T. Thomas Hsu, Methi Wecharatana, Dorairaja Raghu.

Subjects/Keywords: Creep buckling; Stability analysis of sustained loads; Time-dependant behaviors of concrete long columns; Uniaxial-bending loads; Civil Engineering

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gu, S. (2002). Bi-axially loaded slender reinforced concrete columns subjected to sustained loads. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/528

Chicago Manual of Style (16th Edition):

Gu, Song. “Bi-axially loaded slender reinforced concrete columns subjected to sustained loads.” 2002. Doctoral Dissertation, New Jersey Institute of Technology. Accessed October 19, 2019. https://digitalcommons.njit.edu/dissertations/528.

MLA Handbook (7th Edition):

Gu, Song. “Bi-axially loaded slender reinforced concrete columns subjected to sustained loads.” 2002. Web. 19 Oct 2019.

Vancouver:

Gu S. Bi-axially loaded slender reinforced concrete columns subjected to sustained loads. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2002. [cited 2019 Oct 19]. Available from: https://digitalcommons.njit.edu/dissertations/528.

Council of Science Editors:

Gu S. Bi-axially loaded slender reinforced concrete columns subjected to sustained loads. [Doctoral Dissertation]. New Jersey Institute of Technology; 2002. Available from: https://digitalcommons.njit.edu/dissertations/528

3. Hamdy Mohamed Zawam, Mohamed. Long-term behaviour of GFRP prestressed concrete beams.

Degree: 2015, University of Waterloo

During the last two decades, fibre-reinforced polymer (FRP) composites have emerged as prom-ising materials that can be used in lieu of steel for reinforcing concrete structures due to their corrosion-resistant properties, their high tensile strength, and their high stiffness to weight ratio. FRPs have lower moduli of elasticity compared to steel which may lead to increased deflections and deformations of FRP reinforced structures unless section sizes are increased. To overcome this serviceability concern, FRP bars can be prestressed. Previous research has focused on the use of carbon and aramid fibre reinforced polymers (CFRPs and AFRPs) in prestressed concrete while less attention was given to glass fibre reinforced polymers (GFRPs) because they have high relaxation and are susceptible to creep rupture. As well, only very limited data on the long-term behaviour of GFRP prestressed concrete members under sustained and fatigue loads is available. Also, no design guidelines are provided by CAN/CSA-S806-12 or ACI 440.4R-04 for using prestressed GFRP bars in concrete members. This research study consisted of experimental and analytical phases, and was designed to assess the long-term properties of a concrete beams prestressed with a new generation of GFRP bars that are reported to have enhanced mechanical properties such that the bars are suitable for pre-stressed applications by overcoming the creep rupture and the relaxation problems (Weber and Baquero (2010). This study investigated the transfer length of the prestressed GFRP bars of diameters 12 mm and 16 mm in concrete. Most of the available research studied the transfer length of CFRP and AFRP tendons, and both CAN/CSA-S6-06 and ACI 440.1R-06 give equations for predicting the transfer length for these bar types only. The GFRP bars were prestressed to 40% of their ultimate capacity, which is more than the 25% pre-stressing limit at transfer that is set by CAN/CSA-S6-06 to avoid creep rupture. The effects of the prestressing level, the GFRP bar diameter and the concrete strength on the long-term behaviour of GFRP prestressed concrete were investigated. Twenty beams with dimensions of 150 x 255 x 3600 mm were cast and tested under different sustained load levels for 300 days. The long-term deflections, the concrete strains and the GFRP strains were monitored throughout the testing period. The main parameters considered were the diameter of the GFRP prestressing bars (12 mm and 16 mm), the prestressing level (0%, 25% and 40% of the ultimate strength), and the sustained load level (35%, 60%, and 80% of the ultimate capacity of the beam). Following the sustained loading phase, all beams were tested to failure in four- point bending. The transfer length measurements were taken for the prestressed beams, and data on the early relaxation of the GFRP bars was recorded for 277 hours. The experimental results showed that prestressing of GFRP bars significantly decreased the beams deflections, and the total and the concrete creep strains under service loading conditions.…

Subjects/Keywords: Fibre Reinforced Polymer; Sustained loads; Concrete unloading behaviour; GFRP creep; Long-term behaviour; Residual strength; Transfer length; Prestressed concrete

…23 Figure ‎ 2.13: Modeling concrete section under sustained loads ( Zamblauskaite et… …of GFRP prestressed concrete members under sustained and fatigue loads is available. Also… …sustained loads, and provided data about the transfer length of these bars. 1.3 Research… …sustained loads up to 50% of their ultimate strength without having creep rupture problems (… …them were loaded with sustained loads and six of them were not loaded. The GFRP bars were… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hamdy Mohamed Zawam, M. (2015). Long-term behaviour of GFRP prestressed concrete beams. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/9976

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hamdy Mohamed Zawam, Mohamed. “Long-term behaviour of GFRP prestressed concrete beams.” 2015. Thesis, University of Waterloo. Accessed October 19, 2019. http://hdl.handle.net/10012/9976.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hamdy Mohamed Zawam, Mohamed. “Long-term behaviour of GFRP prestressed concrete beams.” 2015. Web. 19 Oct 2019.

Vancouver:

Hamdy Mohamed Zawam M. Long-term behaviour of GFRP prestressed concrete beams. [Internet] [Thesis]. University of Waterloo; 2015. [cited 2019 Oct 19]. Available from: http://hdl.handle.net/10012/9976.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hamdy Mohamed Zawam M. Long-term behaviour of GFRP prestressed concrete beams. [Thesis]. University of Waterloo; 2015. Available from: http://hdl.handle.net/10012/9976

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.