Prestressed concrete masonry walls subjected to uniform out-of-plane loading

1993 ◽  
Vol 20 (6) ◽  
pp. 969-979
Author(s):  
J. L. Dawe ◽  
G. G. Aridru
Keyword(s):  
Prestressed Concrete ◽  
Failure Load ◽  
Masonry Walls ◽  
Prestressing Force ◽  
Concrete Masonry ◽  
Ultimate Failure Load ◽  
Wall Stiffness ◽  
Out Of Plane ◽  
Ultimate Failure ◽  
Concrete Masonry Walls

Two series of post-tensioned concrete masonry walls subjected to uniform lateral loading were tested to investigate their flexural strength behaviour. Each series of walls consisted of four full-scale prestressed specimens, with varying levels of prestressing force, and one reinforced specimen. Of particular interest were the load–deflection curves, initial cracking loads, wall stiffness, crack patterns, and ultimate failure loads. An air bag test apparatus was used for applying lateral uniform pressures to the specimens. Results of this experimental investigation showed that, for a given wall thickness, increased prestressing force increases the cracking load, initial wall stiffness, and ultimate failure load. The results have established a linear relationship between increased prestressing force and initial cracking load, initial wall stiffness, and ultimate failure load. The proposed model, which takes into account changes in wall stiffness after initial cracking of the wall, accurately predicts wall behaviour. Key words: masonry, prestressed, walls, strength, behaviour, uniform, pressure, experimental, analytical.

Behaviour of hollow concrete masonry walls with one-course bond beams subjected to concentric and eccentric concentrated loading

2003 ◽  
Vol 30 (1) ◽  
pp. 181-190 ◽  
Author(s):  
Junyi Yi ◽  
Nigel G Shrive
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Three Dimensional ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Concentrated Load ◽  
Concrete Masonry ◽  
Out Of Plane ◽  
Concentrated Loading ◽  
Concrete Masonry Walls

Three-dimensional finite element models of unreinforced hollow concrete masonry walls with one-course bond beams subjected to concentrated loading have been analyzed. The walls were modelled with different loading plate sizes, different loading locations along the wall (at the midpoint of the wall, at the end of the wall, and between these points), and different out-of-plane eccentricities (e = 0, t/6, and t/3). The hollow block units, mortar, grout, and bond beam blocks in the walls were modelled separately. Both smeared and discrete cracking methods have been utilized for predicting cracking under load. Geometric and material nonlinearities and damage due to progressive cracking were taken into account in the analyses. The predicted failure modes and ultimate capacities of the walls with the concentric concentrated load applied at the midpoint or at the end of the wall compared very well with the experimental results. When the load was between the midpoint and the end of the wall, the predicted ultimate capacity was between those for the load at the midpoint and at the end. The strength of the walls decreases with increasing out-of-plane eccentricities.Key words: finite element models, hollow masonry, smeared and discrete cracking models, concentrated load, loading locations, out-of-plane eccentricities.

In-plane flexural strength of unbonded post-tensioned concrete masonry walls

2017 ◽  
Vol 136 ◽  
pp. 245-260 ◽  
Author(s):  
Reza Hassanli ◽  
Mohamed A. ElGawady ◽  
Julie E. Mills
Keyword(s):  
Flexural Strength ◽  
Masonry Walls ◽  
Concrete Masonry ◽  
Concrete Masonry Walls ◽  
Post Tensioned

scholarly journals Behavior of Partially Grouted Concrete Masonry Walls under Quasi-Static Cyclic Lateral Loading

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2424
Author(s):  
Sebastián Calderón ◽  
Laura Vargas ◽  
Cristián Sandoval ◽  
Gerardo Araya-Letelier
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Masonry Walls ◽  
Lateral Stiffness ◽  
Edge Elements ◽  
Vertical Reinforcement ◽  
Concrete Masonry ◽  
Resistance Degradation ◽  
Concrete Masonry Walls

Eight partially grouted (PG-RM) concrete masonry walls were tested to study the influence of the strength and width of blocks, the wall aspect ratio, the horizontal and vertical reinforcement ratio, and the presence of edge elements (flanges). The results were analyzed in terms of the failure mode, damage progression, shear strength, lateral stiffness degradation, equivalent viscous damping ratio, and displacement ductility. Additionally, the performances of some existing shear expressions were analyzed by comparing the measured and predicted lateral load capacity of the tested walls. Based on the results, a slight increment in the lateral stiffness was achieved when employing stronger blocks, while the shear strength remained constant. Besides, increasing the width of concrete blocks did not have a significant effect on the shear strength nor in the initial tangential stiffness, but it generated a softer post-peak strength degradation. Increasing the wall aspect ratio reduced the brittleness of the response and the shear strength. Reducing the amount of vertical reinforcement lowered the resulting shear strength, although it also slowed down the post-peak resistance degradation. Transversal edge elements provided integrity to the wall response, generated softer resistance degradation, and improved the symmetry of the response, but they did not raise the lateral resistance.

scholarly journals Different Suture Materials for Arthroscopic Transtibial Pull-out Repair of Medial Meniscal Posterior Root Tears: A Human Biomechanical Study

2019 ◽  
Vol 7 (9) ◽  
pp. 232596711987327
Author(s):  
Gilberto Y. Nakama ◽  
Zachary S. Aman ◽  
Hunter W. Storaci ◽  
Alexander S. Kuczmarski ◽  
Joseph J. Krob ◽  
...  
Keyword(s):  
Medial Meniscus ◽  
Failure Load ◽  
Clinical Care ◽  
Posterior Root ◽  
Clinical Failure ◽  
Postoperative Rehabilitation ◽  
Pull Out ◽  
Ultimate Failure Load ◽  
Ultimate Failure ◽  
Suture Tape

Background: Transtibial pull-out repair of the medial meniscal posterior root (MMPR) has been largely assessed through biomechanical studies. Biomechanically comparing different suture types would further optimize MMPR fixation and affect clinical care. Purpose/Hypothesis: The purpose of this study was to determine the optimal suture material for MMPR fixation. It was hypothesized that ultra high–molecular weight polyethylene (UHMWPE) suture tape would be biomechanically superior to UHMWPE suture and standard suture. Study Design: Controlled laboratory study. Methods: The MMPR attachment was divided in 24 human cadaveric knees and randomly assigned to 3 repair groups: UHMWPE suture tape, UHMWPE suture, and standard suture. Specimens were dissected down to the medial meniscus, and the posterior root attachments were sectioned off the tibia. Two-tunnel transtibial pull-out repair with 2 sutures, as determined by the testing group, was performed. The repair constructs were cyclically loaded between 10 and 30 N at 0.5 Hz for 1000 cycles to mimic the forces experienced on the medial meniscus during postoperative rehabilitation. Displacement was recorded at 1, 50, 100, 500, and 1000 cycles. Ultimate failure load, displacement at failure, and load at 3 mm of displacement (clinical failure) were also recorded. Results: UHMWPE suture tape had significantly less displacement of the medial meniscus when compared with standard suture at 1 (–0.22 mm [95% CI, –0.41 to –0.02]; P = .025) and 50 (–0.35 mm [95% CI, –0.67 to –0.03]; P = .029) cycles. There were no other significant differences observed in displacement between groups at any number of cycles. UHMWPE suture tape had significantly less displacement at the time of failure than standard suture (–3.71 mm [95% CI, –7.17 to –0.24]; P = .034). UHMWPE suture tape had a significantly higher load to reach the clinical failure displacement of 3 mm than UHMWPE suture (15.64 N [95% CI, 0.02 to 31.26]; P = .05). There were no significant differences in ultimate failure load between groups. Conclusion: The meniscal root repair construct with UHMWPE suture tape may be stronger and less prone to displacement than that with standard suture or UHMWPE suture. Clinical Relevance: UHMWPE suture tape may provide better clinical results compared with UHMWPE suture and standard suture.

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