Crack Propagation in Compression and Mounted Arrestors

2014 ◽  
Vol 624 ◽  
pp. 595-602 ◽  
Author(s):  
Susanna Casacci ◽  
Angelo Di Tommaso ◽  
Cristina Gentilini
Keyword(s):  
Tensile Strength ◽  
Numerical Model ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Masonry Walls ◽  
Masonry Structures ◽  
High Tensile Strength ◽  
Steel Bars ◽  
Out Of Plane ◽  
Compressive Loads

Strengthening of masonry walls is a key aspect during building retrofitting operations having conservation goals. “Reinforced repointing technique” involves the application of materials having high tensile strength such as steel bars, steel textile sheets or composites thin pultruded laminae with cracks arrestors function, to reduce the vulnerability of masonry structures against in-plane and out-of-plane actions. In this paper, a three-dimensional numerical model is developed to evaluate the efficiency of reinforcing steel bars facing crack propagation phenomenon under increasing compressive loads.

scholarly journals Wire Ropes and CFRP Strips to Provide Masonry Walls with Out-Of-Plane Strengthening

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2712
Author(s):  
Elena Ferretti
Keyword(s):  
Steel Wire ◽  
Three Dimensional ◽  
Maximum Load ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Wire Ropes ◽  
Out Of Plane ◽  
Beam Mechanism ◽  
Combined Technique ◽  
The Ideal

The present paper deals with an improvement of the strengthening technique consisting in the combined use of straps—made of stainless steel ribbons—and CFRP (Carbon Fiber Reinforced Polymer) strips, to increase the out-of-plane ultimate load of masonry walls. The straps of both the previous and the new combined technique pass from one face to the opposite face of the masonry wall through some holes made along the thickness, giving rise to a three-dimensional net of loop-shaped straps, closed on themselves. The new technique replaces the stainless steel ribbons with steel wire ropes, which form closed loops around the masonry units and the CFRP strips as in the previous technique. A turnbuckle for each steel wire rope allows the closure of the loops and provides the desired pre-tension to the straps. The mechanical coupling—given by the frictional forces—between the straps and the CFRP strips on the two faces of the masonry wall gives rise to an I-beam behavior that forces the CFRP strips to resist the load as if they were the two flanges of the same I-beam. Even the previous combined technique exploits the ideal I-beam mechanism, but the greater stiffness of the steel wire ropes compared to the stiffness of the steel ribbons makes the constraint between the facing CFRP strips stiffer. This gives the reinforced structural element a greater stiffness and delamination load. In particular, the experimental results show that the maximum load achievable with the second combined technique is much greater than the maximum load provided by the CFRP strips. Even the ultimate displacement turns out to be increased, allowing us to state that the second combined technique improves both strength and ductility. Since the CFRP strips of the combined technique run along the vertical direction of the wall, the ideal I-beam mechanism is particularly useful to counteract the hammering action provided by the floors on the perimeter walls, during an earthquake. Lastly, when the building suffers heavy structural damage due to a strong earthquake, the box-type behavior offered by the three-dimensional net of straps prevents the building from collapsing, acting as a device for safeguarding life.

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.

Typical brick masonry walls reinforced with high-strength mortar and steel bars in the horizontal joints

2021 ◽  
pp. 136943322110122
Author(s):  
Xinqiang Yao ◽  
Bin Liang ◽  
Hai Zhang ◽  
Ziliang Zhang ◽  
Zheng He
Keyword(s):  
Cement Mortar ◽  
High Strength ◽  
Shear Capacity ◽  
Brick Masonry ◽  
Masonry Walls ◽  
Masonry Structures ◽  
Test Plan ◽  
Static Tests ◽  
Rural Buildings ◽  
Steel Bars

Based on investigation of rural buildings in china, there are more than 20% of the masonry structures constructed in 1970s. Thus, the old blue bricks (OBB) and old red bricks (ORB), which demolished from the typical brick masonry structures was built in 1970s, was chosen in the test. During demolishing the OBB and ORB, the original mortar was destroyed. Thus, the 1:7.8 cement mortar was chosen instead of original mortars and the 1:5 cement mortar was chosen as the reinforcement mortar. In order to know the performant of the reinforcement methods, there are three-level test plan was put forward in the study. Firstly, the mechanical properties of OBB and ORB and mortars was tested; Secondly, the experiment tested the shear strength of the reinforced and unreinforced masonry specimens along mortar joints; Thirdly, there are four walls (OBB reinforced wall and unreinforced wall, ORB reinforced wall and unreinforced wall) have been made for the pseudo-static tests. This research conducted physical performance tests on masonry bricks, masonry components, and masonry walls of typical masonry structures. Through experiments, the shear capacity of the masonry structure reinforced by high-strength mortar and steel bars can be obtained.

scholarly journals Combined Strengthening Techniques to Improve the Out-of-Plane Performance of Masonry Walls

2019 ◽  
Author(s):  
Elena Ferretti ◽  
Giovanni Pascale
Keyword(s):  
Flexural Strength ◽  
Three Dimensional ◽  
Experimental Results ◽  
Masonry Walls ◽  
Mechanical Coupling ◽  
Out Of Plane ◽  
Combined Technique ◽  
The Ideal

The purpose of this study is to improve the performance of walls under out-of-plane loads, particularly when subjected to the hammering action of the floors. The idea behind the paper is to provide the masonry walls with a device that behaves like a buttress, without having to build a traditional buttress. The solution presented here consists of a mechanical coupling between the three-dimensional net of steel ribbons of the CAM system and the CFRP strips. Since the steel ribbons of the CAM system have a pre-tension, the mechanical coupling allows the steel ribbons to establish a semi-rigid transverse link between the CFRP strips bonded on two opposite sides of a wall. Therefore, two vertical CFRP strips tied by the steel ribbons behave like the flanges of an I-beam and the flexural strength of the ideal I-beam counteracts the out-of-plane displacements of the wall. The experimental results showed that the combined technique inherits the strong points of both constituent techniques: the delamination load is comparable to that of the specimens reinforced with the CFRP strips and the overall behavior is ductile as for the specimens reinforced with the CAM system. They also allowed us to design a more performing combined technique.

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