scholarly journals The experimental investigation of the failure of load-bearing masonry walls supported by a deflecting structure

2020 ◽  
Vol 19 (3) ◽  
pp. 127-141
Author(s):  
Adam Piekarczyk
Keyword(s):  
Experimental Investigation ◽  
Early Stage ◽  
Masonry Walls ◽  
Vertical Load ◽  
Wall Surface ◽  
Vertical Deflection ◽  
Door Opening ◽  
Small Deflection ◽  
Masonry Units ◽  
Group 1

The paper presents selected results of tests of full-scale masonry walls linearly supported on a deflecting beam. The walls with thin bed joints and unfilled head joints were 4.55 m long and 2.45 m high, and were made of group 1 calcium silicate masonry units. The tests included walls with and without openings. The tests were carried out in a specially designated and constructed test stand, which allowed simultaneous vertical load on the upper edge of the wall and vertical deflection of the beam supporting this wall. During the test, measurements of mutual displacements of six points on the wall surface were carried out. On both faces of masonry specimens, the changes of the length of the measuring bases connecting these six points were recorded. Walls without openings were detached from the central part of the supporting beam at a deflection not exceeding 2 mm. Walls with one door opening also cracked at an early stage of tests. In this case, a detachment from the supporting beam and cracking at the ends of the lintel occurred because of the rotation of the pillars connected by the lintel above the opening. In walls with two door openings, first cracks were formed at the ends of lintels due to the rotation of pillars with a small deflection of the supporting beam, less than 3 mm. Whereas, in walls with door and window openings, first cracks occurred under the window and at the end of the lintel in the outer pillar of the wall.

scholarly journals Use of the AE Effect to Determine the Stresses State in AAC Masonry Walls under Compression

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3459
Author(s):  
Radosław Jasiński ◽  
Krzysztof Stebel ◽  
Paweł Kielan
Keyword(s):  
Ultrasonic Waves ◽  
Image Correlation ◽  
Masonry Walls ◽  
Acceptable Error ◽  
Compressive Stresses ◽  
Deformation State ◽  
Hydrostatic Stresses ◽  
Stress States ◽  
The Impact ◽  
Masonry Units

Safety and reliability of constructions operated are predicted using the known mechanical properties of materials and geometry of cross-sections, and also the known internal forces. The extensometry technique (electro-resistant tensometers, wire gauges, sensor systems) is a common method applied under laboratory conditions to determine the deformation state of a material. The construction sector rarely uses ultrasonic extensometry with the acoustoelastic (AE) method which is based on the relation between the direction of ultrasonic waves and the direction of normal stresses. It is generally used to identify stress states of machine or vehicles parts, mainly made of steel, characterized by high homogeneity and a lack of inherent internal defects. The AE effect was detected in autoclaved aerated concrete (AAC), which is usually used in masonry units. The acoustoelastic effect was used in the tests described to identify the complex stress state in masonry walls (masonry units) made of AAC. At first, the relationships were determined for mean hydrostatic stresses P and mean compressive stresses σ3 with relation to velocities of the longitudinal ultrasonic wave cp. These stresses were used to determine stresses σ3. The discrete approach was used which consists in analyzing single masonry units. Changes in velocity of longitudinal waves were identified at a test stand to control the stress states of an element tested by the digital image correlation (DIC) technique. The analyses involved density and the impact of moisture content of AAC. Then, the method was verified on nine walls subjected to axial compression and the model was validated with the FEM micromodel. It was demonstrated that mean compressive stresses σ3 and hydrostatic stresses, which were determined for the masonry using the method considered, could be determined even up to ca. 75% of failure stresses at the acceptable error level of 15%. Stresses σ1 parallel to bed joints were calculated using the known mean hydrostatic stresses and mean compressive stresses σ3.

Study on Deformation and Stress of CRCP under Concentrated Vertical Load with Hollow Foundation

2011 ◽  
Vol 250-253 ◽  
pp. 3415-3420
Author(s):  
Xiao Bing Chen ◽  
Xiao Ming Huang ◽  
Jin Hu Tong
Keyword(s):  
Equivalence Principle ◽  
Transverse Crack ◽  
Torsion Theory ◽  
Slab Thickness ◽  
Vertical Load ◽  
Effective Measure ◽  
Small Deflection ◽  
Half Wave ◽  
Elastic Thin Plate ◽  
Deflection Theory

Based on the equivalence principle, the concentrated vertical load which acts on the Continuously Reinforced Concrete Pavement(CRCP) transverse crack is translated into the equivalent half-wave sine load by Fourier transform. According to the translation principle of the force, the half-wave sine vertical load acting on the CRCP transverse crack is decomposed to the half-wave sine vertical load and the torsion force acting on the center of CRCP. Lastly, the deflection, torsional displacement and stress formulas of CRCP under the concentrated vertical load with hollow foundation are put forward, which is on the basis of the small deflection theory of elastic thin plate and torsion theory. The results show that increasing the slab thickness is the most effective measure to reduce maximal deflection, distortion displacement and stress of CRCP concentrated vertical load with hollow foundation.

scholarly journals Experimental investigation of the in-plane cyclic behaviour of calcium silicate brick masonry walls

2020 ◽  
Vol 18 (8) ◽  
pp. 3963-3994
Author(s):  
F. Messali ◽  
R. Esposito ◽  
G. J. P. Ravenshorst ◽  
J. G. Rots
Keyword(s):  
Experimental Investigation ◽  
Calcium Silicate ◽  
Brick Masonry ◽  
Masonry Walls ◽  
Cyclic Behaviour

scholarly journals Experimental Study on Seismic Strengthening of Confined Masonry Walls Using RPC

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Xin Wang ◽  
Shuming Li ◽  
Zhenli Wu ◽  
Fanyang Bu ◽  
Fei Wang
Keyword(s):  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Confined Masonry ◽  
Aspect Ratios ◽  
Lateral Strength ◽  
Cracking Pattern ◽  
Strengthening Technique ◽  
Reactive Powder ◽  
Effective Reinforcement ◽  
Masonry Units

Masonry structures without effective reinforcement are vulnerable to seismic excitation. An innovative strengthening technique was proposed for damaged and undamaged masonry walls. Six confined masonry units with two aspect ratios were tested under in-plane lateral cyclic loading, which consisted of two control walls, two original walls strengthened with reactive powder concrete (RPC-1), and two damaged walls repaired with RPC (RPC-2). The results of the specimens retrofitted with RPC demonstrated that the proposed technique significantly enhanced the seismic performance of masonry walls in terms of lateral strength, ductility, and energy dissipation. Furthermore, the two repaired specimens had a better distributed cracking pattern than the two strengthened specimens. The analysis of the results leads to a better understanding of the effect and mechanism of RPC seismic retrofitting for confined masonry walls.

scholarly journals Quality of life and pain in dogs with early-stage mammary tumours

2015 ◽  
Vol 63 (4) ◽  
pp. 451-457 ◽  
Author(s):  
Larissa C. Faustino ◽  
Maria Anete Lallo
Keyword(s):  
Quality Of Life ◽  
Early Stage ◽  
Descriptive Study ◽  
Pain Scale ◽  
Stage I ◽  
Mammary Tumour ◽  
Mammary Tumours ◽  
Group 2 ◽  
Group 1

Quality of life (QOL) was evaluated in bitches with mammary tumours (MTs) by applying a scale to assess QOL in dogs with pain secondary to cancer. Two groups were constituted: Group 1 with 80 bitches with MT, oncologically classified as stage I (mean age ± SD = 9.9 ± 3.8 years), and Group 2 consisting of 80 healthy bitches without MT (mean age: 7.7 ± 1.8 years). The results were based on responses from owners using a standardised, internationally accepted pain-scale questionnaire. This prospective and descriptive study showed that 63% of the dogs in Group 1 had a change in QOL due to the presence of MT. The risk of QOL impairment was 2.1 times higher in Group 1 animals than in bitches without MT. Mammary tumour increased the presence of pain 8.3 times and defecation difficulties 10 times. It can be concluded that even small MTs can elicit pain in dogs, which interferes with their quality of life.

Minimum vertical load on masonry walls - a realistic view / Mindestauflast auf Mauerwerkswänden - eine realitätsnahe Betrachtung

Mauerwerk ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 245-257 ◽  
Author(s):  
Michael Schmitt ◽  
Carl-Alexander Graubner ◽  
Valentin Förster
Keyword(s):  
Masonry Walls ◽  
Vertical Load ◽  
Realistic View
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