Simulation of earthquakes on strengthened masonry walls: photogrammetric determination of kinematic shape changes

1994 ◽  
Author(s):  
Gregor Schwegler ◽  
J. Dold
Keyword(s):  
Masonry Walls ◽  
Shape Changes

Analytical modeling of masonry load-bearing walls

2003 ◽  
Vol 30 (5) ◽  
pp. 795-806 ◽  
Author(s):  
Yi Liu ◽  
J L Dawe
Keyword(s):  
Flexural Rigidity ◽  
Computer Application ◽  
Masonry Walls ◽  
Load Bearing ◽  
Analytical Technique ◽  
Reinforced Masonry ◽  
Material Stiffness ◽  
The Moment ◽  
Magnification Effect

An analytical technique was developed and encoded for computer application to study the behaviour of concrete masonry load-bearing walls under various loading conditions. Both geometrical and material nonlinearities to account for the moment magnification effect and the degradation of material stiffness are included in the development. Effects of vertical reinforcing steel, masonry tensile cracking, and compressive crushing are included directly in the moment–curvature relationship, which is used in the determination of element stiffnesses at successive load increments. A parametric study was conducted following verification of the analytical model by comparing results with experimental test data. Effective flexural rigidity (EIeff) values at failure were obtained analytically and compared with values suggested in the Canadian masonry code CSA-S304.1-M94. It was concluded that CSA-S304.1-M94 tends to underestimate EIeff values for reinforced walls and thus leads to a conservative design over a range of parameters. Based on approximately 500 computer model tests, a lower bound bilinear limit for the effective rigidity of reinforced masonry walls was established. This limit is believed to provide an accurate and realistic estimate of EIeff.Key words: walls, load bearing, masonry, analytical, nonlinear, rigidity, stress–strain, moment–curvature.

Destructive Tests for the Determination of Masonry Performance

2009 ◽  
Vol 417-418 ◽  
pp. 753-756
Author(s):  
Lucio Nobile ◽  
Cristina Gentilini ◽  
Veronica Bartolomeo ◽  
Mario Bonagura
Keyword(s):  
Mechanical Properties ◽  
Experimental Research ◽  
State Of The Art ◽  
The State ◽  
Masonry Walls ◽  
Compression Tests ◽  
Diagonal Compression

Several masonry panels are studied by means of destructive tests such as compressive, diagonal compression and shear-compression tests. The experimental research allows to characterize the mechanical properties of masonry walls in order to assess the masonry performance. Moreover, a brief recall of the most important experimental progress is presented in order to understand the state of the art of the research in the field of destructive tests.

scholarly journals Effects of Polypropylene Fibers and Measurement Methods on the Yield Stress of Grouts for the Consolidation of Heritage Masonry Walls

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 53 ◽  
Author(s):  
Luis G. Baltazar ◽  
Fernando M. A. Henriques ◽  
Maria Teresa Cidade
Keyword(s):  
Yield Stress ◽  
Load Capacity ◽  
Measurement Methods ◽  
Stone Masonry ◽  
Masonry Walls ◽  
Polypropylene Fibers ◽  
Shear Strain Rate ◽  
Hydraulic Lime ◽  
Structural Deterioration

The injection of grouts is a consolidation technique suitable for overcoming the structural deterioration of old stone masonry walls. Grouting operations involve introducing a suspension (grout) into a masonry core with the aim of improving the load capacity of the wall, as well as reducing its brittle mechanisms. The yield stress of injection grouts will affect the injection pressure and their flow inside the masonry. However, the determination of some rheological properties such as yield stress in hydraulic grout is challenging, due to the combined effects of hydration reactions and interactions between the particles present in the suspension. In this study, the determination of the yield stress of natural hydraulic lime-based grouts with polypropylene fibers was carried out. The changes in yield stress with time, fibers content and hydration were evaluated by two measurement methods using a rotational rheometer. Additionally, the static and dynamic yield stress as well as the critical shear–strain rate were determined, which provided useful information on the grout design in order to achieve successful grouting operations.

Pressure-Induced Metabolic Activation of Platelets Demonstrated In Vitro by Determination of Malondialdehyde Formation

1984 ◽  
Vol 52 (01) ◽  
pp. 004-006 ◽  
Author(s):  
Alessandro Torsellini ◽  
Luca Doni ◽  
Wulf Palinski ◽  
Giovanni Guidi ◽  
Valeriano Lombardi
Keyword(s):  
Arachidonic Acid ◽  
Atmospheric Pressure ◽  
Platelet Rich Plasma ◽  
Metabolic Activation ◽  
Platelet Factor ◽  
Malondialdehyde Formation ◽  
Shape Changes

SummaryPlatelet rich plasma (PRP) exposed in vitro to 200 mm Hg above atmospheric pressure showed a significant increase in malondialdehyde (MDA) formation compared to PRP at atmospheric pressure. This difference is also evident when platelets are incubated with arachidonic acid.The increase of MDA demonstrates that the increased beta- thromboglobulin and platelet factor 4 in plasma and the shape changes of platelets after pressure stimulation in vitro that were described in a previous paper result from the release reaction.Pressure-induced effects in vivo are discussed

scholarly journals The influence of the moisture content in historical masonry walls on the load bearing capacity

2018 ◽  
Vol 49 ◽  
pp. 00100
Author(s):  
Monika Siewczynska ◽  
Barbara Ksit
Keyword(s):  
Moisture Content ◽  
Bearing Capacity ◽  
Actual State ◽  
Masonry Walls ◽  
Historical Buildings ◽  
Load Bearing Capacity ◽  
Reliable Determination ◽  
Load Bearing ◽  
Historical Masonry

The moisture content in historical masonry walls, particularly on the ground floor, caused by i.e. lack of damp insulation, is a phenomenon of common occurrence. It is usually analysed in terms of mycological changes, thermal insulation and frost damage. The paper discusses the influence of the increased moisture content on the weight and load bearing capacity of the structure. The determination of moisture content in masonry elements, performed during the inspection of the building, provides information from which an increase in the structure's weight can be defined. Reliable tests for the moisture content and compressive strength of masonry and mortar components are invasive, and the number of testing in historical buildings should be limited to the minimum necessary to preserve their vintage nature. As a result, the received overall picture of the work of masonry may not be consistent with its actual state since historical buildings could have been rebuilt or repaired, and consequently, contain masonry conversions made of various materials with different properties. Absorbability can serve here as an example as it is a factor that disrupts a reliable determination of load bearing capacity values of masonry structures. The article attempts to determine the change in load bearing capacity of a moist masonry structure compared to the original - in the air-dry state - for various types of historical masonry and mortar components. The main influence analysed was due to capillary action, whereas the effect of other sources of moisture, i.e. salinity, was excluded.

Collapse State of Multi-Storey Masonry Walls Reinforced by Steel Ties Subjected to In-Plane Horizontal Loads

2017 ◽  
Vol 747 ◽  
pp. 686-693 ◽  
Author(s):  
Mario Como ◽  
Simona Coccia ◽  
Fabio di Carlo
Keyword(s):  
Limit Load ◽  
Masonry Walls ◽  
Masonry Building ◽  
Distribution Constant ◽  
Plane Failure ◽  
Collapse State ◽  
Definition Of ◽  
The Masses ◽  
Regular Patterns

The determination of the seismic strength of masonry building is strictly connected to the in-plane strength of masonry walls under the action of horizontal forces. Simplified criteria are currently available in literature, based on modelling of the structure as loaded by dead loads and by a gradually increasing distribution of horizontal forces, proportional to the mass of the building. According to this approach, called push-over method, the seismic strength of the building corresponds to the intensity of these gradually increasing horizontal loads, leading the building to the failure condition. This paper moves in the framework of the Limit Analysis, based on the Heyman’s masonry model (1966), rigid in compression with no tensile strength. The resistant model refers to a multi-storey wall with openings arranged in regular patterns, along both vertical and horizontal directions, reinforced at floor levels by steel ties. The in-plane failure of the regular multi-storey walls can occur with the development of various kinematically admissible mechanisms, characterized by the attainment of the yielding state in the steel ties. The proposed methodology consists in the definition of the mechanism along which the failure effectively occurs and in a subsequent check of the statical admissibility of the internal stress state at the limit load. Only in this case, the corresponding kinematical multiplier is the effective collapse multiplier. The presence of the panels situated above the openings strongly conditions the in-plane failure of the wall, acting as diagonal struts, causing different horizontal displacements between the piers at the floor levels and consequently engaging the horizontal ties in the mechanism. In order to ensure the development of the global failure, avoiding local brittle failures, steel strengths of the ties have thus to be suitably defined. Finally, a parametric investigation is carried out considering different geometries of masonry walls and varying the position of the piers self-weights and the horizontal forces distribution, constant or proportional to the height of the masses from the foundation level.

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