scholarly journals Some of the Latest Active Strengthening Techniques for Masonry Buildings: A Critical Analysis

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1151 ◽  
Author(s):  
Elena Ferretti ◽  
Giovanni Pascale
Keyword(s):  
Stress Field ◽  
Static Analysis ◽  
Dynamic Load ◽  
Critical Analysis ◽  
Masonry Buildings ◽  
Load Bearing Capacity ◽  
Plane Shear ◽  
Out Of Plane ◽  
Active Confinement ◽  
Static Conditions

The present paper deals with the retrofitting of unreinforced masonry (URM) buildings, subjected to in-plane shear and out of-plane loading when struck by an earthquake. After an introductive comparison between some of the latest punctual and continuous active retrofitting methods, the authors focused on the two most effective active continuous techniques, the CAM (Active Confinement of Masonry) system and the Φ system, which also improve the box-type behavior of buildings. These two retrofitting systems allow increasing both the static and dynamic load-bearing capacity of masonry buildings. Nevertheless, information on how they actually modify the stress field in static conditions is lacking and sometimes questionable in the literature. Therefore, the authors performed a static analysis in the plane of Mohr/Coulomb, with the dual intent to clarify which of the two is preferable under static conditions and whether the models currently used to design the retrofitting systems are fully adequate.

scholarly journals Some of the Latest Active Strengthening Techniques for Masonry Buildings: A Critical Analysis

2019 ◽  
Author(s):  
Elena Ferretti ◽  
Giovanni Pascale
Keyword(s):  
Stress Field ◽  
Bearing Capacity ◽  
Static Analysis ◽  
Dynamic Load ◽  
Critical Analysis ◽  
Masonry Buildings ◽  
Load Bearing Capacity ◽  
Plane Shear ◽  
Out Of Plane ◽  
Static Conditions

The present paper deals with the retrofitting of unreinforced masonry (URM) buildings, subjected to in-plane shear and out of-plane loading when struck by an earthquake. After an introductive comparison between some of the latest punctual and continuous active retrofitting methods, the authors focused on the two most effective active continuous techniques, the CAM system and the Φ system, which also improve the box-type behavior of buildings. These two retrofitting systems allow us to increase both the static and dynamic load-bearing capacity of masonry buildings. Nevertheless, information on how they actually modify the stress field in static conditions is lacking and sometimes questionable, in the literature. Therefore, we performed a static analysis in the plane of Mohr/Coulomb, with the dual intent to clarify which of the two is preferable under static conditions and whether the models currently used to design the retrofitting systems are fully adequate.

The Whittier Narrows, California Earthquake of October 1, 1987—Preliminary Evaluation of the Performance of Strengthened Unreinforced Masonry Buildings

1988 ◽  
Vol 4 (1) ◽  
pp. 197-212 ◽  
Author(s):  
T. A. Moore ◽  
J. H. Kobzeff ◽  
J. Diri ◽  
C. Arnold
Keyword(s):  
Los Angeles ◽  
Case Studies ◽  
Unreinforced Masonry ◽  
Preliminary Evaluation ◽  
Masonry Buildings ◽  
Plane Shear ◽  
Hazard Reduction ◽  
Out Of Plane ◽  
Shear Failures ◽  
Bending Failure

This report presents preliminary case studies of the performance of selected unreinforced masonry buildings during the Whittier Narrows Earthquakes. Attention is focused on buildings located in the downtown Los Angeles area which have been rehabilitated to conform with the Los Angeles hazard reduction Ordinance. There was no life loss or major injuries attributed to the response of unreinforced masonry buildings to the earthquakes. However, there was a significant number of both rehabilitated and non-strengthened buildings for which masonry peeled off upper story walls. This was mainly due to separation of the outer whythe of brick, or out-of-plane bending failure, and/or in-plane shear failures of wall piers, particularly at building corners. The falling bricks associated with these failures did present an injury hazard so it is important to investigate economical measures to minimize these hazards in future earthquakes.

scholarly journals Effectiveness of Active Confinement Techniques with Steel Ribbons: Masonry Buildings

2018 ◽  
Vol 2 (3) ◽  
pp. 17-29 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Stainless Steel ◽  
Static Analysis ◽  
Strengthening Mechanism ◽  
Masonry Buildings ◽  
Seismic Codes ◽  
Future Developments ◽  
Critical Issues ◽  
Weak Points ◽  
Active Confinement

Abstract In the present paper, we analyzed the main advantages of the active confinement techniques with a particular focus on the CAM system, which is an Italian reinforcement technique with pre-tensioned stainless steel ribbons. Italian seismic codes classify the CAM system as belonging to the strengthening category of “horizontal and vertical ties”. Therefore, we compared the CAM system to the reinforcement techniques with horizontal and vertical ties in order to understand the actual similarities and possible differences between them. Moreover, we offered a deep analysis of the main critical issues of the CAM system, distinguishing between geometrical and mechanical weak-points. In particular, we analyzed the strengthening mechanism of the CAM system, still poorly understood, by performing a static analysis in the Mohr/Coulomb plane. Finally, we provided suggestions for future developments.

scholarly journals A Review of the Methods for Predicting the Effective In-Plane Shear Modulus of Cross-Laminated Timber (CLT)

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Mehsam Tanzim Khan ◽  
Ying Hei Chui ◽  
Dongsheng Huang
Keyword(s):  
Shear Modulus ◽  
Structural Members ◽  
Current Standard ◽  
Load Bearing Capacity ◽  
Plane Shear ◽  
Cross Laminated Timber ◽  
High Rise ◽  
Out Of Plane ◽  
Alternative Material ◽  
Almost All

Cross-laminated timber (CLT) is a type of engineered wood product that offers both high in-plane and out-of-plane load-bearing capacity. It is slowly becoming an alternative material for building high-rise structures. However, there is no current standard or regulation for determining the shear modulus of CLT under in-plane loading condition, which is a very important property for its use as structural members. Few methods have been proposed over the last decade to determine the in-plane shear modulus of CLT. Almost all of the methods proposed until now have their strengths and weaknesses. In this paper, some of the prominent methods for determining the in-plane shear modulus of CLT are described and analysed. The descriptions along with the critical discussions will facilitate a better understanding and might pave the way to further enhancements of the method(s) to determine the in-plane shear modulus of CLT.

scholarly journals Effectiveness of Active Confinement Techniques with Steel Ribbons: Masonry Buildings

2018 ◽  
Vol 2 (3) ◽  
pp. 18 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Stainless Steel ◽  
Static Analysis ◽  
Strengthening Mechanism ◽  
Masonry Buildings ◽  
Seismic Codes ◽  
Future Developments ◽  
Critical Issues ◽  
Weak Points ◽  
Active Confinement

In the present paper, we analyzed the main advantages of the active confinement techniques with a particular focus on the CAM system, which is an Italian reinforcement technique with pre-tensioned stainless steel ribbons. Italian seismic codes classify the CAM system as belonging to the strengthening category of “horizontal and vertical ties”. Therefore, we compared the CAM system to the reinforcement techniques with horizontal and vertical ties in order to understand the actual similarities and possible differences between them. Moreover, we offered a deep analysis of the main critical issues of the CAM system, distinguishing between geometrical and mechanical weak-points. In particular, we analyzed the strengthening mechanism of the CAM system, still poorly understood, by performing a static analysis in the Mohr/Coulomb plane. Finally, we provided suggestions for future developments.

Out-of-plane shear and out-of plane Young’s modulus of double-layer graphene

2013 ◽  
Vol 564 ◽  
pp. 37-40 ◽  
Author(s):  
Balázs Hajgató ◽  
Songül Güryel ◽  
Yves Dauphin ◽  
Jean-Marie Blairon ◽  
Hans E. Miltner ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Double Layer ◽  
Young's Modulus ◽  
Plane Shear ◽  
Layer Graphene ◽  
Out Of Plane

scholarly journals Damage during the 6–24 February 2017 Ayvacık (Çanakkale) earthquake swarm

2018 ◽  
Vol 18 (3) ◽  
pp. 921-934 ◽  
Author(s):  
Ramazan Livaoğlu ◽  
Mehmet Ömer Timurağaoğlu ◽  
Cavit Serhatoğlu ◽  
Mahmud Sami Döven
Keyword(s):  
Earthquake Swarm ◽  
Structural Features ◽  
Load Bearing Capacity ◽  
Distribution Maps ◽  
Mortar Strength ◽  
Development Level ◽  
Out Of Plane ◽  
Connection Type ◽  
Past Experiences ◽  
Construction Practice

Abstract. On 6 February 2017 an earthquake swarm began at the western end of Turkey. This was the first recorded swarm in the Çanakkale region since continuous seismic monitoring began in 1970. The number of earthquakes located increased during the following 10 days. This paper describes the output of a survey carried out in the earthquake-prone towns in the area of Ayvacık, Çanakkale, Turkey, in February 2017 after the earthquakes. Observations of traditional buildings were made on site at the rural area of Ayvacık. A description of the main structural features and their effects on the most frequently viewed damage modes were made according to in-plane, out-of-plane behavior of the wall regarding construction practice, connection type, etc. It was found that there were no convenient connections like cavity ties or sufficient mortar strength resulting in decreased and/or lack of lateral load bearing capacity of the wall. Furthermore, distribution maps of damaged/undamaged buildings according to villages, damage ratios, structures and damage levels are generated. Distribution maps showed that damage ratio of structures is higher in villages close to epicenter and decrease away from epicenter except Gülpınar, where past experiences and development level affect the construction quality.

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