scholarly journals Quasi-static cyclic tests of two mixed reinforced concrete–unreinforced masonry wall structures

2014 ◽  
Vol 71 ◽  
pp. 201-211 ◽  
Author(s):  
Alessandro Paparo ◽  
Katrin Beyer
Keyword(s):  
Reinforced Concrete ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Cyclic Tests ◽  
Wall Structures

A proposal for the compatibility of static and dynamic seismic base shear provisions of the National Building Code

1982 ◽  
Vol 9 (2) ◽  
pp. 308-312 ◽  
Author(s):  
W. K. Tso
Keyword(s):  
Reinforced Concrete ◽  
Shear Wall ◽  
Masonry Wall ◽  
Building Code ◽  
Frame Structures ◽  
Base Shear ◽  
Significant Discrepancy ◽  
Moment Resisting Frame ◽  
Wall Structures ◽  
Moment Resisting

A comparison is made, based on static and dynamic base shear calculations according to the National Building Code of Canada of 1980, for four types of simple structures, namely, uniform moment resisting frame structures, uniform ductile flexural wall structures, uniform reinforced concrete shear wall structures, and unreinforced masonry wall structures. It is shown that a significant discrepancy exists between the static and dynamic base shear values, depending on the type and the fundamental period of the structure. The causes for the discrepancy and the necessity to make static and dynamic base shears compatible are discussed.

scholarly journals Numerical Modeling of Unreinforced Masonry Walls Strengthened with Fe-Based Shape Memory Alloy Strips

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2961
Author(s):  
Moein Rezapour ◽  
Mehdi Ghassemieh ◽  
Masoud Motavalli ◽  
Moslem Shahverdi
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Vertical Strip ◽  
Maximum Resistance ◽  
The Cross ◽  
Post Tensioning

This study presents a new way to improve masonry wall behavior. Masonry structures comprise a significant part of the world’s structures. These structures are very vulnerable to earthquakes, and their performances need to be improved. One way to enhance the performances of such types of structures is the use of post-tensioning reinforcements. In the current study, the effects of shape memory alloy as post-tensioning reinforcements on originally unreinforced masonry walls were investigated using finite element simulations in Abaqus. The developed models were validated based on experimental results in the literature. Iron-based shape memory alloy strips were installed on masonry walls by three different configurations, namely in cross or vertical forms. Seven macroscopic masonry walls were modeled in Abaqus software and were subjected to cyclic loading protocol. Parameters such as stiffness, strength, durability, and energy dissipation of these models were then compared. According to the results, the Fe-based strips increased the strength, stiffness, and energy dissipation capacity. So that in the vertical-strip walls, the stiffness increases by 98.1%, and in the cross-strip model's position, the stiffness increases by 127.9%. In the vertical-strip model, the maximum resistance is equal to 108 kN, while in the end cycle, this number is reduced by almost half and reaches 40 kN, in the cross-strip model, the maximum resistance is equal to 104 kN, and in the final cycle, this number decreases by only 13.5% and reaches 90 kN. The scattering of Fe-based strips plays an important role in energy dissipation. Based on the observed behaviors, the greater the scattering, the higher the energy dissipation. The increase was more visible in the walls with the configuration of the crossed Fe-based strips.

Inelastic Analysis of Reinforced Concrete Shear Wall Structures Under Seismic Excitation

1993 ◽  
Author(s):  
Ming L. Wang
Keyword(s):  
Reinforced Concrete ◽  
Response Spectra ◽  
Shear Wall ◽  
Stiffness Degradation ◽  
Structural Stiffness ◽  
Hysteresis Model ◽  
Safety Equipment ◽  
Floor Response Spectra ◽  
Wall Structures ◽  
Degradation Models

Abstract During strong ground motions, members of reinforced concrete structures undergo cyclic deformations and experience permanent damage. Members may lose their initial stiffness as well as strength. Recently, Los Alamos National Laboratory has performed experiments on scale models of shear wall structures subjected to recorded earthquake signals. In general, the results indicated that the measured structural stiffness decreased with increased levels of excitation in the linear response region. Furthermore, a significant reduction in strength as well as in stiffness was also observed in the inelastic range. Since the in-structure floor response spectra, which are used to design and qualify safety equipment, have been based on calculated structural stiffness and frequencies, it is possible that certain safety equipment could experience greater seismic loads than specified for qualification due to stiffness reduction. In this research, a hysteresis model based on the concept of accumulated damage has been developed to account for this stiffness degradation both in the linear and inelastic ranges. Single and three degrees of freedom seismic Category I structures were analyzed and compared with equivalent linear stiffness degradation models in terms of maximum displacement responses, permanent displacement, and floor response spectra. The results indicate significant differences in responses between the hysteresis model and equivalent linear stiffness degradation models. The hysteresis model is recommended in the analysis of reinforced concrete shear-wall structures to obtain the in-structure floor response spectra for equipment qualification. Results of both cumulative and one shot tests are compared.

The effect of vertical near-field ground motions on the collapse risk of high-rise reinforced concrete frame-core wall structures

2021 ◽  
pp. 136943322110561
Author(s):  
Arsam Taslimi ◽  
Mohsen Tehranizadeh
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Fragility Curves ◽  
Ground Motions ◽  
Reinforced Concrete Frame ◽  
Engineering Structures ◽  
Intensity Measures ◽  
Vertical Excitation ◽  
High Rise ◽  
Wall Structures

According to the observations of past earthquakes, the vertical ground motions have had a striking influence on the engineering structures, especially reinforced concrete ones. Nevertheless, the number of studies on their aftermath is insufficient, and despite some endeavors done by researchers, there is still a shortage of knowledge about the inclusion of vertical excitation on the seismic performance and the collapse probability of RC buildings. Hence, the variation in the collapse risk of three high-rise RC frame-core wall structures when they undergo bi-directional ground motions is discussed. In this paper, incremental dynamic analyses are carried out under two circumstances, including the horizontal (H) and the combined horizontal and vertical (H+V) earthquakes, and the seismic fragility curves are derived. The inter-story drift ratio corresponding to the onset of collapse has also been defined. The buildings collapse risk under the two circumstances is obtained from the risk integral. Results indicate that in the H+V state, structures meet the collapse criteria for lower intensity measures. Thus, the collapse risk increases as the structures are subjected to bi-directional seismic loads, and the consideration of this effect leads to a more accurate evaluation of buildings seismic performance.

Sign in / Sign up

Export Citation Format

Share Document