Seismic Strengthening of Unreinforced Masonry Piers with Steel Elements

1996 ◽  
Vol 12 (4) ◽  
pp. 845-862 ◽  
Author(s):  
Durgesh C. Rai ◽  
Subhash C. Goel
Keyword(s):  
Load Sharing ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Hysteretic Behavior ◽  
Large Displacements ◽  
Seismic Strengthening ◽  
Lateral Resistance ◽  
Steel Framing ◽  
Number Of Cycles

The system of wall piers and spandrels, created by openings, largely controls the inplane lateral resistance of the wall. For the “rocking-critical” masonry wall piers, the overall hysteretic behavior can be significantly improved by installing a steel framing system consisting of vertical and horizontal elements around the wall — without any braces. Vertical elements provide the necessary hold-down forces to stabilize the rocking piers. The stabilized piers “rocked” through a number of cycles of large displacements (up to 2.5%) without crumbling or shattering, displaying a ductile response. The strengthened system has excellent strength, stiffness and ductility, despite the brittleness of the masonry because of considerable load sharing between the existing masonry and the added steel elements. FE analyses predicted the envelope response of the rocking piers accurately. A simple mechanics based model was developed to predict the load-deflection behavior of a stabilized rocking pier which can be used to design the strengthening system more rationally.

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.

Structural window frame for in-plane seismic strengthening of masonry wall buildings

2018 ◽  
Vol 13 (1) ◽  
pp. 98-113 ◽  
Author(s):  
Jorge Miguel Proença ◽  
António S. Gago ◽  
André Vilas Boas
Keyword(s):  
Masonry Wall ◽  
Seismic Strengthening ◽  
Window Frame

Nonlinear Finite Element Analysis of Masonry Wall Strengthened with Steel Strips

2013 ◽  
Vol 838-841 ◽  
pp. 284-296
Author(s):  
Yu Hua Wang ◽  
Bei Bei Wang ◽  
Pei Chi ◽  
Jun Dong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lateral Displacement ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Shear Capacity ◽  
Computational Formula ◽  
Element Analysis ◽  
Steel Strips ◽  
The Cross

The finite element analysis method was adopted to simulate the masonry wall strengthened with steel strips and was verified by comparing with test results. The influence rules of two factors including the cross sectional area of steel strips and vertical compression were investigated. The results show that, as for unreinforced masonry wall, the relationship of the shear capacity of unreinforced masonry wall and the vertical compressive strain is linear under lateral load; the speed of stiffness degeneration is accelerated after the peak point of the curves, but decrease with the increasing of lateral displacement. As for masonry wall strengthened with steel strips, the shear capacity increases significantly, and shows nonlinear relationship with the cross section area of the steel strips and vertical compression; ductility is improved. Finally, a computational formula of shear capacity based on a lot of parametric analysis is proposed to calculate the sectional dimension of steel strips, and it provides theoretical foundation for establishing thorough design method of masonry wall strengthened with steel strips.

A Macromechanical Constitutive Model of Shape Memory Alloys Under Uniaxial Cyclic Loading

2012 ◽  
Vol 28 (3) ◽  
pp. 469-477 ◽  
Author(s):  
H. Lei ◽  
B. Zhou ◽  
Z. Wang ◽  
Y. Wang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Hysteretic Behavior ◽  
Test Results ◽  
Model Match ◽  
Number Of Cycles ◽  
The Relationship

AbstractIn this paper, the thermomechanical behavior of shape memory alloys (SMAs) subjected to uniaxial cyclic loading is investigated. To obtain experimental data, the strain-controlled cyclic loading-unloading tests are conducted at various strain-rates and temperatures. Dislocations slip and deformation twins are considered to be the main reason that causes the unique cyclic mechanical behavior of SMAs. A new variable of shape memory residual factor was introduced, which will tend to zero with the increasing of the number of cycles. Exponential form equations are established to describe the evolution of shape memory residual factor, elastic modulus and critical stress, in which the influence of strain-rate, number of cycles and temperature are taken into account. The relationship between critical stresses and temperature is modified by considering the cycling effect. A macromechanical constitutive model was constructed to predict the cyclic mechanical behavior at constant temperature. Based on the material parameters obtained from test results, the hysteretic behavior of SMAs subjected to isothermal uniaxial cyclic loading is simulated. It is shown that the numerical results of the modified model match well with the test results.

STRENGTHENING METHOD OF UNREINFORCED MASONRY WALLS BY BRACE ELEMENTS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Ariunaa Ganbaatar ◽  
Haruyuki Yamamoto
Keyword(s):  
Yield Criterion ◽  
Pushover Analysis ◽  
Element Model ◽  
Strength Properties ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Interface Element ◽  
Flow Rule ◽  
Dimensional Finite Element ◽  
Tension And Compression

The ductility and strength properties of lightweight steel brace element for structural strengthening of unreinforced masonry (URM) wall is reported in this study. The performance of URM wall without brace and with brace is evaluated by an elastoplastic nonlinear analysis including the yield criterion, flow rule and hardening rule. Masonry constituent is implemented into two-dimensional finite element model developed in Fortran code. The brittle failure of URM wall is analyzed using by an interface element to model bricks and joints. Two types of steel brace elements which can resist only tension and both tension and compression have been considered to increase the ductility of URM wall. The comparison between experimental and numerical results adopted in simplified-micro masonry modeling is illustrated with the relationship between force and displacement. The ductility and strength of masonry wall with the tension and the tension-compression brace element were different results of URM wall by in-plane pushover analysis. As for the simplification for a calculation of masonry wall, equivalent masonry model is discussed and besides diagonal brace elements, the additional vertical brace element is assumed for the high masonry wall by the numerical analysis.

Sign in / Sign up

Export Citation Format

Share Document