Parametric study of multi-story, perforated, partially grouted masonry walls subjected to in-plane cyclic actions

2020 ◽  
Author(s):  
Klaus Medeiros ◽  
Kyle Chavez ◽  
Fernando S. Fonseca ◽  
Guilherme Parsekian ◽  
Nigel G. Shrive
Keyword(s):  
Experimental Data ◽  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Axial Stress ◽  
Reinforcement Ratio ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Initial Stiffness ◽  
Vertical Reinforcement

Finite element models were developed to assess the influence of several parameters on the load capacity, deflection, and initial stiffness of multi-story, partially grouted masonry walls with openings. The base model was validated with experimental data from three walls. The analyses indicated that the load capacity of masonry walls was considerably sensitive to the ungrouted and grouted masonry strengths and mortar shear strength; moderately sensitive to the vertical reinforcement ratio and aspect ratio; slightly sensitive to the axial stress; and almost insensitive to the opening size, reinforcement spacing, and horizontal reinforcement ratio. The deflection of the walls had well-defined correlations with the masonry strength, vertical reinforcement, axial stress and aspect ratio. The initial stiffness was especially sensitive to the axial stress and the aspect ratio, but weakly correlated with the opening size, and the spacing and size of the reinforcement.

scholarly journals Behavior of Partially Grouted Concrete Masonry Walls under Quasi-Static Cyclic Lateral Loading

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2424
Author(s):  
Sebastián Calderón ◽  
Laura Vargas ◽  
Cristián Sandoval ◽  
Gerardo Araya-Letelier
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Masonry Walls ◽  
Lateral Stiffness ◽  
Edge Elements ◽  
Vertical Reinforcement ◽  
Concrete Masonry ◽  
Resistance Degradation ◽  
Concrete Masonry Walls

Eight partially grouted (PG-RM) concrete masonry walls were tested to study the influence of the strength and width of blocks, the wall aspect ratio, the horizontal and vertical reinforcement ratio, and the presence of edge elements (flanges). The results were analyzed in terms of the failure mode, damage progression, shear strength, lateral stiffness degradation, equivalent viscous damping ratio, and displacement ductility. Additionally, the performances of some existing shear expressions were analyzed by comparing the measured and predicted lateral load capacity of the tested walls. Based on the results, a slight increment in the lateral stiffness was achieved when employing stronger blocks, while the shear strength remained constant. Besides, increasing the width of concrete blocks did not have a significant effect on the shear strength nor in the initial tangential stiffness, but it generated a softer post-peak strength degradation. Increasing the wall aspect ratio reduced the brittleness of the response and the shear strength. Reducing the amount of vertical reinforcement lowered the resulting shear strength, although it also slowed down the post-peak resistance degradation. Transversal edge elements provided integrity to the wall response, generated softer resistance degradation, and improved the symmetry of the response, but they did not raise the lateral resistance.

Out-Of-Plane Behavior of Confined Masonry Walls Subjected to Concentrated Loads (One-Way Bending)

2016 ◽  
Vol 32 (4) ◽  
pp. 2317-2335 ◽  
Author(s):  
Dante Navarrete-Macias ◽  
Jorge Varela-Rivera ◽  
Luis Fernandez-Baqueiro
Keyword(s):  
Aspect Ratio ◽  
Seismic Behavior ◽  
Axial Stress ◽  
Experimental Results ◽  
Masonry Walls ◽  
Cyclic Loads ◽  
Wall Panel ◽  
Confined Masonry ◽  
Plastic Analysis ◽  
Out Of Plane

This paper presents the results of a study on the out-of-plane seismic behavior of confined masonry walls. Five confined walls were tested under reverse cyclic loads. The variables studied were the axial stress and the wall aspect ratio. Analytical out-of-plane strength of walls was calculated considering the strengths of the wall panel and the concrete confining elements. The former was determined using the unidirectional strut method and the latter using a plastic analysis. It was observed that for walls with the same aspect ratio, as the axial stress increases, the out-of-plane strength increases. For walls with the same axial stress, as the aspect ratio increases, the strength decreases. Based on comparisons between analytical and experimental results, it was concluded that the models developed in this work predict accurately the out-of-plane strength of the walls.

Experimental Study on Shear Behavior of Hybrid Fiber Reinforced High Performance Concrete Deep Beams

2012 ◽  
Vol 166-169 ◽  
pp. 664-669
Author(s):  
Sheng Bing Liu ◽  
Lihua Xu
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Polypropylene Fiber ◽  
Shear Behavior ◽  
Calculation Formula ◽  
Hybrid Fiber ◽  
Deep Beams ◽  
Vertical Reinforcement

In order to investigate the effect of steel fiber and polypropylene fiber on shear behavior of HPC deep beams, the shear tests were conducted on 18 different groups of deep beams with steel fiber and polypropylene fiber and 2 groups of HPC deep beams without fiber according to the orthogonal experiment. 6 factors, including the shape of steel fiber, the volume fraction of steel fiber, the aspect ratio of steel fiber, the volume fraction of polypropylene fiber, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement, were compared by direct-viewing analysis. Results illuminate that hybrid fibers greatly increase the diagonal cracking strength and shear strength of HPC deep beams. The aspect ratio of steel fiber plays the most important role in diagonal cracking strength whereas the ratio of web vertical reinforcement has minimum effect. Meanwhile the ratio of web horizontal reinforcement plays the most important role in shear strength whereas the volume fraction of polypropylene fiber has minimum effect. An anti-cracking capacity for inclined section calculation formula and a shear bearing capacity calculation formula for hybrid fiber reinforced HPC deep beams are put forward based on current code. Meantime test verification is carried out and the calculated results are satisfied.

An Experimental Study of Confined Masonry Walls with Varying Aspect Ratios

2015 ◽  
Vol 31 (2) ◽  
pp. 945-968 ◽  
Author(s):  
J. J. Perez Gavilan ◽  
L. E. Flores ◽  
S. M. Alcocer
Keyword(s):  
Aspect Ratio ◽  
Good Accuracy ◽  
Axial Stress ◽  
Masonry Walls ◽  
Inelastic Behavior ◽  
Ductility Demand ◽  
Confined Masonry ◽  
Aspect Ratios ◽  
Wide Range ◽  
Good Agreement

Results from an experimental series of seven full-scale confined masonry walls with height-to-length aspect ratios ( H/L) from 0.3 up to 2.2 are summarized. Results show that neither the level of axial stress nor the aspect ratio had a significant effect on lateral stiffness. Inelastic behavior of the walls, characterized by normalized stiffness degradation with ductility demand, can be estimated with good accuracy with a bilinear function for a ductility demand up to 4.5. A substantial increase in normalized shear strength was observed for walls with decreasing aspect ratio. A correction factor to the nominal cracking strength was deduced based on differences of the flexural deformations for squat and square walls. The factor was then compared to the experimental normalized strength with good agreement. A new expression for inclined cracking shear that can be used for a wide range of wall aspect ratios is proposed.

Detailed micro-modeling of partially grouted reinforced masonry shear walls: extended validation and parametric study

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Sebastián Calderón ◽  
Cristián Sandoval ◽  
Gabriele Milani ◽  
Oriol Arnau
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Parametric Study ◽  
Shear Walls ◽  
Lateral Force ◽  
Reinforcement Ratio ◽  
Design Parameters ◽  
Compression Stress ◽  
Reinforced Masonry ◽  
Micro Modeling

AbstractPartially grouted reinforced masonry (PG-RM) shear walls have been widely used as structural elements in low- and medium-rise earthquake-resistant buildings. Nonetheless, assessing its shear strength represents a complex task mainly because the partial grouting provides a non-constant cross section, which results in heterogeneous stress–strain patterns. Consequently, refined modeling techniques are needed to reproduce local failure mechanisms taking place in these walls, which significantly influence the global response. In response to this issue, a detailed micro-modeling approach based on the finite element method was proposed in previous studies by the authors. Although the numerical strategy provided accurate results, further validation is required. Therefore, in this study, the experimental results of seven PG-RM shear walls of multi-perforated clay bricks with bed-joint reinforcement are employed as validation cases. These seven walls presented variations in five design parameters. The validated numerical model was then employed to perform a parametric study to assess the influence of the wall aspect ratio, axial pre-compression stress, and horizontal reinforcement ratio on the in-plane lateral behavior of PG-RM shear walls. The obtained results show that the three studied design parameters modified the crack patterns of the walls. Besides, increasing the axial pre-compression stress or reducing the aspect ratio resulted in higher walls’ shear strength. Additionally, decreasing the horizontal reinforcement ratio or increasing the aspect ratio generated a higher story-drift ratio at maximum lateral force. Finally, it was corroborated that the positive effect of the axial pre-compression stress on the walls’ shear strength decreases inversely proportional to the aspect ratio.

scholarly journals Application of Artificial Intelligence Methods to Estimate Shear Strength of Reinforced Concrete Shear Wall

2020 ◽  
Author(s):  
Hosein Naderpour ◽  
Mohammadreza Sharei ◽  
Pouyan Fakharian
Keyword(s):  
Neural Network ◽  
Artificial Intelligence ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Shear Walls ◽  
Shear Wall ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Vertical Reinforcement

Shear walls are the type of structural systems that provide the lateral resistance to a building or structure. Lateral loads are applied on one plate and along the vertical dimension of the wall. These type of loads are usually transmitted to the wall collectors. Concrete shear walls have a considerable resistance to lateral seismic loading. Model prediction is required for the shear capacity of these walls to ensure the seismic security of the building. Therefore, a model is proposed to estimate the shear strength of concrete walls using an artificial intelligence algorithm. The input parameters of the neural network include the thickness of the reinforced concrete shear wall, the wall length, the vertical reinforcement ratio, the transverse reinforcement ratio, the compressive strength of the concrete, the stresses of the transverse reinforcement, the stresses of the vertical reinforcement, the ratio of the dimensions. The target parameter is the shear strength of the reinforced concrete shear wall. A total of 58 laboratory data was collected on concrete shear walls. The results of the research show that optimum artificial neural network with a specific number of hidden neurons can accurately estimate the shear capacity of reinforced concrete shear walls. The results indicate that the highest percentage of effect and the lowest percentage of effect have a target function. Additionally, the error rate obtained for predicting shear capacity is 7%, which is an acceptable error in this regard.

Evaluation of Rocking and Toe Crushing Failure of Unreinforced Masonry Walls

2008 ◽  
Vol 11 (5) ◽  
pp. 475-489 ◽  
Author(s):  
Jung-Han Lee ◽  
Chenghao Li ◽  
Sang-Hoon Oh ◽  
Won-Jik Yang ◽  
Waon-Ho Yi
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Failure Modes ◽  
Axial Stress ◽  
Unreinforced Masonry ◽  
Cross Sectional ◽  
Crushing Strength ◽  
Actual Strength ◽  
Relationship Of ◽  
The Relationship

The objectives of this study are to evaluate the variables that affect the shear behavior of unreinforced masonry (URM) walls and to propose the equation of the rocking and toe crushing strength of URM walls by regression analysis using the test data including the previous research. The main variables are the axial stress, the aspect ratio and the thickness of URM walls. The test results show that the specimens are governed by rocking and toe crushing failure modes. The relationship of the shear strength is proportionate to the square root of the vertical axial stress, and the relationship of the shear stress and aspect ratio is linearly proportional. Shear strength and cross sectional area are not proportional. For the URM walls tested, the proposed rocking and toe crushing strength/actual strength ratio of 0.95, and coefficient of correlation R of 0.9889 are more appropriate than the FEMA 306 rocking and toe crushing strength formulas.

scholarly journals In-plane shear strength and damage fragility functions for partially-grouted reinforced masonry walls with bond-beam reinforcement

2021 ◽  
Vol 242 ◽  
pp. 112569
Author(s):  
Zhiming Zhang ◽  
Juan Murcia-Delso ◽  
Cristián Sandoval ◽  
Gerardo Araya-Letelier ◽  
Fenglai Wang
Keyword(s):  
Shear Strength ◽  
Masonry Walls ◽  
Fragility Functions ◽  
Plane Shear ◽  
Reinforced Masonry

scholarly journals Out-of-plane local mechanism analysis with finite element method

2021 ◽  
Vol 8 (1) ◽  
pp. 130-136
Author(s):  
Roberto Spagnuolo
Keyword(s):  
Finite Element ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Mechanism Analysis ◽  
Fem Method ◽  
Local Mechanism ◽  
Out Of Plane ◽  
Smeared Crack ◽  
The Stability ◽  
No Tension Material

Abstract The stability check of masonry structures is a debated problem in Italy that poses serious problems for its extensive use. Indeed, the danger of out of plane collapse of masonry walls, which is one of the more challenging to evaluate, is traditionally addressed not using finite element models (FEM). The power of FEM is not properly used and some simplified method are preferred. In this paper the use of the thrust surface is suggested. This concept allows to to evaluate the eccentricity of the membrane stresses using the FEM method. For this purpose a sophisticated, layered, finite element with a no-tension material is used. To model a no-tension material we used the smeared crack method as it is not mesh-dependent and it is well known since the early ’80 in an ASCE Report [1]. The described element has been implemented by the author in the program Nòlian by Softing.

scholarly journals Impact of Reinforcement Ratio on Shear Behavior of I-Shaped UHPC Beams with and without Fiber Shear Reinforcement

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1525 ◽  
Author(s):  
Altug Yavas ◽  
Cumali Ogun Goker
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
High Performance Concrete ◽  
Shear Behavior ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Ultimate Shear Strength ◽  
Loading Test

In the presented paper, the impacts of steel fiber use and tensile reinforcement ratio on shear behavior of Ultra-High Performance Concrete (UHPC) beams were investigated from the point of different tensile reinforcement ratios. In the scope of the experimental program, a total of eight beams consisting of four reinforcement ratios representing low to high ratios ranged from 0.8% to 2.2% were casted without shear reinforcement and subjected to the four-point loading test. While half of the test beams included 30 mm end-hooked steel fibers (SF-UHPC) with 2.0 vol%, the remaining beams were produced without the fiber to show possible effectiveness of the fiber use. The shear performances were discussed in terms of the load—deflection response, cracking pattern and failure mode, first cracking load and ultimate shear strength. In this sense, all the non-fiber beams were failed by shear with a dramatic load drop, regardless of the tensile reinforcement amount, before the yielding of reinforcement and they produced no deflection capability. The test results showed that while the inclusion of steel fibers to the UHPC mixture with low reinforcement ratios changed the failure mode from the shear to flexure, it significantly enhanced the ultimate shear strength in the case of higher reinforcement ratio through the SF-UHPC’ superior mechanical properties and fibers’ crack-bridging ability.

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