scholarly journals Polypropylene as a Retrofitting Material for Shear Walls

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2503
Author(s):  
Enea Mustafaraj ◽  
Yavuz Yardim ◽  
Marco Corradi ◽  
Antonio Borri
Keyword(s):  
Load Capacity ◽  
Shear Walls ◽  
Experimental Program ◽  
Test Results ◽  
Short Fibers ◽  
Epoxy Adhesives ◽  
Load Carrying ◽  
Energy Dissipation Capacity ◽  
Long Term Behavior

In recent years, on account of their excellent mechanical properties, composite materials (made of epoxy-bonded carbon, glass, or aramid fibers) have been used to reinforce masonry walls against in-plane actions. These materials have proven to be an effective solution for the strengthening of unreinforced masonry (URM) walls. Lately, research has shifted to the study of different types of fibers to avoid the use of epoxy adhesives, whose long-term behavior and compatibility with masonry are poor. This paper describes an experimental program that investigated the behavior of URM shear walls strengthened with two types of commercially available polypropylene products: short fibers (fiber length = 12 mm) and polypropylene nets. This investigation aimed to evaluate the influence of polypropylene reinforcement, embedded into an inorganic matrix, in terms of the improvement of the lateral load-carrying capacity, failure mechanism, ductility, and energy dissipation capacity of URM wall panels, where nine walls were subjected to in-plane loads using a racking test setup. The study showed that using two layers of polypropylene fibers embedded into a cementitious matrix greatly increased the in-plane load capacity of the brickwork masonry. On the other hand, the test results indicated that polypropylene nets, used as a repair method for cracked shear walls, cannot improve the structural performance of the walls.

Estimation of Seismic Energy Dissipation for Steel Slit Shear Walls Considering Out-of-Plane Buckling

2021 ◽  
Author(s):  
Yiming Ma ◽  
Liusheng He ◽  
Ming Li
Keyword(s):  
Energy Dissipation ◽  
Shear Walls ◽  
Seismic Energy ◽  
Thickness Ratio ◽  
Design Parameters ◽  
Test Results ◽  
Loading Test ◽  
Aspect Ratios ◽  
Out Of Plane ◽  
Energy Dissipation Capacity

Steel slit shear walls (SSSWs), made by cutting slits in steel plates, are increasingly adopted in seismic design of buildings for energy dissipation. This paper estimates the seismic energy dissipation capacity of SSSWs considering out-of-plane buckling. In the experimental study, three SSSW specimens were designed with different width-thickness ratios and aspect ratios and tested under quasi-static cyclic loading. Test results showed that the width-thickness ratio of the links dominated the occurrence of out-of-plane buckling, which produced pinching in the hysteresis and thus reduced the energy dissipation capacity. Out-of-plane buckling occurred earlier for the links with a larger width-thickness ratio, and vice versa. Refined finite element model was built for the SSSW specimens, and validated by the test results. The concept of average pinching parameter was proposed to quantify the degree of pinching in the hysteresis. Through the parametric analysis, an equation was derived to estimate the average pinching parameter of the SSSWs with different design parameters. A new method for estimating the energy dissipation of the SSSWs considering out-of-plane buckling was proposed, by which the predicted energy dissipation agreed well with the test results.

scholarly journals The Assessment of Using CFRP to Enhance the Behavior of High Strength Reinforced Concrete Corbels

2021 ◽  
Vol 28 (1) ◽  
pp. 71-83
Author(s):  
Mazin Abdulrahman ◽  
Shakir Salih ◽  
Rusul Abduljabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Strength ◽  
Load Capacity ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Ultimate Load Capacity ◽  
Load Carrying ◽  
Externally Bonded ◽  
Effective Depth

In this research, an experimental study is conducted to investigate the behavior and strength of high strength reinforced concrete corbels externally bonded with CFRP fabric sheets and Plates with different patterns taking into account the effect of adopted variables in enhancing the ultimate strength; the effect of shear span to effective depth (a/d), configuration, type and amount of bonding. Eleven high strength reinforced corbels were cast and tested under vertical loads. Test results showed there was an improvement in the behavior and load carrying capacity of all strengthened corbels. An increasing in the ultimate strength of strengthened corbel by inclined CFRP strips reached to (92.1%) while the increasing reached to (84.21%) for using one horizontal CFRP Plates compared to un-strengthened reference specimen. Also, it can be conducted that the increase of (a/d) ratio from (0.6 to 0.8) resulted in decreasing by 21.05% in ultimate load capacity of corbels and from (0.4 to 0.6) by 31.25% and 58.69% in cracking and ultimate loads respectively Using CFRP .

Time-dependent displacement behaviour of model adfreeze and grouted piles in saline frozen soils

1994 ◽  
Vol 31 (3) ◽  
pp. 395-406 ◽  
Author(s):  
K.W. Biggar ◽  
D.C. Sego
Keyword(s):  
Field Studies ◽  
Frozen Soil ◽  
Silty Sand ◽  
Time Dependent ◽  
Test Results ◽  
Model Pile ◽  
Laboratory Test Results ◽  
Load Carrying ◽  
Pile Deformation

The findings of a laboratory study on the time-dependent displacement of model piles in saline frozen soil are reported. The short-term time-dependent pile deformation in ice-poor saline silty sand was best described using a simple power law of time, whereas the long-term time-dependent deformations were best described using a flow law formulation similar to that used to describe the long-term time-dependent deformation of ice or ice-rich permafrost. The use of cementitious grout as a backfill resulted in doubling of the pile load carrying capacity for a given displacement rate. The laboratory test results compare well with other laboratory and field studies. Key words : frozen soil, saline, model pile, time-dependent deformation, sand backfill, grout.

BEHAVIOR OF EXPANSIVE CONCRETE-FILLED STEEL TUBULAR COLUMNS UNDER AXIAL LOADINGS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Aman Mwafy ◽  
Ame El-Dieb ◽  
Abdulaziz Lazkani
Keyword(s):  
Load Capacity ◽  
Steel Tube ◽  
Experimental Program ◽  
Outer Diameter ◽  
Test Results ◽  
Limited Information ◽  
Tubular Columns ◽  
Expansive Concrete ◽  
Axial Load Capacity ◽  
Concrete Filled Steel Tubes

Concrete-filled steel tubes (CFSTs) have been introduced to expedite construction and increase the confinement of concrete by the steel tube. While changing the confinement level through the use of expansive additives (EAs) will have an impact on the performance of CFSTs, limited information is available on the behavior of expansive concrete-filled steel tubular (ECFST) columns. The objective of this study is thus twofold: (i) to experimentally assess the behavior of axially loaded ECFSTs, and (ii) to investigate the correlation between the test results and those obtained from prediction approaches. The experimental program of this study consists of testing four 1500 mm CFST/ECFST columns with 153.6 mm outer diameter and 3 mm thickness. The ECFST specimens are divided into two subgroups with 0% and 12% EA dosage and two concrete mixtures, 16 and 37 MPa. The results indicate that the latter is the most promising mixture since it results in a significant enhancement of 64% in the axial load capacity of ECFST columns compare with CFSTs. The study also recommends employing specific confined concrete models with the existing code prediction approaches to arrive at the best correlation with test results.

Long-Term Behavior of Low-Heat Cement Concrete under Different Curing Temperatures

2016 ◽  
Vol 723 ◽  
pp. 819-823 ◽  
Author(s):  
Jae Sung Mun ◽  
Keun Hyeok Yang ◽  
Si Jun Kim
Keyword(s):  
Drying Shrinkage ◽  
Curing Temperature ◽  
Limestone Powder ◽  
Partial Replacement ◽  
Mass Concrete ◽  
Test Results ◽  
Long Term Behavior ◽  
Ambient Curing ◽  
Ternary Blended Concrete

The present study is to estimate long-term characteristics of low-heat cement-based ternary blended concrete prepared for reducing hydration heat in mass concrete. 15% modified fly ash and 5% limestone powder were added for partial replacement of the low-heat cement. To achieve the designed compressive strength of 42 MPa, water-to-binder ratios were determined to be 27.5, 30 and 32.5% for ambient curing temperatures of 5, 20 and 40°C, respectively. Test results showed that, with the decrease in curing temperature, the drying shrinkage strains tended to decrease, whereas creep strain increased.

Effect of interface gap on load–slip characteristics of timber joints fabricated with multiple nails

1985 ◽  
Vol 12 (1) ◽  
pp. 104-113 ◽  
Author(s):  
S. K. Malhotra ◽  
B. Thomas
Keyword(s):  
Structural Engineering ◽  
Load Capacity ◽  
Lateral Load ◽  
Experimental Program ◽  
Load Carrying Capacity ◽  
Timber Construction ◽  
Interface Characteristics ◽  
Load Carrying ◽  
Friction Joint ◽  
Timber Joints

An experimental program, exploratory in nature, has been carried out to investigate the effect of interface gap on the load–slip behaviour of joints fabricated with multiple nails. In total, 320 joint specimens have been tested. Modification factors are developed to account for the effects of number of nails and interface gap on the overall load-carrying capacity of joints with multiple nails. The current practice for the design of nailed joints is that a joint fastened together with multiple nails in a row, regardless of the interface characteristics of that joint, carries lateral load equal to the product of the lateral-load capacity of the corresponding joint with a single nail and the number of nails in a row of the joint. The findings of this investigation indicate this practice to be somewhat of an overestimation of the overall capacity of the joint. Key words: design, interface gap, interface friction, joint slip, loads (forces), modification factors, multiple fasteners, nailed joints, stiffness, structural engineering, tests, timber construction.

Vertical load-carrying behavior and design models for micropiles considering foundation configuration conditions

2017 ◽  
Vol 54 (2) ◽  
pp. 234-247 ◽  
Author(s):  
Doohyun Kyung ◽  
Daehong Kim ◽  
Garam Kim ◽  
Junhwan Lee
Keyword(s):  
Ultimate Load ◽  
Load Capacity ◽  
Initial Increase ◽  
Vertical Load ◽  
Test Results ◽  
Ultimate Load Capacity ◽  
Case Examples ◽  
Installation Angle ◽  
Load Carrying ◽  
Load Tests

In the present study, the vertical load-carrying behavior of micropile foundations with various configuration conditions was investigated based on results from model load tests. Considered configuration conditions included micropile inclination angle, spacing of micropiles, and types of micropile foundations. The ultimate load capacity of micropiles varied with installation angle, showing an initial increase and peak followed by a gradual decrease with further increase in installation angle. The ultimate load capacity of micropiled rafts was affected by both installation angle and micropile spacing. The load-carrying mechanism of micropiles for the inclined condition was proposed based on the decomposed axial and lateral load and resistance components. Using the proposed load-carrying mechanism and test results obtained in this study, the load capacity ratio for an inclined micropile was proposed. The group effect and interaction effect factors for group micropiles and micropiled rafts were proposed, respectively, all of which can be used to estimate the load-carrying capacity of micropile foundations. Field load tests were conducted and it was seen that estimated results using the proposed method were in good agreement with measured results. Additional comparison with case examples from the literature also confirmed the validity of the proposed method.

scholarly journals Repairing of Reactive Powder Concrete T-Beams Containing Web Opening by CFRP Strips

2019 ◽  
Vol 26 (1) ◽  
pp. 9-19
Author(s):  
Mazin B. Abdulrahman ◽  
Husham M. Rashid
Keyword(s):  
Carrying Capacity ◽  
Ultimate Load ◽  
Experimental Program ◽  
Reactive Powder Concrete ◽  
Shape Effect ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Load Carrying ◽  
Ultimate Load Carrying Capacity ◽  
Reactive Powder

In modern buildings, transverse openings are often used beams for the purpose of supplying and service pipes. Due to the presence of the openings in the concrete beams lead to the formation of cracks around the openings due to the stresses concentration in a small area above and below of the opening. The repairing, maintenance, and upgrading of structural members, are maybe one of the most pivotal problems in civil engineering applications. In this research, an experimental work is conducted to study the behavior of the reinforced RPC T-beams that containing openings and repair this beams using CFRP strips. The Experimental program of the present study includes two parts, the first part includes testing of seven reinforced reactive powder concrete RPC T-beams, which casted and tested, one beam is without opening as a reference beam and the rest, were provided with an opening. and these beams are divided into two groups. The first group was used to study the effect of the openings shape (circular and square) and the second group was used to study the effect of the openings locations, which consists three locations (Lc/2, Lc/3 and Lc/4).These are measured from the support center to the openings center. While the second part including a repaired all beams in the first part the using carbon fiber polymer. The test results indicated that the presence of openings in the beams web caused a reduction in the reinforced RPC T-beams ultimate load carrying capacity with about (10-55)%, Also lead to increasing in deflection compared to control beam before repairing at same loading. Studying the shape effect showed that the beams with square openings have average ultimate load carrying capacity lower by 36% compared with the control beams.While beams with containing circular openings have average ultimate load carrying capacity lower 29%. From the test results, it could be concluded that the presence of the openings in the shear region led to a decrease in ultimate load carrying capacity a about 38% to 49% for opening of opening at (Lc/3 and Lc/4) respectively. While the presence of openings in the flexural region led to a decrease in the ultimate load carrying capacity rate of 11%. Related to the repairing study part it was found that the average ultimate load carrying capacity for repairing beams was 103% compared with the not repaired beams.

scholarly journals Experimental and Analytical Studies on Strengthened Axially Loaded RC Columns

2021 ◽  
Vol 18 (17) ◽  
Author(s):  
Tejash K PATEL ◽  
Sanjay R SALLA ◽  
Sandip A VASANWALA ◽  
Chetankumar D MODHERA ◽  
Darshan PATEL ◽  
...  
Keyword(s):  
Load Capacity ◽  
Test Results ◽  
Stress Strain ◽  
Rc Columns ◽  
Rc Column ◽  
Strain Behavior ◽  
Load Carrying ◽  
Current Scenario ◽  
Strengthening Technique ◽  
Concrete Strengthening

The strengthening and retrofitting of concrete structures are becoming an essential part of the building and its structures. When the building comes of age, there is a need to increase the structural members' strength, life, and resistivity against unfavorable environmental conditions. In the current scenario, ferrocement composites are used for structural strengthening and rehabilitation. Therefore, an experimental investigation is needed to evaluate the effectiveness of the strengthening on the square and circular reinforced concrete columns by ferrocement and micro concrete materials. The experimental results showed that the ferrocement and micro concrete techniques enhanced the stress-strain behavior and displacement limit of the square and circular RC column. The strengthening circular RC column by micro concrete gives a better performance in stress-strain behavior and displacement limit. In addition, the ferrocement and micro concrete strengthening technique is a promising and economical alternative compared to the other strengthening techniques. Also, test results were compared with ACI and CNR–DT representative load-carrying models to verify each model's reliability and accuracy. Furthermore, the TOPSIS method was adopted to find out the best solution for square and circular columns, and cost analysis was carried out. HIGHLIGHTS RC columns were strengthened using ferro cement and micro concrete RC Columns under compressive concentric load were tested Micro concrete strengthening controls deflection and enhances the load capacity of columns The analytical approach of TOPSIS was used to find the best solution GRAPHICAL ABSTRACT

Long-Term Deformations of Steel-Reinforced Concrete Columns under Sustained Axial Loads

2013 ◽  
Vol 351-352 ◽  
pp. 645-649
Author(s):  
Zhou Yi Chen ◽  
Yang Wang ◽  
Jian Qing Wu
Keyword(s):  
Reinforced Concrete ◽  
Axial Loading ◽  
Test Results ◽  
Axial Loads ◽  
Steel Reinforced Concrete ◽  
Dependent Behavior ◽  
Shrinkage And Creep ◽  
Long Term Behavior ◽  
Creep And Shrinkage

Steel-reinforced concrete (SRC) columns have been widely used over the past few decades. However, very limited research has been conducted on the time-dependent behavior of these columns caused by creep and shrinkage under sustained loading. This paper presents the results of an experimental study of the long-term behavior of short SRC columns under sustained axial loading. Long-term axial deformations due to shrinkage and creep of the concrete were recorded. In analysis of the test results, time analysis of the SRC columns under sustained axial loads using the age-adjusted effective modulus method was proven to be suitable by employing the ACI 209 model for prediction of shrinkage and the CEB-FIP90 model for the prediction of creep.

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