scholarly journals EXPERIMENTAL COMPRESSION TESTS OF COLD-FORMED STEEL (CFS) TO VERIFY ITS CODE-BASED STRENGTH

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Bernardo Lejano ◽  
James Matthew De Jesus ◽  
Arvin Patrick Yu
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
The Philippines ◽  
Structural Performance ◽  
Computational Aspect ◽  
Compression Tests ◽  
Flexural Buckling ◽  
Cold Formed Steel

Cold-Formed Steel (CFS) is a good construction material because of its high strength-to-weight ratio, that is, it exhibits efficient load carrying capabilities in combination with its lightweight characteristics. Although CFS is already being used in construction, information on structural performance of locally-produced CFS in the Philippines is scarce. To date, the authors have not found any experimental study done in the Philippines regarding the structural performance of locally-produced CFS. In this study, C-section and Z-section are being studied since these members exhibit buckling failures that may be difficult to predict due to complexity of their section geometry. The objective of this paper is to present the performance of these CFS sections when subjected to concentric axial compression both experimentally and computationally. For the experimental part, the CFS members were subjected to axial compression using a hydraulic jack. High-speed video cameras were used to capture the different failure modes. For the computational aspect, provisions found in the National Structural Code of the Philippines (NSCP) were used to calculate the compression strength of the members. A total of 80 C-section specimens with 5 different lengths and 5 different thicknesses were tested. It was found that the strength calculations using the NSCP provisions were not consistent with the results of the compression tests. For shorter lengths, distortional buckling prevailed as the main failure, while for longer lengths, torsional-flexural buckling occurred. All of the predicted strengths were highly conservative. For the Z-section, a total of 180 specimens with 6 different lengths and 6 different thicknesses were tested. Torsional-flexural buckling was observed in majority of the specimens. Although most of the failure modes were predicted correctly, it was found that the predicted strengths using the NSCP were relatively high compared to the experimental results, thus non-conservative. Finite Element Method (FEM) analyses using ANSYS were conducted. Findings indicate that the experiment results agreed well with the FEM results.

C-section Cold-Formed Steel as Structural Members in Housing Construction in the Philippines

2019 ◽  
Author(s):  
Bernardo A. Lejano
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
High Strength ◽  
The Philippines ◽  
Bending Test ◽  
Housing Construction ◽  
Distortional Buckling ◽  
Cold Formed Steel

<p>Getting good lumber for housing construction is becoming difficult in the Philippines due to existing partial log ban. Although, the use of reinforced concrete is still the most popular in construction, an emerging alternative is the use of cold-formed steel (CFS). It is gaining popularity because of its high strength-to- weight ratio. However, information about the structural performance of locally-produced cold-formed steel is almost nonexistent. Although, design provisions are stipulated in the local Code, these are based on formulas developed abroad, hence the need to investigate these cold-formed steel. This study focuses on the C-section cold-formed steel, which is the most popularly used. The objective is to verify its performance when subjected to axial compression and flexure, both experimentally and computationally. For the computational part, the formulas stipulated in the National Structural Code of the Philippines were followed. For the experimental part, the cold-formed steel members were subjected to compression loads and flexural loads. Aside from usual sensors, high-speed cameras were used to capture the failure modes. For axial compression test, 80 specimens with different lengths and thicknesses were tested. For flexure, 24 specimens of back-to-back C-sections were subjected to 4-point bending test. Results showed the predicted strengths were well below the experimental values. In design, this means the use of Code-based formulas is conservative. Failure modes observed were torsional buckling and distortional buckling. Comparison of failure modes between experiment and computation shows 70% agreement for compression and 75% for flexure. Finite element method calculations were also done and were compared with experimental results.</p>

Cold-formed steel framing walls with infilled lightweight FGD gypsum Part II: Axial compression tests

2018 ◽  
Vol 132 ◽  
pp. 771-782 ◽  
Author(s):  
Hanheng Wu ◽  
Sisi Chao ◽  
Tianhua Zhou ◽  
Yunxiao Liu
Keyword(s):  
Axial Compression ◽  
Compression Tests ◽  
Fgd Gypsum ◽  
Steel Framing ◽  
Cold Formed Steel

scholarly journals Experimental Study on the Skidding Damage of a Cylindrical Roller Bearing

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4075 ◽  
Author(s):  
Qing Zhang ◽  
Jun Luo ◽  
Xiang-yu Xie ◽  
Jin Xu ◽  
Zhen-huan Ye
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Failure Modes ◽  
Roller Bearing ◽  
Weight Ratio ◽  
Operating Conditions ◽  
Roller Bearings ◽  
Light Load ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

As large-scale rotating machines develop toward high rotating speed and high power–weight ratio, skidding damage has become one of the major initial failure modes of cylindrical roller bearings. Therefore, understanding the skidding damage law is an effective way to ensure the safety of machines supported by cylindrical roller bearings. To realize the skidding damage, a high-speed rolling bearing test rig that can simulate the actual operating conditions of aviation bearings was used in this paper, and the skidding damage dynamic behaviors of cylindrical roller bearings were investigated. In addition, to ensure the accuracy of the obtained skidding damage mechanism, the cylindrical roller bearing was carefully inspected by microscopic analysis when the skidding damage occurred. Out results show that instantaneous increases in friction torque, vibration acceleration, and temperature are clearly observed when the skidding damage occurs in the cylindrical roller bearing. Furthermore, under the conditions of inadequate lubrication and light load, the critical speed of skidding damage is rather low. The major wear mechanisms of skidding damage include oxidation wear, abrasive wear, and delamination wear. The white layers are found locally in the inner ring and rollers under the actions of friction heat and shear force.

scholarly journals Study on the Mechanical Properties of BFRP Tube Confined Concrete Short Columns under Axial Compression

2020 ◽  
Author(s):  
Xindong Ding ◽  
Shuqing Wang ◽  
Yu Liu ◽  
Zepeng Zheng
Keyword(s):  
Axial Compression ◽  
Brittle Failure ◽  
Failure Modes ◽  
Concrete Strength ◽  
Steel Tube ◽  
Confined Concrete ◽  
Test Results ◽  
Compression Tests ◽  
Short Columns ◽  
Square Steel Tube

Axial compression tests were carried out on 6 square steel tube confined concrete short columns and 6 BFRP square pipe confined concrete axial compression tests. The concrete strength grades were C30, C40, and C50. The test results show that the failure modes of steel pipe and BFRP pipe are obviously different, and the BFRP pipe undergoes brittle failure. Compared with the short columns of concrete confined by BFRP pipes, the ultimate bearing capacity of axial compression is increased by -76.46%, -76.01%, and -73.06%, and the ultimate displacements are -79.20%, -80.78%, -71.71%.

scholarly journals Study on the Mechanical Properties of BFRP Tube Confined Concrete Short Columns under Axial Compression

2020 ◽  
Author(s):  
Xindong DING ◽  
Shuqing Wang ◽  
Yu Liu ◽  
Zepeng Zheng
Keyword(s):  
Axial Compression ◽  
Brittle Failure ◽  
Failure Modes ◽  
Concrete Strength ◽  
Steel Tube ◽  
Confined Concrete ◽  
Test Results ◽  
Compression Tests ◽  
Short Columns ◽  
Square Steel Tube

Axial compression tests were carried out on 6 square steel tube confined concrete short columns and 6 BFRP square pipe confined concrete axial compression tests. The concrete strength grades were C30, C40, and C50. The test results show that the failure modes of steel pipe and BFRP pipe are obviously different, and the BFRP pipe undergoes brittle failure. Compared with the short columns of concrete confined by BFRP pipes, the ultimate bearing capacity of axial compression is increased by -76.46%, -76.01%, and -73.06%, and the ultimate displacements are -79.20%, -80.78%, -71.71%.

scholarly journals Composite Timber Panel Optimization for a New-type Cold-Formed Steel Shear Wall

2017 ◽  
Vol 11 (1) ◽  
pp. 255-273 ◽  
Author(s):  
Jun He ◽  
Jing Li ◽  
Zhuoyang Xin ◽  
Weian Jiang
Keyword(s):  
Failure Modes ◽  
Shear Wall ◽  
Structural Performance ◽  
Strain Gauges ◽  
Performance Parameters ◽  
Steel Shear Wall ◽  
New Type ◽  
Cold Formed Steel ◽  
Reversed Cyclic

Background and Methods: This paper illustrates a research on the behavior of the composite timber panels used in a new-type cold-formed steel shear wall, when subjected to monotonic and reversed cyclic in-plane loading. The framing members of this new-type cold-formed steel shear wall are made of cold-formed steels. The inner timber frameworks, sheathed with veneer plywood, form the composite timber panels. Objective: In order to improve the lateral performance of the new-type cold-formed steel shear wall, two different optimized composite timber panels were proposed and tested, namely, increasing the thickness of the sheathings and the addition of steel X-bracings. The main objective of the study is to determine the quantification of the improvement in lateral performance of these two optimized composite timber panels. Results and Conclusion: Observed failure modes, structural performance parameters and the data of the strain gauges were given for each specimen, which indicates two optimized panels both have better lateral performance. But larger deformation and damage of the sheathings happened on the panels with steel X-bracings, so the panels with thick sheathings are more suitable and practical for normal use.

Experimental Investigation on Wide-Span Cold-Formed Steel Roof Truss System

2012 ◽  
Vol 166-169 ◽  
pp. 1304-1307 ◽  
Author(s):  
Shahrin Mohammad ◽  
M.Md. Tahir ◽  
Cher Siang Tan ◽  
Poi Ngian Shek
Keyword(s):  
Construction Industry ◽  
Failure Modes ◽  
Environmental Conservation ◽  
Structural Performance ◽  
Total Load ◽  
Roof Truss ◽  
Cold Formed Steel ◽  
Thin Walled ◽  
The Stability ◽  
Stability Issues

The needs of environmental conservation and speed development in construction industry today have forced the search for better technologies in structural roof truss construction. Cold-formed section is a better choice for roof truss system in sustainable design with several advantages e.g. reduce cutting down of trees, speedy in construction, stronger, lighter and flexible in erection. However the stability issues occurred when wide-span roof truss is implemented with thin-walled cold-formed steel member. A full scale testing for a 25 meter wide-span roof truss system was carried out at Universiti Teknologi Malaysia to study the structural performance. The overall span of the truss is 25m in length with the height of 4.7m and the width of 1.2 m, built up by cold-formed steel channel sections of 150 mm and 74 mm in depth. Uniform loads were placed on the top and bottom chords of the truss using cement bags. The roof truss deformed at a total load of 63.77 kN or 52.7% of the designed load. Failure modes of the truss system were being observed and discussed for further improvement of the truss design.

Experimental study on cold-formed steel lipped channel medium-long columns strengthened longitudinally by steel strips or steel bars

2021 ◽  
pp. 136943322110115
Author(s):  
Jianfeng Chen ◽  
Xinxin Yang ◽  
Shen Yongkang ◽  
Mingqi Chen
Keyword(s):  
Initial Stress ◽  
Axial Compression ◽  
Stress Ratio ◽  
Large Deviation ◽  
Compression Tests ◽  
Distortional Buckling ◽  
Steel Strips ◽  
Steel Bars ◽  
Cold Formed Steel ◽  
Stress Ratios

Based on the existing methods of reinforcing cold-formed steel lipped channel column, this paper proposed that reinforced the cold-formed steel lipped channel column longitudinally with steel strips or steel bars for the first time. In order to study the influence of section forms and initial stress ratio on axial compression behavior of columns, a series of pin-pin ends axial compression tests were conducted. The experiment specimens contained 20 concentrically loaded specimens with two cross-section shapes, four initial stress ratios, respectively. It was shown that when reinforcing column longitudinally with the reinforcement, under axial compression, the ultimate bearing capacity of the specimens could significantly increase with little change in the quantity of steel. Moreover, the reinforcing effect of the column decreased linearly with an increase in the initial stress ratio ( β) of the load-strengthened specimens. Here, unloading or partial unloading reinforcement was recommended, and the initial stress ratio should be lower than 0.3. Finally, the experimental results were compared with the calculation results for the axial bearing capacities of the column based on the current Chinese standard (GB50018-2002) and North American standard (AISI). It indicated that for the section prone to local-global interactive buckling, the result calculated by GB50018-2002 is more accurate, but has a large deviation in calculating the section prone to distortional buckling. Results of direct strength method of AISI are the opposite to the result of GB50018-2002.

scholarly journals Axial Compression Performance of Post-Fire Concrete Columns Strengthened Using Thin-Walled Steel Tubes

2019 ◽  
Vol 11 (18) ◽  
pp. 4971
Author(s):  
Luo ◽  
Su ◽  
Xu ◽  
Ou ◽  
Peng
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Columns ◽  
Thin Wall ◽  
Compression Tests ◽  
Steel Tubes ◽  
Compression Performance ◽  
Ultimate Deformation ◽  
Thin Walled

For concrete columns damaged by fire, a strengthen technique using thin-walled steel tubes is proposed. To investigate the axial compression capacity of post-fire concrete columns strengthened using thin-walled steel tubes, considering tube thickness, the strengthening method, and section geometry, 12 specimens were fabricated, of which two were control columns and 10 were exposed to fire in accordance with the ISO834 temperature curve. Subsequently, eight specimens were strengthened. Axial compression tests were conducted to provide a better understanding of the strengthening technique. The experiments indicated that: (1) Different failure modes were observed for different cross section geometry—local bucking for square sections, and shear failure for circular sections. (2) The stiffness, axial strength, and ultimate deformation capacity of the enhanced columns may be rehabilitated and even better than the undamaged ones. (3) Two enhancement methods were compared. The steel tubes act as restraints, are merely subjected to tension, and provide strong restraint to the core concrete. The tube carrying load together with the concrete columns are mainly subject to compression, and likely to buckle with longitudinal strain. Finally, axial compressive equations of post-fire reinforced concrete (RC) with thin-wall steel tubes, including both square sections and circle sections, were proposed on the mechanism of concrete filled steel tubes.

Application of Minimum Quantity Lubrication when Drilling Nickel-Based Superalloy at High Cutting Speed

2009 ◽  
Vol 407-408 ◽  
pp. 612-615 ◽  
Author(s):  
Erween Abdul Rahim ◽  
Hiroyuki Sasahara
Keyword(s):  
Feed Rate ◽  
High Speed ◽  
Failure Modes ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Weight Ratio ◽  
Minimum Quantity Lubrication ◽  
Machined Surface ◽  
Minimum Quantity ◽  
Coated Carbide

Nowadays, an increase on demands of aerospace components has led to implementation of high speed machining (HSM). The principal factors in the performance of aerospace materials are strength-to-weight ratio, fatigue life, fracture toughness, survivability and of course, reliability. However, when HSM is coupled with dry or near dry machining, it will present considerable technical challenges to the manufacturing sector especially when the integrity of the machined surface is concerned. In this investigation, the effect of high speed drilling (HSD) conditions on the performance and surface integrity of Inconel 718 were studied. Hole was drilled individually using TiAlN coated carbide insert drill (14 mm in diameter) under minimum quantity of lubrication (MQL) condition. Results showed that uniform flank wear and chipping were the dominant tool failure modes. Moreover, the results showed an increase in cutting temperature with increasing cutting speed and feed rate. Thrust force and torque decreased linearly with the increasing cutting speed but significantly increased when higher feed rate is employed. Cutting speed significantly influenced the distribution of surface roughness value. Variations of hardness readings were recorded beneath the machined surfaces, they were due to the hardening effects caused by concentration of high temperature and stresses on the workpiece.

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