scholarly journals COMPARATIVE STUDY OF THE REINFORCED STEEL BARS OBTAINED FROM A FAILED RESIDENTIAL BUILDING AND THE SHELVES

2021 ◽  
Vol 15 (2) ◽  
pp. 128-138
Author(s):  
Oluwatoyin Olaseinde ◽  
O. Ajanaku ◽  
O. M. Ojo ◽  
S. O. Seidu
Keyword(s):  
Comparative Study ◽  
Testing Machine ◽  
Residential Building ◽  
Time Interval ◽  
Percentage Elongation ◽  
Building Collapse ◽  
Reinforcing Bar ◽  
Steel Bar ◽  
Steel Bars ◽  
Reinforced Steel

Nigeria is a developing nation, the need to build structures is on high rise. The rate of structure failure and building collapse is also on the rise. This paper presents a comparative study on Mechanical Properties of Reinforced steel bars obtained from the shelves, and that obtained from the failed structure of a residential building which is then compared to International standard NO-432 . Steels are main reinforcing materials for most structural buildings, but when the integrity is compromised, it leads to devastating consequences. The quality of concrete and steel reinforcement must be such that has appropriate yield strength so that the structure can sustain the require load within the required time interval. The Ultimate Tensile Strength and percentage elongation of the steel bars obtained from the two sources were investigated. One of the sources was a reinforcing bar used in Millennium Estate, Mary Land, Lagos State, Nigeria. The steel bar samples of sizes 10mm and 16mm diameter were subjected to mechanical testing using a universal testing machine. The percentage elongation met with the standards while the 16mm samples are below the standards for both the failed structure and shelves.

Dynamic Behaviour of Reinforcing Steel Bars in Tension

2011 ◽  
Vol 82 ◽  
pp. 86-91 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Nicoletta Tesio
Keyword(s):  
Testing Machine ◽  
Maximum Load ◽  
Gauge Length ◽  
Strain Rates ◽  
Reinforcing Bars ◽  
Static Tests ◽  
Split Hopkinson Tensile Bar ◽  
Steel Bars ◽  
Split Hopkinson ◽  
Reinforced Steel

In this paper the preliminary results of the tensile behavior of reinforced steel in a large range of strain rates are presented. Tensile testing at several strain rates, using different experimental set-ups, was carried out. For the quasi-static tests a universal electromechanical testing machine with the maximum load-bearing capacity of 50 kN was used, while for the intermediate and high-strain rate regimes a hydro-pneumatic apparatus and a JRC-Split Hopkinson Tensile Bar respectively were used. The target strain rates were set at the following five levels: 10-3, 30, 250, 500, and 1000 1/s. The specimens used in this research were round samples having 3mm in diameter and 5mm of gauge length obtained from reinforcing bars. Finally, the material parameters for Cowper-Symonds and Johnson-Cook models were determined.

Evaluation on the Addition of Inhibitor and Surface Treatment to Corrosion Behavior of the Reinforced Steel Bar Embedded in Mortar Specimen

2017 ◽  
Vol 744 ◽  
pp. 114-120
Author(s):  
Kyung Man Moon ◽  
Sung Yul Lee ◽  
Jae Hyun Jeong ◽  
Myeong Hoon Lee
Keyword(s):  
Current Density ◽  
Test Specimen ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Steel Bars ◽  
Reinforced Steel ◽  
One Year

In this study, seven types of mortar test specimens were manufactured with parameters, that is, the surface of the reinforced steel bar was treated with hot dip galvanizing (Zn) and the surface of the test specimen was coated with underwater paint, and four types of inhibitors (DAW, MCI, DCI, and Silcon) were added in mortars respectively. And, the seven types of mortar test specimens were immersed in seawater for 4 years. The corrosion properties of the reinforced steel bars embedded in mortar test specimens were investigated using electrochemical methods. The corrosion potentials of the test specimens with painting on the surface of the specimen and Zn coating on the surface of the steel bar exhibited the noblest and lowest values respectively after one year, however, after 4 years, the specimens of underwater painting and of addition of Silcon inhibitor indicated the noblest and lowest values of corrosion potentials respectively. Furthermore, the painting specimen exhibited the smallest values of corrosion probability as welll as of the corrosion current density, while, addition of MCI inhibitor showed the highest values of both corrosion probability and corrosion current density. Moreover, the painting specimen showed the smallest value of neutralization degree among all the specimens, and the largest value of neutralization degree was observed at the specimen of natural condition (no adding of inhibitor, no painting and no Zn coating). As a result, it is considered that the addition of inhibitors, coating with hot dip galvanizing (Zn), and painting on the surface have the effects not only to inhibit the neutralization degree but also to increase the corrosion resistance of the embedded steel bar.

scholarly journals ULTRASONIC PULSE VELOCITY TEST OF REINFORCED CONCRETE WITH INDUCED CORROSION

2017 ◽  
Vol 7 (2) ◽  
pp. 9-17 ◽  
Author(s):  
Jason Maximino Co Ongpeng
Keyword(s):  
Reinforced Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Reinforcing Bars ◽  
Accelerated Corrosion ◽  
Steel Bar ◽  
Significant Damage ◽  
Steel Bars ◽  
Reinforced Steel

Non-destructive test has been applied to measure damage in structures. Common structures are assessed with the use of practical and easy application of ultrasonic pulse velocity (UPV). In this paper, the damage brought by corrosion was investigated using Proceq Punditlab having 54 kHz transducers oriented in direct transmission under the UPV. Fifty-four reinforced concrete of size 150 mm x 250 mm x 300 mm with two 10mm diameter reinforcing bars (Grade 40) and one 6mm diameter stainless steel bar (Type 304) was cast and tested. It had varying water cement ratio of 45%, 50%, and 55%with two conditions at day 0 (after curing), day 14, and day 28: non-accelerated condition under air-drying and accelerated condition using impressed current technique (ICT). The UPV test was conducted in each layer where reinforced steel bars were present and absent. It was found out that UPV test results was insignificant to all non-accelerated concrete, while it indicated significant damage for accelerated corrosion rate of more than 8 mm per year. In accelerated condition, the decrease in strength under UPV test was more than 20% for all specimens along the reinforced bars, and less than 15% for all specimens along the layer with no steel bars. This showed that the effect of corrosion greatly affects the entirety of structures near and far from the placement of reinforcing steel bars.

The Experimental Study on Concrete-Filled Thin-Walled Square Steel Box Short Columns Fixed with Composite Steel Bar

2011 ◽  
Vol 94-96 ◽  
pp. 1590-1595
Author(s):  
Hai Chao Wang ◽  
Xi Quan Xu ◽  
Li Jun Zhou
Keyword(s):  
Bearing Capacity ◽  
Concrete Strength ◽  
Testing Machine ◽  
Short Columns ◽  
Steel Bar ◽  
Bonding Effect ◽  
Steel Bars ◽  
Thin Walled ◽  
Transverse Steel ◽  
Composite Steel

The method of construction about the concrete-filled thin-walled square steel box short columns is studied in this paper. Composite steel is designed inside of the concrete-filled thin-walled square steel box short columns. The use of the transverse steel bars’ constraining effect on the concrete and bonding effect on the walls enhances the local stability and bearing capacity of the wall. According to the concrete strength C30/C35/C40 and the thickness of the steel 1.25mm/1.75mm/2.5mm,42 short column specimens are made and the size of all specimens is 200mm×200mm×690mm.The static bearing capacity test is done by the 500-ton electro-hydraulic serve testing machine. The whole curve is made .The composite steel and the thin-walled steel’s strain is tested. The results show that this method of construction has a certain effect on constrainting concrete and bonding effect on the walls, significantly improving their mechanical properties, increasing the carrying capacity and ductility, and it is easy to be accomplished.

Impalement with Spinal Cord Injury Requiring Intraoperative Division of a Reinforced Steel Bar

2005 ◽  
Vol 31 (5) ◽  
pp. 503-507 ◽  
Author(s):  
Madison Macht ◽  
Adnan Rizvi ◽  
Martin A. Schreiber ◽  
W. Slate Wilson
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Steel Bar ◽  
Cord Injury ◽  
Reinforced Steel

scholarly journals A COMPARATIVE STUDY OF RECENTLY ISOLATED HUMAN STRAINS AND A PASSAGE STRAIN OF POLIOMYELITIS VIRUS

1933 ◽  
Vol 58 (5) ◽  
pp. 513-529 ◽  
Author(s):  
John R. Paul ◽  
James D. Trask
Keyword(s):  
Comparative Study ◽  
Human Strain ◽  
Time Interval ◽  
Subsequent Infection ◽  
Poliomyelitis Virus ◽  
Intracerebral Inoculation ◽  
Human Sera ◽  
Cross Immunity ◽  
Experimental Disease

1. Confirmation of the qualitative differences which exist between so called human and passage strains of poliomyelitis virus has been established by the following observations. (a) The experimental disease induced by two human strains usually failed to protect monkeys against a subsequent infection by a passage strain, and in the few instances in which the reverse experiment could be tried a similar lack of protection was observed. (b) In some human sera the neutralizing power for a human strain differed qualitatively from the neutralizing power for a passage strain. 2. The time interval between the intracerebral inoculation of heterologous strains has been found to be an important factor bearing upon the results of the reinoculation experiments reported. Within the intervals used, the greater the period between the original infection and the reinoculation with a heterologous strain, the less was the degree of cross-immunity observed.

scholarly journals The calculation of building cooling under emergency conditions to ensure their heating reliability

Vestnik MGSU ◽  
2019 ◽  
pp. 496-501 ◽  
Author(s):  
Oleg D. Samarin
Keyword(s):  
Cooling Rate ◽  
Heat Supply ◽  
Structural Characteristics ◽  
Initial Period ◽  
Residential Building ◽  
Climatic Conditions ◽  
Time Interval ◽  
Basic Equations ◽  
Building Cooling ◽  
Air Exchange

Introduction. Continuation of research in the area of premise cooling rate calculation with the aim of obtaining dependencies, which are sufficiently accurate and take into account the most of the factors essential for the problem, but at the same time having an engineering form, is still relevant. The purpose of the study is the search for a dependence of the temperature in the building premises on time in the initial period after heat supply shutdown at emergency mode. Exponential nature of this dependence is considered as a scientific hypothesis. Materials and methods. The basic equations connecting the most important components of a heat flow in a cooling room under condition of the termination of heat supply from heating devices are used and analysed in the study. A numerical model of non-stationary thermal regime of the ventilated room is implemented on the base of the solution of a differential equations system of heat conduction and heat transfer on the surfaces of the room. Results. An analytical expression is obtained for the room cooling rate when the heat supply is disconnected, which has the form of an exponential function of square root of time since the accident. The cooling time before the condensation on the inner surface of the enclosure is determined by the example of a currently existing residential building under climatic conditions of Moscow, accounting the structural characteristics of the building and normalized fresh-air flow rate. Conclusions. It is shown that the building cooling in the initial period is influenced mainly by the ratio of the heat flux associated with unorganized air exchange and the heat loss to the environment through “light” enclosure. It was found that the decrease of natural air exchange in the building cooling process leads to a certain slowdown in the decrease of temperature, but it is not decisive. It is understood that the use of airtight light opening fillers, for example, in plastic casement, under normal conditions aggravating the sanitary and hygienic situation in the premises, under emergency conditions increases the available time interval for the restoration of heat supply.

scholarly journals A High Precision Quality Inspection System for Steel Bars Based on Machine Vision

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2732 ◽  
Author(s):  
Xinman Zhang ◽  
Jiayu Zhang ◽  
Mei Ma ◽  
Zhiqi Chen ◽  
Shuangling Yue ◽  
...  
Keyword(s):  
Machine Vision ◽  
High Precision ◽  
Absolute Error ◽  
Detection Methods ◽  
Inspection System ◽  
Quality Inspection ◽  
Construction Site ◽  
High Definition ◽  
Steel Bar ◽  
Steel Bars

Steel bars play an important role in modern construction projects and their quality enormously affects the safety of buildings. It is urgent to detect whether steel bars meet the specifications or not. However, the existing manual detection methods are costly, slow and offer poor precision. In order to solve these problems, a high precision quality inspection system for steel bars based on machine vision is developed. We propose two algorithms: the sub-pixel boundary location method (SPBLM) and fast stitch method (FSM). A total of five sensors, including a CMOS, a level sensor, a proximity switch, a voltage sensor, and a current sensor have been used to detect the device conditions and capture image or video. The device could capture abundant and high-definition images and video taken by a uniform and stable smartphone at the construction site. Then data could be processed in real-time on a smartphone. Furthermore, the detection results, including steel bar diameter, spacing, and quantity would be given by a practical APP. The system has a rather high accuracy (as low as 0.04 mm (absolute error) and 0.002% (relative error) of calculating diameter and spacing; zero error in counting numbers of steel bars) when doing inspection tasks, and three parameters can be detected at the same time. None of these features are available in existing systems and the device and method can be widely used to steel bar quality inspection at the construction site.

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