Pre-Test and Analysis of a Reinforced Concrete Slab Subjected to Blast From a Non-Confined Explosive

2018 ◽  
pp. 272-287
Author(s):  
Fausto B. Mendonça ◽  
Girum S. Urgessa
Keyword(s):  
Dynamic Analysis ◽  
Large Scale ◽  
Concrete Slab ◽  
Wave Parameter ◽  
Experimental Program ◽  
Small Scale ◽  
Maximum Displacement ◽  
Reinforced Concrete Slab ◽  
Test Experiment ◽  
Rc Slabs

A large scale experimental program consisting of testing 10 RC slabs with different variations of concrete compressive strength, reinforcement ratio and retrofit was conducted in Brazil. As part of that test program, a small-scale blast pre-test setup and associated dynamic analysis were conducted in order to confirm the proper functioning of the blast test sensors (pressure gages, displacement meter and accelerometers). The results of the pre-test were compared with theoretical blast wave parameter predictions using established equations and maximum displacement predictions using simplified dynamic analysis. The pre-test experiment provided useful insights and was shown to be critical for the success of the subsequent large scale blast tests.

scholarly journals Comparison of Predicted and Experimental Behaviour of RC Slabs Subjected to Blast using SDOF Analysis

2018 ◽  
Vol 68 (2) ◽  
pp. 138 ◽  
Author(s):  
F. B. Mendonca ◽  
G. Urgessa ◽  
K. Iha ◽  
R. J. Rocha ◽  
J.A.F.F. Rocco
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Experimental Program ◽  
Reinforced Concrete Slab ◽  
Peak Displacement ◽  
Blast Damage ◽  
Reinforced Concrete Slabs ◽  
Military Facilities ◽  
Rc Slabs ◽  
Sdof Analysis

<p>Explosions emanating from terrorist attacks or military weapons cause damage to civilian and military facilities. Understanding the mechanical behaviour of reinforced concrete structures subjected to blast is of paramount importance for minimizing the possible blast damage. A full-scale experimental program consisting of six reinforced concrete slabs with compressive strengths of 60 MPa, 50 MPa and 40 MPa, measuring 1.0 m × 1.0 m × 0.08 m, and subjected to 2.7 kg of non-confined plastic bonded explosive, was conducted in blast test area of Science and Technology Aerospace Department (Brazilian Air Force). This paper compares experimentally measured peak displacement values with theoretical values. Theoretical analysis was carried out using single degree of freedom (SDOF) models. The comparison showed that SDOF analysis worked very well in predicting the reinforced concrete slab peak displacement against blast effects. Qualitative analysis after the experiments showed that the blast wave shape generated by the cylindrical explosive was not uniformly distributed on the slabs for the standoff distance of 0.927 m∕kg1/3.<br /><br /></p>

Strain monitoring in a reinforced concrete slab sustaining service loads by distributed Brillouin fibre optic sensors

2010 ◽  
Vol 37 (10) ◽  
pp. 1341-1349 ◽  
Author(s):  
Beatriz Martín-Pérez ◽  
Amre Deif ◽  
Bruno Cousin ◽  
Chunshu Zhang ◽  
Xiaoyi Bao ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Fibre Length ◽  
Experimental Program ◽  
Small Scale ◽  
Fibre Optic ◽  
Reinforced Concrete Slab ◽  
Rc Structures ◽  
Strain Monitoring ◽  
Rc Slab

Reinforced concrete (RC) structures deteriorate and as a result crack due to extreme loading and (or) environmental conditions. Damage accumulation as such adversely affects the structure’s durability properties, impairing its service life. The intensity of cracking in an RC structure is usually regarded as the key criterion toward damage assessment and repair intervention. This paper presents the results of an experimental program in which the concrete strains of a small-scale RC slab sustaining in-service loads were monitored by traditional electrical strain gauges and distributed Brillouin fibre optic sensors in an attempt to detect damage due to crack formation. A comparison of these measurements with classical bending theory is also presented. The results show that distributed Brillouin fibre optic sensors can capture both tensile and compressive strains in concrete; however, the accuracy of their measurements is dependent on the proper installation of the sensors and the fibre length over which the strains are to be measured.

Variation of Structural Capacity of Reinforced Concrete Slab Due to the Repeated Cyclic Loading Idealized for Thermal Load

2010 ◽  
Vol 452-453 ◽  
pp. 697-700
Author(s):  
Soo Yeon Seo ◽  
Seung Joe Yoon ◽  
Hyun Do Yoon
Keyword(s):  
Cyclic Loading ◽  
Concrete Slab ◽  
Weather Data ◽  
Effect Of Temperature ◽  
Reinforced Concrete Slab ◽  
Structural Capacity ◽  
Long Term Effect ◽  
Test Parameters ◽  
Rc Slabs

A variation of temperature by sunlight acting on a RC roof slab causes a change of stress in concrete since it expands during summer and is compressed during winter. This behavior repeats annually and affects structural capacity of member for both serviceability and ultimate level. In this paper, a variation of cyclic temperature loading is calculated by analyzing the weather data of Korea for 20 years. In addition, an experimental work is planned to find the long term effect of temperature change. Four RC slabs are made with same dimension. Test parameters are loading duration (10, 20, 30 years). Observation of stiffness variations according to cyclic loading duration shows that the serious stiffness drop happens after 10 year's cyclic loading at summer while after 30 year's loading at winter. From the failure test, maximum strength of specimen that experienced repeated preloading was approximately 12% less than standard specimen without any repeated preloading.

scholarly journals Performance of Reinforced Concrete Slab with Opening Strengthened Using CFRP

Fibers ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 25
Author(s):  
Syafiqah Shahrul Aman ◽  
Bashar S. Mohammed ◽  
Mubarak Abdul Wahab ◽  
Abdullah Anwar
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Fiber Reinforced Polymer ◽  
Sufficient Information ◽  
Reinforced Concrete Slab ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
Cfrp Sheet ◽  
And Performance ◽  
Rc Slabs

Openings in reinforced concrete (RC) slabs are not commonly prescribed in design codes. Even when they are, they raise concerns regards to the size of the openings and the location of the applied loads. Lack of sufficient information about the load-carrying capacity of the slabs with openings and performance is another concern. Hence, this research addresses the structural behavior of slabs with openings coated with Carbon Fiber Reinforced Polymer (CFRP) sheet. In the experimental part, ten slabs were cast with a dimension of 1000 mm × 530 mm × 25 mm, among which nine slabs had openings and one slab was without opening (control slab). The configuration of the CFRP sheet includes coating in the form of single, double, and triple layers. Experimental results show that the slab with a triple coating of the CFRP layer offers the maximum resistance towards the loading rate. Moreover, with the increase in CFRP layers, the value of deflection is minimized.

scholarly journals Reinforced concrete slabs subjected to thermal loads

1993 ◽  
Vol 20 (5) ◽  
pp. 741-753 ◽  
Author(s):  
F. J. Vecchio ◽  
N. Agostino ◽  
B. Angelakos
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Ultimate Load ◽  
Mechanical Load ◽  
Concrete Slab ◽  
Shear Behaviour ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Reinforced Concrete Slabs ◽  
Load Conditions

Eight large-scale reinforced concrete slab specimens were tested under combined thermal and mechanical load conditions. The specimens varied in the amount and orientation of the in-plane reinforcement provided. A three-phase loading regime was used to investigate thermal gradient effects at service and ultimate load conditions. The slabs experienced significant levels of stressing and cracking as a result of restrained thermal deformations. However, reductions in stiffness due to cracking and thermal creep caused rapid decays in the restraint forces developed. At ultimate load conditions, thermal load effects were minimal. Nonlinear finite element analysis procedures were used to investigate the theoretical response of the test slabs. Fairly accurate simulations of the specimens' behaviour were obtained. Important to achieving accurate results were the consideration of tension stiffening effects and out-of-plane shear behaviour. Key words: analysis, cracking, finite elements, plates, reinforced concrete, slabs, temperature, tests, thermal gradients.

Behavior of Two-way RC Slabs Combination Strengthened with CFRP Strips and Steel Sheets

2014 ◽  
Vol 501-504 ◽  
pp. 1048-1052 ◽  
Author(s):  
Xiao Jin Li ◽  
Yi Yan Lu ◽  
Na Li
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Concrete Slabs ◽  
Test Results ◽  
Reinforced Concrete Slab ◽  
Steel Sheets ◽  
Reinforced Concrete Slabs ◽  
Rc Slab ◽  
Rc Slabs ◽  
Strengthening Technique

A total of four two-way reinforced concrete slabs strengthened with three methods were tested. The four test specimens were one unstrengthened reinforced concrete slab (control), one slab strengthened with CFRP strips, one slab strengthened with steel sheets, and one slab strengthened with an innovative method of applying CFRP strips and steel sheets combination bonding to the tension face of the slab. The test results show the CFRP-Steel combination strengthened technique is a rapid and effective strengthening technique for two-way RC slab. The increase in ultimate capacities of CFRP-Steel combination strengthened slab is 221.1% over the control slab, 84.4% over the CFRP-strengthened slab, and 45.2% over the steel-strengthened slab. In addition, the CFRP-Steel combination strengthened slab exhibited superior ductility than the CFRP-strengthened slab.

Experimental Measurements and Computer Analysis of Heat of Hydration and Shrinkage of Large-Scale Model of Reinforced Concrete Slab

2014 ◽  
Vol 1004-1005 ◽  
pp. 1594-1597
Author(s):  
Petr Tej ◽  
Jindřich Čech ◽  
Jiří Kolísko ◽  
David Čítek ◽  
Jan L. Vítek
Keyword(s):  
Reinforced Concrete ◽  
Computer Analysis ◽  
Large Scale ◽  
Concrete Slab ◽  
Heat Of Hydration ◽  
Scale Model ◽  
Experimental Measurements ◽  
Reinforced Concrete Slab ◽  
Large Scale Model ◽  
Concrete Body

This paper deals with the experimental measurements and computer analysis of the development of heat of hydratation and shrinkage in a large-scale model of a reinforced concrete slab. A large-scale model was built in situ to experimentally verify the design of the reinforcement, with the aim of preventing the formation of cracks in slab. The model represents a four times four meters cut of a slab structure of a thickness of 1.6 m. Bars in the horizontal direction of the slab were extended behind the concrete body and welded to a steel frame, which simulated the anchorage of horizontal reinforcement of a continuous slab. Before casting, the reinforcement bars were fitted with vibrating wire strain gauges and with resistance gauges for monitoring the strain, as well as with temperature sensors for determining the temperature field caused by heat of hydration. According to the needs of the experiment, the structure was modelled in GiD 11.0 software and calculated in the AtenaWin program. The experimental results and the results obtained by a numerical analysis were compared.

scholarly journals Behavior of Self Compacting Reinforced Concrete One Way Bubble Deck Slab

2020 ◽  
Vol 23 (1) ◽  
pp. 1-11
Author(s):  
Ali H. Yaagoob ◽  
Ibrahem S. Harba
Keyword(s):  
Reinforced Concrete ◽  
Experimental Work ◽  
Ultimate Load ◽  
Concrete Slab ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Reinforced Concrete Slab ◽  
Ball Diameter ◽  
New Type ◽  
Deck Slab

Reinforced concrete slab with plastic voids (Bubbled Deck system) is a new type of slabs which has two-dimensional arrangement of voids within the slab that is developed to decrease the slab self-weight while maintaining approximately the same load carrying capacity as compared with the solid slabs. Plastic voided slabs have the ability to reduce concrete amount by about 30 percent and this reduction is so important in terms of cost saving and enhancement the structural performance. In this research paper investigation is carried out to study the shear strength behavior of one-way bubble deck slab using self-compacting reinforced concrete. The experimental program consists of testing thirteen one-way slabs with dimensions of (1700 length, 700 width and 150 thick) mm. One of the tested slabs is a solid slab (without balls) is used as a reference, the remaining twelve bubbled slabs with ball diameter (73, 60) mm are divided into five groups according to the parameters of the experimental work, the parameters of the experimental work include: type of slab (bubble and solid slabs), ball diameter (73, 60) mm, shear reinforcement and spacing between balls. The experimental results showed that the bubbled slabs without shear reinforcement have a decrease in the ultimate load as compared to solid slab by about 3.7% to 14.3% and an increase in the deflection at ultimate load by about 10% to 22%, at the same time the first crack load decreases by about 15.3% to 42.4% as compared to solid slab due to decreases of moment of inertia of bubble slab compared to solid slab. Also, the results showed that the bubbled slabs withe shear reinforcement (multi-leg) have an increase in the ultimate load as compared to solid slab by about 35.4% to 57.3% and an increase in the deflection at ultimate load by about 1% to 15%, at the same time the first crack load decreases by about 2.8% to 27.4% as compared to solid slab.

scholarly journals Natural Frequencies Reduction of RC Slab Subjected to Incremental Concentrated Loads

2019 ◽  
Vol 8 (3) ◽  
pp. 17
Author(s):  
Mezgeen S. Ahmed ◽  
Abdulhameed A. Yaseen ◽  
Fouad A. Mohammad
Keyword(s):  
Reinforced Concrete ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Concrete Slab ◽  
Experimental Modal Analysis ◽  
Experimental Program ◽  
Concentrated Loads ◽  
Reinforced Concrete Slab ◽  
Reinforced Concrete Slabs ◽  
Set Up

Reinforced concrete slabs are frequently used in many engineering structures such as buildings and bridges. Damages in an engineering structure including reinforced concrete slab are classified as light, moderate, and severe cracks. A special treatment is required for every typical crack-damage to strengthen its structure. The reinforced concrete slab experiencing cracks reduce stiffness as well as its strength. An experimental program was set up to establish a relation between cracks and changes of a dynamic system characteristics of the slab through natural frequencies. The aim is to perform experimental modal analysis (EMA) as a non-destructive vibration testing method for diagnosing the structural integrity of the slab. For this purpose, two RC square slabs specimens of dimensions 1200mm x 1200mm x 40mm were used. As a first part of the project, a reinforced concrete slab was subjected to an increasing partially concentrated loads at the slab’s center to introduce cracks. After each incremental load steps (5, 10, 12kN) the slab was unloaded. Then, a free-free set-up for the slab was established by using the flexible elastic ropes (bungee cords). After the dynamic test of 5, 10 and 12kN loads, the slab was strengthened using external CFRP sheets (type TR30S). Next, experimental modal analysis was performed to establish a relation between cracks and changes in natural frequencies of the slab. The overall trend of frequency decrease after occurring damage that would be expected for all modes. However, it is not guaranteed all modes have same sensitivity to the applied load that inflicts severe cracks.

Sign in / Sign up

Export Citation Format

Share Document