scholarly journals EVALUATION OF POST TENSIONED SLAB AND ITS CONTRAST WITH TRADITIONAL RCC SLAB: REVIEW

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Siddiqui Furkhan Ahmed
Keyword(s):  
Flat Plate ◽  
High Strength ◽  
Lateral Load ◽  
Concrete Slabs ◽  
Dead Load ◽  
The Past ◽  
Behavioural Characteristics ◽  
Live Loads ◽  
Post Tensioning ◽  
Post Tension

Post-tensioning is a technique for reinforcing concrete slabs with high-strength tendons. Tendons retain much more concrete in compression. Posttension floors are capable of bearing almost every dead load due to their tensioned tendons, which aid to perform live loads acts on slabs & make them stronger than traditional slabs. For commercial and residential floors, PT slabs are suggested for comparatively limited depths, less heavy weights and free floor elevation. The research on the R.C.C and PT slab has been reviewed, with an integrative impact with the lateral load. The primary aim of this, is to review the reaction and behavioural characteristics of the post-tension flat plate during an earthquake and to contrast it with the traditional slab. For this purpose, the past papers related to the PT slab were studied and a successful conclusion has been made.

scholarly journals Flexural Behavior Performance of Reinforced Concrete Slabs Mixed with Nano- and Microsilica

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Rakesh Kancharla ◽  
Venkata Rao Maddumala ◽  
T. V. N. Prasanna ◽  
Lokaiah Pullagura ◽  
Ratna Raju Mukiri ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Flexural Behavior ◽  
Concrete Slabs ◽  
The Past ◽  
Reinforced Concrete Slabs ◽  
Concrete Mix ◽  
Bending Behavior

Present technology has been evaluated greatly over the past decades, where new particles are being designed and fabricated to fulfill specific needs. The field of nano- and micromaterials has prospered in many disciplines. It has been recently used in reinforced concrete in the production of high-strength, high-performance concrete. Microsilica (MS) and nanosilica (NS) particles have proven to be highly profitable to the concrete mix. Concrete has become denser with considerable improvement in their mechanical characteristics, particularly compressive strength. This proposed method includes a comparative study of the flexural bending behavior of conventional reinforced concrete (without MS or NS) slabs with other slabs. Each has various mixes of MS and NS particles incorporated into the concrete mix. The material content utilized in the slabs is kept constant by replacing a portion of the cement with an equivalent amount of either NS or MS particles or both. MS particles are altered from 0, 5, and 10% while NS particles are altered from 0, 0.5, and 1.0%. It cracks the widths and has higher final load-bearing capacity.

Effect of Modeling Variables upon Projection of Corrosion-Induced Bridge Post-Tension Tendon Failures

CORROSION ◽  
10.5006/2710 ◽  
2018 ◽  
Vol 74 (7) ◽  
pp. 768-775 ◽  
Author(s):  
William H. Hartt
Keyword(s):  
Tensile Strength ◽  
Concrete Structures ◽  
Random Numbers ◽  
Tendon Length ◽  
The Past ◽  
Modeling Approach ◽  
Bridge Structures ◽  
Post Tensioning ◽  
Post Tension ◽  
Wire Strand

Construction via post-tensioning (PT) has evolved over the past 60 y as an often preferred approach to affecting integrity for large concrete structures. In the case of bridges, tendon ducts typically contain multiple 15.24 mm (0.600 in) diameter, seven wire strands of minimum tensile strength 1,960 kN (270 ksi), and are invariably grouted. However, failures have been reported as a consequence of corrosion caused by either chemically or physically deficient grout. In response to this a methodology was developed and reported whereby the timing of wire and strand fractures and tendon failures can be projected. The present paper reviews basics of the modeling approach and evaluates the influence of modeling variables upon failure projections. These variables include the following: (1) analysis variables (generation of random numbers), (2) strand/tendon stress, (3) wire/strand strength, (4) number of tendons, and (5) tendon length. The significance of each is discussed and results are related to the timing of tendon failures on bridge structures.

A new steel anchorage system for post-tensioning applications using carbon fibre reinforced plastic tendons

1998 ◽  
Vol 25 (1) ◽  
pp. 113-127 ◽  
Author(s):  
Ezzeldin Y Sayed-Ahmed ◽  
Nigel G Shrive
Keyword(s):  
Carbon Fibre ◽  
Prestressed Concrete ◽  
Fatigue Tests ◽  
Direct Tension ◽  
Element Analysis ◽  
Prestressing Steel ◽  
Reinforced Plastics ◽  
Anchorage System ◽  
Post Tensioning ◽  
Post Tension

During the past half century, the use of prestressing in different structures has increased tremendously. One of the most important techniques of prestressing is post-tensioning. The main problem associated with post-tensioning in different structures is the corrosion of the prestressing steel tendons even with well-protected steel. New materials, fibre reinforced plastics or polymers (FRP), which are more durable than steel, can be used for these tendons/strands and thus overcome the corrosion problem. However, different shortcomings appear when FRP tendons are introduced to post-tensioning prestressing applications. For carbon fibre plastic tendons (CFRP), there is no suitable anchorage system for post-tensioning applications. Some of the anchorages developed by others for use with FRPs are therefore described and assessed. A new anchorage system developed by the authors, which can be used with bonded or unbonded CFRP tendons in post-tensioning applications, is described. The results of direct tension and fatigue tests on CFRPs anchored with the new system are presented.Key words: anchorage system, cyclic loading, fatigue, fibre reinforced plastics, finite element analysis, post-tension, prestressed concrete, prestressed masonry, strands, tendons.

High-strength nitrogen removal of opto-electronic industrial wastewater in membrane bioreactor - a pilot study

2003 ◽  
Vol 48 (1) ◽  
pp. 191-198 ◽  
Author(s):  
T.K. Chen ◽  
C.H. Ni ◽  
J.N. Chen ◽  
J. Lin
Keyword(s):  
Wastewater Treatment ◽  
Industrial Wastewater ◽  
Organic Nitrogen ◽  
Membrane Bioreactor ◽  
High Strength ◽  
Experimental Period ◽  
Ammonia Nitrogen ◽  
Nitrifying Bacteria ◽  
Biological Degradation ◽  
The Past

The membrane bioreactor (MBR) system has become more and more attractive in the field of wastewater treatment. It is particularly attractive in situations where long solids retention times are required, such as nitrifying bacteria, and physical retention critical to achieving more efficiency for biological degradation of pollutant. Although it is a new technology, the MBR process has been applied for industrial wastewater treatment for only the past decade. The opto-electronic industry, developed very fast over the past decade in the world, is high technology manufacturing. The treatment of the opto-electronic industrial wastewater containing a significant quantity of organic nitrogen compounds with a ratio over 95% in organic nitrogen (Org-N) to total nitrogen (T-N) is very difficult to meet the discharge limits. This research is mainly to discuss the treatment capacity of high-strength organic nitrogen wastewater, and to investigate the capabilities of the MBR process. A 5 m3/day capacity of MBR pilot plant consisted of anoxic, aerobic and membrane bioreactor was installed for evaluation. The operation was continued for 150 days. Over the whole experimental period, a satisfactory organic removal performance was achieved. The COD could be removed with an average of over 94.5%. For TOC and BOD5 items, the average removal efficiencies were 96.3 and 97.6%, respectively. The nitrification and denitrification was also successfully achieved. Furthermore, the effluent did not contain any suspended solids. Only a small concentration of ammonia nitrogen was found in the effluent. The stable effluent quality and satisfactory removal performance mentioned above were ensured by the efficient interception performance of the membrane device incorporated within the biological reactor. The MBR system shows promise as a means of treating very high organic nitrogen wastewater without dilution. The effluent of TKN, NOx-N and COD can fall below 20 mg/L, 30 mg/L and 50 mg/L.

scholarly journals Ductility and flexure of lightweight expanded clay basalt fiber reinforced concrete slab

2021 ◽  
Vol 17 (1) ◽  
pp. 74-81
Author(s):  
Vera V. Galishnikova ◽  
Alireza Heidari ◽  
Paschal C. Chiadighikaobi ◽  
Adegoke Adedapo Muritala ◽  
Dafe Aniekan Emiri
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Basalt Fiber ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Lightweight Aggregate Concrete ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Chopped Basalt Fiber

Relevance. The load on a reinforced concrete slab with high strength lightweight aggregate concrete leads to increased brittleness and contributes to large deflection or flexure of slabs. The addition of fibers to the concrete mix can improve its mechanical properties including flexure, deformation, toughness, ductility, and cracks. The aims of this work are to investigate the flexure and ductility of lightweight expanded clay concrete slabs reinforced with basalt fiber polymers, and to check the effects of basalt fiber mesh on the ductility and flexure. Methods. The ductility and flexural/deflection tests were done on nine engineered cementitious composite (expanded clay concrete) slabs with dimensions length 1500 mm, width 500 mm, thickness 65 mm. These nine slabs are divided in three reinforcement methods types: three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm (first slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed chopped basalt fiber plus basalt fiber polymer (mesh) of cells 2525 mm (second slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed basalt fiber of length 20 mm, diameter 15 m (third slab type). The results obtained showed physical deflection of the three types of slab with cracks. The maximum flexural load for first slab type is 16.2 KN with 8,075 mm deflection, second slab type is 24.7 KN with 17,26 mm deflection and third slab type 3 is 32 KN with 15,29 mm deflection. The ductility of the concrete slab improved with the addition of dispersed chopped basalt fiber and basalt mesh.

scholarly journals Hydrogen-assisted cracking in GMA welding of high-strength structural steels using the modified spray arc process

2020 ◽  
Vol 64 (12) ◽  
pp. 1997-2009
Author(s):  
Thomas Schaupp ◽  
Michael Rhode ◽  
Hamza Yahyaoui ◽  
Thomas Kannengiesser
Keyword(s):  
Weld Metal ◽  
Gma Welding ◽  
High Strength ◽  
Economic Benefits ◽  
Structural Steels ◽  
Test Series ◽  
Deposition Rates ◽  
The Past ◽  
Hydrogen Assisted Cracking ◽  
Implant Test

Abstract High-strength structural steels are used in machine, steel, and crane construction with yield strength up to 960 MPa. However, welding of these steels requires profound knowledge of three factors in terms of avoidance of hydrogen-assisted cracking (HAC): the interaction of microstructure, local stress/strain, and local hydrogen concentration. In addition to the three main factors, the used arc process is also important for the performance of the welded joint. In the past, the conventional transitional arc process (Conv. A) was mainly used for welding of high-strength steel grades. In the past decade, the so-called modified spray arc process (Mod. SA) has been increasingly used for welding production. This modified process enables reduced seam opening angles with increased deposition rates compared with the Conv. A. Economic benefits of using this arc type are a reduction of necessary weld beads and required filler material. In the present study, the susceptibility to HAC in the heat-affected zone (HAZ) of the high-strength structural steel S960QL was investigated with the externally loaded implant test. For that purpose, both Conv. A and Mod. SA were used with same heat input at different deposition rates. Both conducted test series showed same embrittlement index “EI” of 0.21 at diffusible hydrogen concentrations of 1.3 to 1.6 ml/100 g of arc weld metal. The fracture occurred in the HAZ or in the weld metal (WM). However, the test series with Mod. SA showed a significant extension of the time to failure of several hours compared with tests carried out with Conv. A.

scholarly journals Methanogenic Microorganisms in Industrial Wastewater Anaerobic Treatment

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1546
Author(s):  
Monika Vítězová ◽  
Anna Kohoutová ◽  
Tomáš Vítěz ◽  
Nikola Hanišáková ◽  
Ivan Kushkevych
Keyword(s):  
Wastewater Treatment ◽  
Industrial Wastewater ◽  
Methanogenic Archaea ◽  
High Strength ◽  
Anaerobic Treatment ◽  
Microbiome Composition ◽  
Anaerobic Wastewater Treatment ◽  
The Past ◽  
Anaerobic Reactors ◽  
Anaerobic Environment

Over the past decades, anaerobic biotechnology is commonly used for treating high-strength wastewaters from different industries. This biotechnology depends on interactions and co-operation between microorganisms in the anaerobic environment where many pollutants’ transformation to energy-rich biogas occurs. Properties of wastewater vary across industries and significantly affect microbiome composition in the anaerobic reactor. Methanogenic archaea play a crucial role during anaerobic wastewater treatment. The most abundant acetoclastic methanogens in the anaerobic reactors for industrial wastewater treatment are Methanosarcina sp. and Methanotrix sp. Hydrogenotrophic representatives of methanogens presented in the anaerobic reactors are characterized by a wide species diversity. Methanoculleus sp., Methanobacterium sp. and Methanospirillum sp. prevailed in this group. This work summarizes the relation of industrial wastewater composition and methanogen microbial communities present in different reactors treating these wastewaters.

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