scholarly journals Self-consolidating concrete : rheology, fresh properties and structural behaviour

2021 ◽  
Author(s):  
Vasilios Bill Lambros
Keyword(s):  
Load Capacity ◽  
Low Cost ◽  
Peak Load ◽  
Aggregate Size ◽  
Steel Tube ◽  
Reinforced Concrete Beams ◽  
Maximum Aggregate Size ◽  
Fresh Properties ◽  
Structural Behaviour ◽  
Self Consolidating Concrete

Self-consolidating concrete (SCC) is known for its excellent deformability, high resistance to segregation and bleeding and can be obtained by incorporating viscosity modifying agents (VMA). Identifying and proposing a new low-cost VMA, and developing and testing the fresh and mechanical properties of such a concrete are essential. This thesis presents the performance of four new polysaccharide-based VMAs in enhancing the rheological and fresh properties of cement paste, mortar and concrete. An experimental study on the structural properties of two SCC and one normal concrete (NC) mixtures with varying proportions of coarse aggregate content (713-1030 kg/m 3 ) and maximum aggregate size (12 and 19-mm) is presented. Eighteen reinforced concrete beams were tested to study the comparative shear resistance of SCC and NC. Sixteen SCC and NC filled steel tube columns with and without additional steel reinforcement were tested. A design equation for peak load capacity of CFST columns is proposed and validated.

scholarly journals Self-consolidating concrete : rheology, fresh properties and structural behaviour

2021 ◽  
Author(s):  
Vasilios Bill Lambros
Keyword(s):  
Load Capacity ◽  
Low Cost ◽  
Peak Load ◽  
Aggregate Size ◽  
Steel Tube ◽  
Reinforced Concrete Beams ◽  
Maximum Aggregate Size ◽  
Fresh Properties ◽  
Structural Behaviour ◽  
Self Consolidating Concrete

Self-consolidating concrete (SCC) is known for its excellent deformability, high resistance to segregation and bleeding and can be obtained by incorporating viscosity modifying agents (VMA). Identifying and proposing a new low-cost VMA, and developing and testing the fresh and mechanical properties of such a concrete are essential. This thesis presents the performance of four new polysaccharide-based VMAs in enhancing the rheological and fresh properties of cement paste, mortar and concrete. An experimental study on the structural properties of two SCC and one normal concrete (NC) mixtures with varying proportions of coarse aggregate content (713-1030 kg/m 3 ) and maximum aggregate size (12 and 19-mm) is presented. Eighteen reinforced concrete beams were tested to study the comparative shear resistance of SCC and NC. Sixteen SCC and NC filled steel tube columns with and without additional steel reinforcement were tested. A design equation for peak load capacity of CFST columns is proposed and validated.

The rate effect on fracture mechanics of dam concrete based on DIC and AE techniques

2021 ◽  
pp. 030932472110381
Author(s):  
Jingwu Bu ◽  
Xinyu Wu ◽  
Huiying Xu ◽  
Xudong Chen
Keyword(s):  
Acoustic Emission ◽  
Fracture Mechanics ◽  
Loading Rate ◽  
Boundary Effect ◽  
Peak Load ◽  
Aggregate Size ◽  
Image Correlation ◽  
Maximum Aggregate Size ◽  
Test Results ◽  
Dam Concrete

In order to study the effect of loading rate on fracture behavior of dam concrete, wedge splitting tests of various loading rates (0.1, 0.01, and 0.001 mm/s) are carried out on two kinds of full-graded dam concrete notched cubes with side lengths of 300 and 450 mm, respectively. Digital image correlation and acoustic emission technique are used to measure the deformation and acoustic emission parameters of the dam concrete. Test results show that: the peak load and fracture energy of dam concrete specimens increases with the increase of loading rate. And the higher the loading rate is, the fracture of concrete shows more obvious brittleness. Influenced by the boundary effect, the CTOD increases with the increasing of loading rate, however, the length of crack decreases as loading rate increases. With the loading rate increases, the energy mutation area is more obvious, while the accumulated acoustic emission energy is affected by both the loading rate and the maximum aggregate size. The number of acoustic emission three-dimensional locating points and the shear signal decrease with the increase of loading rate, which is attributed to that the faster the loading rate is, the less sufficient the development of micro cracks in concrete is. The test results can supply experimental data to the fracture mechanics of dam concrete.

Flexural behavior of fire-damaged reinforced concrete beams repaired with high-strength fiber reinforced mortar

2019 ◽  
Vol 10 (1) ◽  
pp. 56-75 ◽  
Author(s):  
Muhd Afiq Hizami Abdullah ◽  
Mohd Zulham Affandi Mohd Zahid ◽  
Afizah Ayob ◽  
Khairunnisa Muhamad
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Load Capacity ◽  
Peak Load ◽  
High Strength ◽  
Elastic Stiffness ◽  
Reinforced Concrete Beams ◽  
Repair Material ◽  
Content Type ◽  
High Strength Fiber

Purpose The purpose of this study is to investigate the effect on flexural strength of fire-damaged concrete repaired with high-strength mortar (HSM). Design/methodology/approach Reinforced concrete beams with dimension of 100 mm × 100 mm × 500 mm were used in this study. Beams were then heated to 400°C and overlaid with either HSM or high-strength fiber reinforced mortar (HSFM) to measure the effectiveness of repair material. Repaired beams of different material were then tested for flexural strength. Another group of beams was also repaired and tested by the same procedure but was heated at higher temperature of 600°C. Findings Repair of 400°C fire-damaged samples using HSM regained 72 per cent of its original flexural strength, 100.8 per cent of its original toughness and 56.9 per cent of its original elastic stiffness. Repair of 400°C fire-damaged samples using HSFM regained 113.5 per cent of its original flexural strength, 113 per cent of its original toughness and 85.1 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSM regained 18.7 per cent of its original flexural strength, 25.9 per cent of its original peak load capacity, 26.1 per cent of its original toughness and 22 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSFM regained 68.4 per cent of its original flexural strength, 96.5 per cent of its original peak load capacity, 71.2 per cent of its original toughness and 52.2 per cent of its original elastic stiffness. Research limitations/implications This research is limited to the size of the furnace. The beam specimen is limited to 500 mm of length and overall dimensions. This dimension is not practical in actual structure, hence it may cause exaggeration of deteriorating effect of heating on reinforced concrete beam. Practical implications This study may promote more investigation of using HSM as repair material for fire-damaged concrete. This will lead to real-world application and practical solution for fire-damaged structure. Social implications The aim of this research in using HSM mostly due to the material’s high workability which will ease its application and promote quality in repair of damaged structure. Originality/value There is a dearth of research on using HSM as repair material for fire-damaged concrete. Some research has been carried out using mortar but at lower strength compared to this research.

scholarly journals Effect of filling steel tube chords by concrete on the structural behaviour of composite truss girders

2020 ◽  
Vol 13 (3) ◽  
pp. 167-174
Author(s):  
Kareem Mohamed Alnebhan ◽  
Muhaned A. Shallal
Keyword(s):  
Failure Modes ◽  
Ultimate Load ◽  
Concrete Slab ◽  
Load Capacity ◽  
Steel Tube ◽  
Structural Behaviour ◽  
Steel Tubes ◽  
Surface Plasticity ◽  
Concrete Deck ◽  
Monotonic Load

In this study, three specimens of Warren truss girders composite with concrete deck slab were tested experimentally under a central monotonic load to study the effect of the existence of concrete inside the chords. The load capacity, deflection, slip between the concrete slab and steel tube, and failure modes were reported. Both chords were filled with concrete to the first specimen, only the lower chord was filled with concrete and the upper chord remained hollow to the second specimen and both chords were kept hollow in the third specimen. The result indicated that the existence of concrete inside the chords has a significant effect on the load capacity, failure pattern, and the slip. The steel tubes of the upper chord filled by concrete prevent surface plasticity failure of the upper chord under loading and increase the ultimate load by 6.68 %. Also, filling the lower chord with concrete prevents the surface plasticity failure in the supports zone and caused an increase in the ultimate load by 39.59 %. The slip at the end of the specimen of two chords filled with concrete is less by 71% than the end slip of specimen of hollow top chord and higher by 46.8 % than the specimen of two hollow chords.

scholarly journals UHPC SANDWICH STRUCTURES WITH COMPOSITE COATING UNDER COMPRESSIVE LOAD

2016 ◽  
Vol 7 ◽  
pp. 38
Author(s):  
Jan Markowski ◽  
Ludger Lohaus
Keyword(s):  
Composite Coating ◽  
High Performance Concrete ◽  
Sandwich Structures ◽  
Load Capacity ◽  
Weight Ratio ◽  
Steel Tube ◽  
Structural Behaviour ◽  
Dead Weight ◽  
Concrete Core ◽  
Load Bearing

Ultra-high-performance concrete (UHPC) sandwich structures with composite coating serve as multipurpose load-bearing elements. The UHPC’s extraordinary compressive strength is used in a multi-material construction element, while issues regarding the concrete’s brittle failure behaviour are properly addressed. A hollow section concrete core is covered by two steel tubes. The outer steel tube is wrapped in a composite material. By this design, UHPC is used in a material- and shape-optimised way with a low dead weight ratio[1] concerning the load-bearing capacity and stability[2]. The cross-section’s hollow shape optimises the construction’s buckling stability while saving self-weight. The composite coating on the column’s outside functions both as a layer increasing the construction’s durability and as a structural component increasing the the maximum and the residual load capacity. Investigations on the construction’s structural behaviour were performed.

scholarly journals The Effects of Maximum Attapulgite Aggregate Size and Steel Fibers Content on Fresh and Some Mechanical Properties of Lightweight Self Compacting Concrete

2020 ◽  
Vol 26 (5) ◽  
pp. 172-190
Author(s):  
Shubbar Jawad Al-obaidey
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Aggregate Size ◽  
Steel Fibers ◽  
Maximum Aggregate Size ◽  
Marginal Effect ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Flexural Tensile Strength

The main objectives of this study were investigating the effects of the maximum size of coarse Attapulgite aggregate and micro steel fiber content on fresh and some mechanical properties of steel fibers reinforced lightweight self-compacting concrete (SFLWSCC). Two series of mixes were used depending on maximum aggregate size (12.5 and 19) mm, for each series three different steel fibers content were used (0.5 %, 1%, and 1.5%). To evaluate the fresh properties, tests of slump flow, T500 mm, V funnel time, and J ring were carried out. Tests of compressive strength, splitting tensile strength, flexural tensile strength, and calculated equilibrium density were done to evaluate mechanical properties. For reference mixes, the results showed that mixes with a larger maximum aggregate size of 19 mm exhibited better fresh properties, while mechanical properties negatively affected by using a larger maximum aggregate size. The results also showed that using steel fibers led to negative effects on fresh properties, especially with higher steel fibers content and larger maximum aggregate size. The marginal effect of steel fibers on compressive strength was noticed, while for both splitting and flexural tensile strength, significant increase was obtained with increasing of steel fibers content. The properties of SFLWSCC in the fresh state had a considerable effect on mechanical properties, whereas with the best fresh properties, the best mechanical properties can be obtained.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

Using Large Linked Field Data Sets to Investigate Density’s Impact on the Performance of Washington State Department of Transportation Asphalt Pavements

2021 ◽  
pp. 036119812110061
Author(s):  
Ryan Howell ◽  
Stephen Muench ◽  
Milad Zokaei Ashtiani ◽  
James Feracor ◽  
Mark Russell ◽  
...  
Keyword(s):  
Aggregate Size ◽  
Large Data ◽  
State Department ◽  
Washington State ◽  
Maximum Aggregate Size ◽  
Test Case ◽  
Data Sets ◽  
Department Of Transportation ◽  
Clear Trend ◽  
Washington State Department

Large data sets of Washington State Department of Transportation (WSDOT) pavement construction and condition data are linked together and used to investigate an implemented change in in-place density to lower specification limit (LSL) from 91% to 92%. This serves as a test case for using such large in-service data sets to create analysis value for a state DOT. Findings include: (1) WSDOT field density has remained relatively steady at 93% for over 20 years; (2) raising the density LSL to 92% will likely result in more contractor effort to achieve higher densities; (3) no clear trend links density with better pavement condition; (4) raising the density LSL will likely result in fewer problematically low densities; and (5) there is no evidence of differing pavement performance based on asphalt content, gradation, or nominal maximum aggregate size.

Experiment Study on Cyclic Behavior of Concrete Filled Steel Tube (CFST) Column-Reinforced Concrete (RC) Beam Connections

2009 ◽  
Vol 417-418 ◽  
pp. 833-836 ◽  
Author(s):  
Qing Xiang Wang ◽  
Shi Run Liu
Keyword(s):  
Reinforced Concrete ◽  
Tube Wall ◽  
Plastic Hinge ◽  
Steel Tube ◽  
Reinforced Concrete Beams ◽  
Cyclic Behavior ◽  
Concrete Core ◽  
Concrete Filled Steel Tube ◽  
Steel Bars ◽  
Moment Resisting

The test results of six connections under cyclic loading are presented in the paper. Each test specimen was properly designed to model the interior joint of a moment resisting frame, and was identically comprised of three parts that including the circular concrete filled steel tube columns, the reinforced concrete beams, and the short fabricated connection stubs. Energy dissipation was designed to occur in the beams during a severe earthquake. Steel bars which were embedded into concrete core and welded to the connection stubs, were used to transfer the force distributed by the reinforcing bars of concrete beam to the concrete core. The results indicated that the embedded steel bars were very efficient in eliminating the stress concentration on the tube wall and there was no visible deformation occurred on the tube wall until the collapse of the specimen. Furthermore, the connection of each specimen had enough capacity and thus the plastic hinge appeared in the beams. As results, the ductility of this new type structure directly depended on the RC beams.

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