scholarly journals Mechanical Performance and Chloride Diffusivity of Cracked RC Specimens Exposed to Freeze-Thaw Cycles and Intermittent Immersion in Seawater

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Bei Shen ◽  
Yinghua Ye ◽  
Bo Diao ◽  
Xiaoning Zheng
Keyword(s):  
Crack Width ◽  
Ultimate Load ◽  
Mechanical Performance ◽  
Exposure Period ◽  
Chloride Ingress ◽  
Rc Structures ◽  
Yield Load ◽  
Compression Load ◽  
Freeze Thaw ◽  
Deicing Salts

The effects of crack width on chloride ingress and mechanical behavior of reinforced concrete (RC) specimens were experimentally studied after exposure to 300 cycles of freeze-thaw and seawater immersion (75 times). Cracks were induced prior to exposure by an eccentric compression load which was sustained until the end of the exposure period. The maximum cracks widths induced in the four column specimens were 0, 0.06, 0.11, and 0.15 mm, respectively. Results show that when the crack width was less than 0.06 mm, the effect of cracks on chloride ingress could be neglected. However, when the crack width was more than 0.11 mm, chloride ingress was accelerated. Results of static loading tests show that both yield load and ultimate load of RC columns decreased as crack width increased. When the crack width was 0.15 mm, yield load and ultimate load of RC column specimen decreased by 17.0% and 18.9%, respectively, compared to a specimen without cracks. It was concluded that crack width significantly promoted local chloride ingress and mechanical performance degradation of RC structures in cold coastal regions or exposed to deicing salts.

scholarly journals Impact of Cyclic Loading on Chloride Diffusivity and Mechanical Performance of RC Beams under Seawater Corrosion

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Sen Pang ◽  
Bo Diao ◽  
Yinghua Ye ◽  
Shuxin Chen ◽  
Xin Wang
Keyword(s):  
Cyclic Loading ◽  
Crack Width ◽  
Steel Surface ◽  
Ultimate Load ◽  
Mechanical Performance ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Rc Beams ◽  
Chloride Diffusivity

An experimental study was conducted to investigate the impact of cyclic loading on the mechanical performance and chloride diffusivity of RC beams exposed to seawater wet-dry cycles. To induce initial damage to RC beam specimen, cyclic loading controlled by max load and cycles was applied. Then beam specimens underwent 240 wet-dry cycles of seawater. Results show that the chloride content increased as max load and cycle increased. The chloride content at steel surface increased approximatively linearly as average crack width increased. Moreover, the max load had more influence on chloride content at steel surface than cycle. The difference of average chloride diffusion coefficient between tension and compression concrete was little at uncracked position. Average chloride diffusion coefficient increased as crack width increased when crack width was less than 0.11 mm whereas the increasing tendency was weak when crack width exceeded 0.11 mm. The residual yield load and ultimate load of RC beams decreased as max load and cycle increased. Based on univariate analysis of variance, the max load had more adverse effect on yield load and ultimate load than cycle.

scholarly journals Experimental investigation on composite beams under combined negative bending and torsional moments

2020 ◽  
pp. 136943322098166
Author(s):  
Weiwei Lin
Keyword(s):  
Ultimate Load ◽  
Mechanical Performance ◽  
Composite Beams ◽  
Strain Development ◽  
Shear Connectors ◽  
Load Carrying ◽  
Interface Slip ◽  
Negative Bending ◽  
Support Conditions ◽  
Main Girder

In this study, straight composite steel-concrete beams were tested to investigate their mechanical performance under combined negative bending and torsional moments. Two specimens were used in this study, and different ratios between the applied negative bending and torsional moments were induced. Load and deflection relationships, strain development on the steel main girder and shear connectors (stud), and the slip development on the steel-concrete interface were recorded in the test and reported in this paper. The results indicate that increase of torsional moment will result in the significant decrease of the load-carrying capacities (e.g. yield load and ultimate load) of the specimens. It was also found that the normal strains of stud shear connectors in such beams are very large and non-negligible compared to their shear strains. In addition, the maximum interface slip was found occurring at around the 1/4 span, and the support conditions and serious crack of the concrete were considered to be the main causes. The research results obtained in this study can provide references for the design and analysis of steel-concrete composite beams subjected to the combined negative bending and torsional moments.

Effect of Axial Compression Ratio on Ductility and Bearing Capacity of Specially Shaped Columns with HRB500 Reinforcement

2012 ◽  
Vol 204-208 ◽  
pp. 1066-1069
Author(s):  
Yan Jun Li ◽  
Ping Liu
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Compression Ratio ◽  
Ultimate Load ◽  
Deformation Capacity ◽  
Displacement Ductility ◽  
Yield Load ◽  
Axial Compression Ratio ◽  
Low Cyclic Loading ◽  
Specially Shaped Column

Four specially shaped columns with HRB500 reinforcement were tested under low cyclic loading. The hysteretic curve, yield load, ultimate load, displacement ductility and rigidity degradation were compared in order to research the effect of axial compression ratio on ductility and bearing capacity of specially shaped column with HRB500 reinforcement. It is shown that the axial compression ratio has greater influence on ductility and bearing capacity. With the increase of axial compression ratio, the bearing capacity of HRB500 reinforcement concrete specially shaped column can be enhanced while the deformation capacity becomes worse. The hysteretic characteristic of specially shaped columns with HRB500 reinforcement is improved and the stiffness degeneration becomes slow with the decrease of axial compression ratio.

Damage of Reinforced Concrete Structures due to Steel Corrosion

2015 ◽  
Vol 1111 ◽  
pp. 187-192
Author(s):  
Corina Sosdean ◽  
Liviu Marsavina ◽  
Geert de Schutter
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Structural Integrity ◽  
Colorimetric Method ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Degradation Process ◽  
Reinforced Concrete Structures ◽  
Chloride Ingress ◽  
Rc Structures

Reinforced concrete (RC) became one of the most widely used modern building materials. In the last decades a great interest has been shown in studying reinforcement corrosion as it became one of the main factors of degradation and loss of structural integrity of RC structures. The degradation process is accelerated in the case of RC structures situated in aggressive environments like marine environments or subjected to de-icing salts. In this paper it is shown how steel corrosion of the embedded rebars occurs and how this affects the service life of reinforced concrete structures. Also, an experimental study regarding the combined effect of carbonation and chloride ingress was realized. Samples with and without rebars were drilled from a RC slab which was stored in the laboratory for two years. Non-steady state migration tests were realized in order to determine the chloride profile, while the carbonation depth was measured using the colorimetric method based on phenolphthalein spraying. It was concluded that carbonation has a significant effect on chloride ingress, increasing it.

Short-term behaviour of reinforced and steel fibre–reinforced concrete composite slabs with steel decking under negative bending moment

2017 ◽  
Vol 21 (9) ◽  
pp. 1288-1301 ◽  
Author(s):  
Alireza Gholamhoseini ◽  
Amir Khanlou ◽  
Gregory MacRae ◽  
Stephen Hicks ◽  
Allan Scott ◽  
...  
Keyword(s):  
Crack Width ◽  
Ultimate Load ◽  
Steel Fibre ◽  
Bending Moment ◽  
Fibre Reinforced Concrete ◽  
Short Term ◽  
Crack Control ◽  
Steel Fibre Reinforced Concrete ◽  
Composite Slabs ◽  
Negative Bending

An experimental study was conducted on reinforced and steel fibre–reinforced concrete composite slabs with steel decking under negative bending moment to quantify the ultimate behaviour, loading capacity and crack width under short-term loading. Eight full-scale slab specimens were cast with different types and amounts of reinforcement in the concrete (e.g. mesh, steel fibre or normal reinforcing bars) but with the same type of steel decking. Each slab was simply supported and tested in four-point bending under increasing load until failure. The deflections at mid-span and under the applied point loads were monitored together with the end interface slip. The crack widths were obtained for each slab for different levels of applied load. It was found that the end slip was quite negligible and complete interaction on the steel decking–concrete slab interface existed at service loads and ultimate limit states. Compared to the slab with 20 kg/m3 steel fibre, the application of steel fibre in excess of 60 kg/m3 increased the rotational capacity and ultimate load by 60% and 80%, respectively. Moreover, the higher dosage of steel fibres resulted in improved crack control, as for the same level of applied load, the crack width was often reduced by 75%. However, the slabs with conventional high-strength ductile reinforcements had the greatest ultimate load and rotational capacity and exhibited the best degree of crack control with finer and more distributed cracks.

scholarly journals The use of approximate methods of seismic assessment of structures

2018 ◽  
Vol 188 ◽  
pp. 03010
Author(s):  
Maria Basdeki ◽  
Argyro Drakakaki ◽  
Charis Apostolopoulos
Keyword(s):  
Seismic Performance ◽  
Mechanical Performance ◽  
Corrosion Damage ◽  
Masonry Structures ◽  
Seismic Evaluation ◽  
Approximate Methods ◽  
Rc Structures ◽  
Existing Structures ◽  
Corrosion Factor ◽  
Masonry Tower

Greece is an earthquake prone area, which is also exposed to coastal environment. Most existing buildings present common characteristics, concerning quality of the materials and environmental conditions [1].The vulnerability of these structures is exteriorized under powerful seismic loads. This is because they were designed, according to older regulations, primarily to bear vertical loads and secondarily to bear horizontal loads, an indicative sign of the absence of anti-seismic design. Designing and evaluation of the seismic performance of existing structures is a really complex issue, because structural degradation phenomenon is related to both corrosion damage of steel reinforcement on RC structures and high vulnerability of masonry. Precisely, the inadequate seismic performance of masonry structures, which is recorded under intense earthquakes, is attributed to the characteristics of masonry and to the ageing phenomena of the materials. For the seismic inspection of masonry structures, both EC2 and OASP can be used [3], although there is often a great misunderstanding concerning the range of the maximum permissible interventions, the financial inability and modern perceptions of redesigning [2]. On the other hand, in the case of RC structures, there is no prediction –concerning the corrosion factor- included in the international regulations and standards. In the current study is presented an experimental procedure, concerning a RC column before and after corrosion. An estimation concerning the drop of its mechanical performance has taken place, indicating the importance of the corrosion factor. Additionally, an existing monumental masonry tower building, was subjected to seismic evaluation [4]. Both OASP and EC2 inspection methods were used. The results pointed out that, for medium–intensity earthquakes, both analytical and approximate methods are respectable and reliable.

scholarly journals Experimental Study on Corrosion and Mechanical Behavior of Main Cable Wires Considering the Effect of Strain

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 753 ◽  
Author(s):  
Fangyuan Xu ◽  
Yuanli Chen ◽  
Xianglong Zheng ◽  
Rujin Ma ◽  
Hao Tian
Keyword(s):  
Elastic Modulus ◽  
Mass Loss ◽  
Stress Level ◽  
Corrosion Test ◽  
Ultimate Load ◽  
Cross Sectional ◽  
Accelerated Corrosion ◽  
Yield Load ◽  
Accelerated Corrosion Test ◽  
Corrosion Time

To study the corrosion degradation of cable wires in a bridge’s life, this research work created an accelerated corrosion test device, which sought to identify an optimal constant strain level. An accelerated corrosion test was carried out and the corroded specimens were scanned using super depth 3D microscopy technology. Mass loss and minimum cross-sectional diameter was measured to understand the degradation characteristics of cable wires at variable strains and corrosion time. The variation of elastic modulus, yield load, and ultimate load of corroded wires, subjected to a tensile test, were analyzed. The experimental results illustrate that the average mass loss ratio of the corroded cable wires increases nonlinearly as corrosion time increases. The higher the stress level, the more serious the corrosion level. The minimum cross-sectional diameter has good correlation with corrosion time and stress level. The elastic modulus of wires does not change significantly with the increase of corrosion time. Yield load and ultimate load decreases with the increase of strain level, and the rates of decline under different strains are nonlinear.

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