Ground penetrating radar for the evaluation of reinforced concrete structures

The evaluation and inspection of steel bars in reinforced concrete structures are critical for prolonging the service life of buildings. In this regard, ground-penetrating radar (GPR) has been a crucial alternative due to its non-invasiveness and convenience. This paper reports the experimental activities on a test-site area inside a camp in Shanghai, China. To assess the concrete structures of the building, GPR was employed for the detection and localization of rebars in columns, beams, and floors. From the GPR B-scan profiles acquired using a high-frequency antenna, the exact quantity of reinforcements was identified according to the hyperbola responses. Considering the difficulty of inferring the exact position and the scale of the rebars, we applied reverse time migration (RTM) to collapse the hyperbolic response and retrieve the target in a migrated image. To verify the effectiveness of the RTM algorithm, we carried out an experiment on a concrete model with three reinforced bars. We also utilized the RTM algorithm to process the B-scan profiles collected in a column that was later excavated. The imaging results validated the capacity of RTM in localizing and shaping rebars. Then, we employed the RTM algorithm for the GPR B-scan data collected from the other column. Based on the imaging profile, the quantity and positions of the rebars were correctly determined. Moreover, the thickness of the protective layer was evaluated according to the migrated result. These results demonstrate that GPR combined with RTM could provide useful foundation data for structural evaluation.

Download Full-text

Non-Destructive Corrosion Inspection of Reinforced Concrete Using Ground-Penetrating Radar: A Review

Materials ◽

10.3390/ma14040975 ◽

2021 ◽

Vol 14 (4) ◽

pp. 975

Author(s):

Ksenija Tešić ◽

Ana Baričević ◽

Marijana Serdar

Keyword(s):

Reinforced Concrete ◽

Ground Penetrating Radar ◽

Concrete Structures ◽

Condition Assessment ◽

Concrete Cover ◽

Corrosion Process ◽

Laboratory Studies ◽

Corrosion Assessment ◽

Ground Penetrating ◽

Non Destructive

Reduced maintenance costs of concrete structures can be ensured by efficient and comprehensive condition assessment. Ground-penetrating radar (GPR) has been widely used in the condition assessment of reinforced concrete structures and it provides completely non-destructive results in real-time. It is mainly used for locating reinforcement and determining concrete cover thickness. More recently, research has focused on the possibility of using GPR for reinforcement corrosion assessment. In this paper, an overview of the application of GPR in corrosion assessment of concrete is presented. A literature search and study selection methodology were used to identify the relevant studies. First, the laboratory studies are shown. After that, the studies for the application on real structures are presented. The results have shown that the laboratory studies have not fully illuminated the influence of the corrosion process on the GPR signal. Also, no clear relationship was reported between the results of the laboratory studies and the on-site inspection. Although the GPR has a long history in the condition assessment of structures, it needs more laboratory investigations to clarify the influence of the corrosion process on the GPR signal.

Download Full-text

Design of precast reinforced concrete structures of frame buildings: a new set of rules

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.04.04-09 ◽

2019 ◽

pp. 4-9 ◽

Cited By ~ 1

Keyword(s):

Reinforced Concrete ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Building Frames ◽

Fine Grained ◽

Rigid Frame ◽

Floor Slabs ◽

Frame Buildings ◽

Spatial System ◽

Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

Download Full-text

Improvement Of Curvilinear Diagrams Of Concrete Deformation

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.08.99-104 ◽

2019 ◽

pp. 99-104

Keyword(s):

Reinforced Concrete ◽

Peak Load ◽

Experimental Studies ◽

Concrete Structures ◽

Deformation Model ◽

Reinforced Concrete Structures ◽

Significant Difference ◽

Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Download Full-text