Field Instrumentation of Concrete Structures

2009 ◽  
pp. 63-63-15 ◽  
Author(s):  
HG Russell
Keyword(s):  
Concrete Structures ◽  
Field Instrumentation

Distributed Optical-fibre Strain Sensing in Reinforced Concrete Structures

2015 ◽  
Vol 74 (4) ◽  
Author(s):  
Hisham Mohamad ◽  
Ahmad Beng Hong Kueh ◽  
Ahmad Safuan A Rashid
Keyword(s):  
Optical Fibre ◽  
Best Practice ◽  
Concrete Structures ◽  
Time Domain Reflectometry ◽  
Strain Sensing ◽  
Field Instrumentation ◽  
Optical Time Domain Reflectometry ◽  
Fibre Strain ◽  
Load Tests ◽  
Optical Time

An innovative technique based on optical fibre sensing that allows continuous strain measurement has recently been introduced in structural health monitoring. Known as Brillouin Optical Time-Domain Reflectometry (BOTDR), this distributed sensing technique allows measurement of strain along the full length (up to 10 km) of a suitably installed optical fibre. The sensors can be wrapped around or embedded in structures, where a single optical fibre potentially replaces a very large number of point sensors. The installation of optical fibres in concrete structures involved several procedures such as pre-tensioning of cables, spot-glued or end-clamped onto steel rebars, and the use different types of commercially available optical cables. Such instrumentation techniques must be validated in terms of their measurement performance, which is the aim of this research. This was done through a series of well-instrumented uniaxial load tests of concrete columns. The loading of the structures were performed within the elastic range and later loaded up to failure. The test results revealed that all sensing cables of various types used in this study measured strains of about the same values (within the BOTDR accuracy of 30 microstrains) and were comparable with other independent instrumentation devices. Strain data from the two methods of attachment (spot-glued or end-clamped), either pre-tension or without pre-strain, generally did not indicate any dissimilarity between them. These findings have enabled the establishment of the best practice of field instrumentation consisting fibre optic sensors in the current exploration the use of end-clamping technique.

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

2019 ◽  
pp. 4-9 ◽  
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.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

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.

A Study of Rehabilitation of Exisisting Concrete Structures

2012 ◽  
Vol 3 (4) ◽  
pp. 79-81
Author(s):  
Prof. Y. R. Suryavanshi Prof. Y. R. Suryavanshi ◽  
◽  
Vardan Chandnani ◽  
Prasad Dhumal ◽  
Sohabran Singh Pundir ◽  
...  
Keyword(s):  
Concrete Structures
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