Nonlinear Finite Element Analysis Of Shear Failure In Reinforced Concrete Beam-Column Connection

Factors Affecting Shear Failure of Beam-Column Joints

Discuss about the Reinforced Concrete Frame Forms.

Beam-column connection in reinforced concrete frame forms one of the most fundamental aspects of a structure that has a significant role in determining the seismic performance of buildings (Varghese, 2010). Beam-column joints are subjected to shear failure in case the connection is on a moment resisting frame that is under the influence of lateral forces. Such a failure type is not any favorable as it comes with undesirable effects on the seismic performance of the reinforced concrete building especially for the case of moment resisting frames.  Numerous numerical studies have been conducted in the past on reinforced concrete joints through the use of FEM analysis.

An example of such is a numerical examination that was done on the parameters that affect shear failure on exterior joints in non-ductile members (McCormac, 2015). Going by the findings from these numerical analyses, there were two important parameters that were found to be affecting the shear behavior of the joint including the aspect ratio and the ration of the beam longitudinal reinforcement.

In as much as a lot of studies have been indicated on the connections between reinforced beams and columns using various softwares, the main focus of the studies have been on simulating the flexural behavior of the columns add the beams that are adjacent to the joint region. Most of the numerical studies have not been focusing on joint shear behavior of the reinforced concrete connections. This is contrary to the fact that in most cost the shear strength and behavior of joints are in control of the entire responses of the reinforced concrete beam-column connection that are subjected to seismic actions.

Nonlinear finite element analysis of reinforced concrete beam-column connection using joint shear failure as the main failure mode is done using ABAQUS/Standard (Jack, 2015). The behavior of the connections is simulated properly through careful consideration of geometrical and material nonlinearities of the members as well as the failure mode of the joint shear under the influence of seismic loading. The boundary conditions, properties of the materials, geometry, types of elements and nonlinear analysis solution are considered and clearly defined in the pre-processing stage. It became quite of a challenge to finite element simulate the sophisticated behavior of concrete being an anisotropic and non-homogenous material.

The various constitutive models that are used in defining the nonlinear behavior of concrete as a material that is quasi-brittle including the brittle cracking and smeared model, the Concrete Damage Plasticity is chosen and introduced into the numerical model. The main and important elements of the model following the theory of classical plasticity which include flow rule, hardening rule, yield criteria are sufficiently considered in the damage plasticity model. In such a study, the main strategy of the study was numerical modeling of the behavior of reinforced concrete calibrated suing the results from the experiment done by other scholars. The study selected and simulated two reinforced beam-column connections that had both interior and exterior joint configurations (Choo, 2014).

Numerical Analysis of Reinforced Concrete Joints

In the study, the concrete elements were modeled using 3D 8-noded hexahedral elements each having 3 degrees of freedom in each of the nodes in which there was reduced integration so as to prevent the effect of shear locking. 2-nodded truss elements that had 3 degrees of freedom in every node were used in reinforcing the models. Proper simulation is achieved through the adoption of the embedded method that had a perfect bond between the surrounding and the reinforcement (Nawy, 2009). It was noticed that the impacts that normally come with reinforcement-concrete interface including dowel action and bond slip were indirectly modeled through defining tension stiffening into the model of reinforced concrete so as to approximately simulate the transfer of loads across the cracks via the rebar.

GB Codes of China

This refers to a database that contains elaborate and comprehensive coding that is used in the administration of units in China all the way to the county level. These codes are used in the provision of dynamic matrix that is meant for the identification of temporally and spatially specific data that is used in administrative units (Nawy, 2009). The codes are very important when it comes to the mission of CITAS aimed at enhancing the intercomparability of the data of China through offering the required standards for geocoding. The code has undergone developments since the time of their creation. All the GB codes were derived from the formal official coding that are published by the Chinese National Bureau of Standards. In cases in which there are no official codes were to be assigned and noted in effect.

Since the codes are labeled “from” and “to” date, the database managed to offer a continuous and relatively dynamic coverage of the coding that is used for administrative purposes for any given date. This offers the users an opportunity to extract data from a set of codes that belong to a particular dat. Also contained in the database is basic information on the status of the unit that is specific to time such as the name, the prefecture administrative status which bears the county level unit, the coding for the change type that resulted into the unit into its existing status  and county-level unit administrative status (Momber, 2011).

ACI Building Code is a document that offers the code requirements that need to be met for the design and construction of the structural concrete that are needed to achieve the safety of the public. This is a must have standard that is needed by all the professionals who take part in concrete inspecting, design and construction (Choo, 2014). The most current version of the ACI code is the ACI 318 Building Code which a complete reorganization of the previous versions. This new version comes with more charts and tables as well as a consistent flow of the members of each chapter. It also has a few cross references, a chapter that is dedicated to the requirements of construction as well as new chapters on structural systems alongside the accompanying diagrams. By using the new ACI 318-14, a designer or any other professional therefore would be able to identify with surety when his design meets all the relevant provisions of the code.

Nonlinear Finite Element Analysis of Reinforced Concrete Beam-Column Connection

The ACI code offers the minimum requirements for the design, materials as well as detailing of the structural buildings made from concretes and in places where applicable the non-building structures (Toniolo, 2017). Through the code, the structural members, connections and members inclusive of cast-in-place, plain, pre-stressed, composite, precast and non-stressed construction. Among the various subjects covered in the building code are serviceability, durability, load factors, strength for design and construction, deflection limits, field inspection, structural analysis methods as well as other methods that are used in structural analysis.

By referring to the appropriate ASTM standards and specifications, the quality and testing of the materials that are usable in the construction industry are effectively covered. The language and format in which the code is written is such that it permits ease of retrieval and use of the various references without changing the language. This thus eliminates the inclusion of suggestions or background details that are used in conducting the requirements or intention of the provisions of the Code (Varghese, 2010).

Euro code 2: Design of concrete structures is a document that presents the technical rules that should be followed in the design of pre-stressed concrete, concrete and reinforced concrete through the use of the philosophy of limit state design. The document was approved to give the designers an opportunity to practice across the world in any country that accepts the code. The code is intended to be used together with EN 1990, EN 1991, ENV 13670, EN 1997 and EN 1998. The document is divided into various parts Part 1-1 to Part 1-6, Part 2 and then Part 3 with each part exploring on various chapters and subtopics (Bungey, 2012). The parts are as shown:

• Part 1-1 which is about the general rules as well as the rules on building
• Part 1-2 is on structural design for fire
• Part 1-3 talks about the elements and structures of concrete
• Part 1-4 explains lightweight aggregate concrete using closed structure
• Part 1-5 explores the structures with the external and unbounded prestressing tendons
• Part 1-6 is on plain structures of concrete

References

Bungey, J. (2012). Reinforced Concrete Design: to Eurocode 2. New York: Macmillan International Higher Education.

Chaallal, O. (2010). Reinforced Concrete Structures: Design According to CSA A23. 3-04. Sydney: PUQ.

Choo, B. S. (2014). Reinforced Concrete Design to Eurocodes: Design Theory and Examples, Fourth Edition. Oxford: CRC Press.

Hellesland, J. (2013). Reinforced Concrete Beams, Columns and Frames: Mechanics and Design. Moscow: John Wiley & Sons.

Jack, M. (2015). Design of Reinforced Concrete, 10th Edition. Kansas: Wiley.

McCormac, J. C. (2015). Design of Reinforced Concrete, 10th Edition. London: Wiley.

Momber, A. (2011). Hydrodemolition of Concrete Surfaces and Reinforced Concrete. London: Elsevier.

Nawy, E. G. (2009). Reinforced Concrete: A Fundamental Approach. New York: Prentice Hall.

Toniolo, G. (2017). Reinforced Concrete Design to Eurocode 2. New York: Springer.

Varghese, P. (2010). Design of Reinforced Concrete Shells and Folded Plates. London: PHI Learning Pvt. Ltd.