Civil Engineering and Architecture Vol. 10(4), pp. 1385 - 1404
DOI: 10.13189/cea.2022.100412
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Computation of Natural Frequencies of Masonry Infilled RC Frames Validated with Modal Assurance Criterion


Achutha Herur Gopalaiah *, Chethan K.
Department of Civil Engineering, University Visvesvaraya College of Engineering (UVCE), Bengaluru – 560056, India

ABSTRACT

Contribution of infill walls to in-plane structural response of reinforced concrete (RC) frame is an important aspect that many researchers have studied using experimental and numerical methods. This paper presents the modeling of 3D RC unreinforced masonry infill (MI) frames using multiple nodes to one node constraint (MTOCO) with the independent node at the center of gravity of infill with mass and inertial properties of infill. This method of modeling is then compared with other macro and micro modeling methods. A macro model with equivalent diagonal strut using 1D element and two micro models, both with 8-noded brick elements with the interface between infill and RC frame modeled using node to surface tied interface in one and small sliding contact in another. All these four models are solved using a Virtual Performance Solution (VPS) implicit FE solver. Natural frequencies of the structure from these four numerical solutions are then compared with available experimental shake table [25] results. To assess the degree of consistency between the four numerical methods, Modal Assurance Criterion (MAC) [29] is used. The Modal Assurance Criterion is a statistical indicator that is most sensitive to large differences and relatively insensitive to small differences in the mode shapes. This yields a good statistical indicator and a degree of consistency between mode shapes. From a functional point of view, the openings in the infills are a significant parameter to consider because they influence the lateral stiffness and strength. Having established its validity as explained above, this new methodology is then extended to RC frames with openings and partial fillings. A comparison of the results of both micro and macro methods shows a very good correlation.

KEYWORDS
Diagonal Strut, Modal Assurance Criterion, Multi to One Nodal Constraint, Unreinforced Masonry, Virtual Performance Solution

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Achutha Herur Gopalaiah , Chethan K. , "Computation of Natural Frequencies of Masonry Infilled RC Frames Validated with Modal Assurance Criterion," Civil Engineering and Architecture, Vol. 10, No. 4, pp. 1385 - 1404, 2022. DOI: 10.13189/cea.2022.100412.

(b). APA Format:
Achutha Herur Gopalaiah , Chethan K. (2022). Computation of Natural Frequencies of Masonry Infilled RC Frames Validated with Modal Assurance Criterion. Civil Engineering and Architecture, 10(4), 1385 - 1404. DOI: 10.13189/cea.2022.100412.