@conference {691, title = {Properties of RC walls produced by infilling a frame with concrete for seismic rehabilitation}, booktitle = {SMAR-2015 3rd Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures }, year = {2015}, address = {Antalya, Turkey}, abstract = {

In seismic retrofitting of concrete buildings, frame bays are converted to reinforced concrete (RC) walls by infilling the space between the frame members with RC of a thickness of not more than their width. The cyclic behavior of the resulting wall depends on the connection between the RC infill and the surrounding RC members. The paper uses results from 48 cyclic tests of such composite walls to express their properties in terms of the geometry, the reinforcement and the connection. Properties addressed are: a) the yield moment at the story base; b) the secant-to-yield-point stiffness over the shear span of the wall in a story; c) the deflection at flexural failure in cyclic loading; d) the cyclic shear resistance, including sliding shear. Separate models are given for squat walls failing in shear. The models are modifications of the ones developed in the past for monolithic RC walls from several hundred cyclic tests.

}, author = {Biskinis, D and Psaros-Andriopoulos, A and Fardis, MN} } @article {690, title = {Strength, deformation capacity and failure modes of RC walls under cyclic loading}, journal = {Bulletin of Earthquake Engineering}, year = {2015}, abstract = {

Past models for the cyclic strength and deformation capacity of reinforced concrete walls are evaluated and new ones are developed using results from 866 wall tests. On the basis of the observed damage, the failure mode is classified into the following categories: in flexure, in diagonal tension, in diagonal compression, or in sliding shear. Among the past models evaluated are those proposed by two of the authors: (a) for the cyclic strength in diagonal tension after flexural yielding or in diagonal compression and (b) for the ultimate chord rotation capacity under cyclic flexure, which were adopted in Eurocode 8-Part 3 and in fib Model Code 2010. Walls with height-to-length ratio\1.2 ({\textquoteleft}{\textquoteleft}squat{\textquoteright}{\textquoteright}) are considered separately: past models are evaluated and two new ones are proposed on the basis of 321 cyclic tests. Past models for sliding shear strength are modified, using the results from 55 cyclic tests. The predictions for the failure mode and the cyclic strength and/or deformation capacity agree well with the tests.

}, keywords = {Concrete walls, Cyclic loading, Deformation capacity, Ductility, Eurocode 8, RC walls, Seismic assessment, Seismic design, Seismic evaluation, Shear strength, Ultimate deformation}, doi = {10.1007/s10518-015-9762-x}, url = {http://link.springer.com/article/10.1007/s10518-015-9762-x}, author = {Grammatikou, S and Biskinis, D and Fardis, MN} } @conference {686, title = {RC members in cyclic loading: strength, deformation capacity, failure modes}, booktitle = {8th International Conference on Analytical Models and New Concepts in Concrete and Masonry Structures AMCM 2014}, year = {2014}, address = {Wroc{\l}aw, Poland}, abstract = {

A portfolio of simple, practical models is presented for a) the resistance of a RC member in flexure or shear under cyclic loading; b) its deformation at flexural yielding and its secant-to-yield-point stiffness; and c) the member ultimate deformation in flexure or shear under cyclic loading. They are based on a databank of several thousand tests of RC members - the largest in the world. They cover beams, rectangular columns or walls, members with circular, T-, H-, U- or hollow rectangular section, with or without detailing for earthquake resistance, with bars ribbed or smooth, continuous or lap-spliced in the plastic hinge. Most of the models, or earlier versions based on a smaller data-bank, were adopted in Eurocode 8-Part 3 and/or fib MC2010, for performance- and displacement-based seismic design, assessment or retrofitting. So, the paper serves as a background document for the models adopted in these codes, improving and extending them, or presenting new ones.

}, author = {Fardis, MN and Biskinis, D and Grammatikou, S} } @conference {684, title = {Strength, deformation capacity and failure mode of RC walls in cyclic loading}, booktitle = {4th International fib Congress and Exhibition}, year = {2014}, address = {Mumbai, India}, abstract = {A database of 621 cyclic tests of RC walls is utilized to evaluate past models for the cyclic strength and deformation capacity of the wall and to develop/calibrate new ones. From the observed damage the failure mode is classified as in flexure, diagona l tension or compression before or after flexural yielding, or in sliding shear. Past models being evaluated on the basis of the tests include models proposed by two of the authors and adopted in Eurocode 8-Part 3 and/or MC2010 for (a) flexural strength, (b) the cyclic shear strength after flexural yielding (as affected by the imposed ductility demand) and (c) the cyclic chord rotation capacity in flexure. Walls with height-to-length ratio less than 1.2 are considered separately, as their shear failure requires different models: past models are commented and a new one proposed and calibrated on the basis of 130 cyclic tests of squat walls. Past models for sliding shear strength are evaluated and modified on the basis of 29 cyclic tests with that failure mode: a new model is proposed for the possibility of uncontrolled sliding during a load reversal at a point in time when the flexural crack at the base is open throughout the section and only dowel action of the still elastic vertical bars is available to resist the shear force. There is good agreement of the predicted cyclic strength and/or deformation capacity per failure mode; the prediction of the most likely mode in the tests of the database is also satisfactory.}, author = {Grammatikou, S and Biskinis, D and Fardis, MichaelN} }