Equivalent Strut Width for Partial Infilled Frames

The partially infilled frames are considered vulnerable in terms of captive column effect for the events of earthquakes. Many reinforced concrete buildings have been affected due to captive column effects. Experimental study has been done to verify the captive column effect and its failure modes for partially infilled frames and the results have been compared with the ones obtained for a bare frame subjected to lateral loading. The results of experimental study have also been compared with some analytical results and the verification of equivalent strut width proposed by one of the authors has been done. From the experimental point of view, it is understandable that due to lateral loading to partially infilled frames, the damage pattern is diagonal and the failure of column occurs at the column-wall joint at the upper side of the wall. It is also seen that for fifty percent partially infilled frames, the stiffness of bare frame is enhanced slightly, however, the failure in the column during lateral loading indicates that the columns are subjected to high shear due to the presence of partial infill.

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EQUIVALENT STRUT WIDTH FOR MODELING R.C. INFILLED FRAMES

JES. Journal of Engineering Sciences ◽

10.21608/jesaun.2013.114763 ◽

2013 ◽

Vol 41 (3) ◽

pp. 851-866 ◽

Cited By ~ 1

Author(s):

K. H. Abdelkareem ◽

F. K. Abdel Sayed ◽

M. H. Ahmed ◽

N. AL-Mekhlafy

Keyword(s):

Infilled Frames ◽

Equivalent Strut

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Proposed macro-model for the analysis of infilled frame structures

Bulletin of the New Zealand Society for Earthquake Engineering ◽

10.5459/bnzsee.40.2.69-77 ◽

2007 ◽

Vol 40 (2) ◽

pp. 69-77 ◽

Cited By ~ 62

Author(s):

Francisco J. Crisafulli ◽

Athol J. Carr

Keyword(s):

Simple Procedure ◽

Computer Software ◽

Shear Behaviour ◽

Concrete Frames ◽

Infilled Frames ◽

Macro Model ◽

Masonry Infills ◽

Equivalent Strut ◽

Modes Of Failure ◽

Shear Spring

Reinforced concrete frames infilled with masonry panels constitute an important part of the high-risk structures in different regions of high seismicity. In some developing countries, they are still used as main structural system for low to medium rise buildings. Consequently, reliable methods to analyse infilled frames are required in order to reduce the loss of life and property associated with a possible structural failure. The equivalent strut model, proposed in the 1960s, is a simple procedure to represent the effect of the masonry panel. Several improvements of the original model have been proposed, as a result of a better understanding of the behaviour of these structures and the development of computer software. This paper presents a new macro-model for the evaluation of the global response of the structure, which is based on a multi-strut formulation,. The model, implemented as 4-node panel element, accounts separately for the compressive and shear behaviour of masonry using a double truss mechanism and a shear spring in each direction. The principal premises in the development of the model are the rational consideration of the particular characteristics of masonry and the adequate representation of the hysteretic response. Furthermore, the model is able to represent different modes of failure in shear observed for masonry infills. The comparison of analytical results with experimental data showed that the proposed model, with a proper calibration, is able to represent adequately the in-plane response of infilled frames.

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Numerical modelling of out-of-plane response of infilled frames: State of the art and future challenges for the equivalent strut macromodels

Engineering Structures ◽

10.1016/j.engstruct.2016.10.012 ◽

2017 ◽

Vol 132 ◽

pp. 110-122 ◽

Cited By ~ 50

Author(s):

P.G. Asteris ◽

L. Cavaleri ◽

F. Di Trapani ◽

A.K. Tsaris

Keyword(s):

Numerical Modelling ◽

State Of The Art ◽

Infilled Frames ◽

Equivalent Strut ◽

Out Of Plane ◽

Future Challenges

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Masonry infilled steel frames subjected to dynamic load

Canadian Journal of Civil Engineering ◽

10.1139/l89-130 ◽

1989 ◽

Vol 16 (6) ◽

pp. 877-885 ◽

Cited By ~ 11

Author(s):

J. L. Dawe ◽

A. B. Schriver ◽

C. Sofocleous

Keyword(s):

Steel Frames ◽

Dynamic Strength ◽

Dynamic Responses ◽

Analytical Models ◽

Braced Frame ◽

Infilled Frames ◽

Masonry Infill ◽

Equivalent Strut ◽

Scale Models ◽

Joint Rigidity

Experimentally determined dynamic responses of ten scale models of masonry infilled steel frames were compared with the results of three simple analytical models. Effects investigated included stiffening and strengthening contribution of the masonry infill, degradation of the system, motion intensity, frame stiffness, and rotational joint rigidity at slab-to-column intersections. Tests on one-third scale models, subjected to sinusoidal motions, revealed that masonry infill markedly increases the dynamic strength and stiffness of the system. At weak-to-moderate motions (below 0.5 g), models exhibited a nonlinear response before the final failure, while strong motions accelerated the system degradation rate. Stiffer frames and rotationally rigid joints resulted in significantly increased system dynamic strength. A braced frame model wherein cross-bracing replaces the panel action adequately predicted linear and lower-region nonlinear responses of infilled frames with flexible column-to-slab rotational conditions. Satisfactory predictions of the linear response of framed walls with rigid column-to-slab rotational conditions were made with a single degree of freedom model. The third analytical model based on an equivalent strut technique was found to be unsatisfactory for predicting dynamic response of masonry infilled frames. Key words: masonry panel, steel frame, shear, dynamic, analytical, experimental.

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A new dynamic identification technique: application to the evaluation of the equivalent strut for infilled frames

Engineering Structures ◽

10.1016/s0141-0296(03)00023-3 ◽

2003 ◽

Vol 25 (7) ◽

pp. 889-901 ◽

Cited By ~ 26

Author(s):

L. Cavaleri ◽

M. Papia

Keyword(s):

Dynamic Identification ◽

Infilled Frames ◽

Equivalent Strut ◽

Identification Technique

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SEISMIC DESIGN OF MASONRY-INFILLED FRAMES: A REVIEW OF CODIFIED APPROACHES

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.2020.7(2).str-48 ◽

2020 ◽

Vol 7 (2) ◽

Author(s):

Sonam Dorji ◽

Hossein Derakhshan ◽

Tatheer Zahra ◽

David P. Thambiratnam ◽

Alireza Mohyeddin

Keyword(s):

Seismic Design ◽

Paradigm Shift ◽

Generic Model ◽

Infilled Frames ◽

Analysis And Design ◽

High Stiffness ◽

Equivalent Strut ◽

Influencing Parameters ◽

Modeling Strategy ◽

Masonry Infilled Frames

This paper reviews the approach of eleven national codes on the analysis and design of masonry-infilled frames. It is shown that, in general, codes can be divided into two groups. The first group isolates the masonry and frame members by providing gaps to minimize the interaction between them. This method ensures that the complexities involved in analyzing the structure is avoided. However, the width of the gaps recommended is different for each of the codes. The second group takes advantage of the presence of high stiffness and strength masonry infill. In this technique, an equivalent-strut modeling strategy is mostly recommended. It is shown that the strut model suggested in each of the codes is different. An attempt to obtain a generic model for masonry-infilled frame failed largely due to the existence of many behavior-influencing parameters. Finally, it is suggested to have a paradigm shift in the modeling strategy where the masonry-infilled frames are classified into different categories and a model is suggested for each of them.

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Investigation of Diagonal Strut Actions in Masonry-Infilled Reinforced Concrete Frames

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-020-00440-x ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Seung-Jae Lee ◽

Tae-Sung Eom ◽

Eunjong Yu

Keyword(s):

Reinforced Concrete ◽

Failure Mode ◽

Yield Criterion ◽

Friction Angle ◽

Concrete Frames ◽

Element Analysis ◽

Reinforced Concrete Frames ◽

Infilled Frames ◽

Masonry Infills ◽

Push Down

AbstractThis study analytically investigated the behavior of reinforced concrete frames with masonry infills. For the analysis, VecTor2, a nonlinear finite element analysis program that implements the Modified Compression Field Theory and Disturbed Stress Field Model, was used. To account for the slip behavior at the mortar joints in the masonry element, the hyperbolic Mohr–Coulomb yield criterion, defined as a function of cohesion and friction angle, was used. The analysis results showed that the lateral resistance and failure mode of the infilled frames were significantly affected by the thickness of the masonry infill, cohesion on the mortar joint–brick interface, and poor mortar filling (or gap) on the masonry boundary under the beam. Diagonal strut actions developed along two or three load paths on the mortar infill, including the backstay actions near the tension column and push-down actions near the compression columns. Such backstay and push-down actions increased the axial and shear forces of columns, and ultimately affect the strength, ductility, and failure mode of the infilled frames.

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