Analysis Of Masonry-infilled Frames Research Articles

A multi-strut model for the hysteresis behavior and strength assessment of masonry-infilled steel frames with openings under in-plane lateral loading

The analysis of masonry-infilled frames (MIFs) with openings is a complex problem in structural engineering. Previous studies have shown that when an infill panel has an opening, it behaves as four separate subpanels around the opening. Therefore, it can be conceived that a perforated masonry infill panel behaves as four inclined compression-only equivalent struts in each direction. This paper presents a multi-strut model (MSM) using the equivalent strut concept for the nonlinear analysis of masonry-infilled steel frames (MISFs) with openings. The MSM consists of two inelastic side pier struts connected to the surrounding frame joints using rigid trusses representing the subpanels above and below the opening. The model incorporates an envelope curve and a hysteretic law to define the initial stiffness, peak strength, and post-peak strength behavior of the inclined struts under reversal loads. The MSM was used to analyze the lateral load behavior of tested MISFs with openings found in the literature. It was shown that the proposed model is efficient and can predict the stiffness and capacity of MISFs with openings under both monotonic and cyclic lateral loadings.

Sensitivity and Reliability Analysis of Masonry Infilled Frames

Sensitivity and Reliability Analysis of Masonry Infilled Frames

Experimental analysis of masonry infilled frames using digital image correlation

A measurement technique (digital image correlation) is used for a critical evaluation of simplified models for infilled framed structures. It allows for the assessment of displacement and strain fields in the panel of interest. Several specimens, including infilled and partially infilled frames were subjected to cyclic lateral loads. It was found that two very different deformation mechanisms appear in the masonry panels namely, a first one during the hardening phase and another one, completely different, during the softening stage. For the former, strain concentration bands are observed. After the peak load, horizontal bands appear in the middle of the panels. The Polyakov assumption, i.e. that the panel can be replaced by struts in the analysis, is validated in the hardening stage. However, the orientation of the struts suggested in the literature was not found experimentally. The experimental results demonstrate that the inclination of the bands depends on the brick dimensions and arrangement. Further, the final failure mechanism corresponds to a sliding shear mode.

Realistic FE Models to Enable Push-Over Non Linear Analysis of Masonry Infilled Frames

The assessment of low engineered masonry infilled reinforced concrete frame (LE-MIRCF) buildings is ex- plored using a finite element based modelling technique that enables the representation of the masonry infills in a non- linear finite element analytical environment. A mezo-modelling approach has been developed and implemented for the masonry infills, while fibre elements are used to represent the reinforced concrete members and a spring element for the interface between these and the masonry. The methodology developed also specifically enables for the identification of the onset of shear failure in the columns. To date the approach has been used to explore the effects of having different patterns of masonry infill distributions and openings, throughout internal frames of a five storey LE-MIRCF structure. The resulting structures were analysed in the inelastic range, and their performance assessed. The results show that the provision of masonry infills is not always dam- aging but nor is always advantageous. Rather it very much depends on the particular infill configuration. Scope: The development and implementation of a simple yet sufficiently accurate modelling technique that enables the representation of the masonry infills, in an analytical environment suitable for use in the assessment of structures under seismic excitation.

Behaviour and analysis of masonry‐infilled frames

AbstractMasonry infills are frequently used as interior partitions and exterior walls in buildings. They are usually treated as non‐structural elements, and their interaction with the bounding frame is often ignored in design. The performance of such structures during an earthquake has attracted major attention. Even though frame–infill interaction has sometimes led to undesired structural performance, recent studies have shown that a properly designed infilled frame can be superior to a bare frame in terms of stiffness, strength, and energy dissipation. A number of different analytical models have been developed to evaluate infilled structures. Nevertheless, most of the models proposed today have been validated with limited experimental data, and they have often yielded different performances when compared with recent test data. Limit analysis methods that can account for a variety of possible failure modes seem to be the most promising approach. However, these methods need to be further refined and validated in a systematic manner before they could be used in engineering practice. Sophisticated finite element models have also been developed to analyse infilled structures. While these models are general and widely applicable to different types of infilled frames, they should be used with caution because they could be easily misused and lead to unconservative results. This paper summarizes some of the recent findings and developments on the behaviour and modelling of infilled structures, and provides thoughts for future research.

A computer model for predicting infilled frame behaviour

A computer model is developed for the structural analysis of masonry infilled frames. Structural interaction of the panel and its peripheral frame is considered. Various failure criteria are incorporated into the model and special elements are developed to account for masonry failure by cracking and crushing as well as to account for the complex interaction of frame and panel. Comparison of analytical findings with the results of 31 laboratory tests on steel and reinforced concrete infilled frames showed favourable correlation and verification of the computer model.Key words: masonry, infill, frame, steel, concrete, computer, model, testing, correlation, failure.

Modeling of Masonry Infill Panels for Structural Analysis

An analytical macromodel based on an equivalent strut approach integrated with a smooth hysteretic model is proposed for representing masonry infill panels in nonlinear analysis of frame structures. The hysteresis model uses degrading control parameters for stiffness and strength degradation and slip “pinching” that can be implemented to replicate a wide range of hysteretic force-displacement behavior resulting from different design and geometry. The paper presents the development of the hysteretic model and the definitions of the control parameters, which can be determined using any suitable theoretical model for masonry infills. An available theoretical model for simplified engineering evaluation of masonry infilled frames was explored for estimating the control parameters of the proposed macromodel. The macromodel was incorporated in a nonlinear structural analysis program, IDARC2D Version 4.0, for quasi-static cyclic and dynamic analysis of masonry infilled frames. Simulations of experimental force-deformation behavior of prototype infill frame subassemblies are performed to validate the proposed model. A lightly reinforced concrete frame structure is analyzed for strong ground motions to evaluate the influence of masonry infill panels on the dynamic response.

Seismic design and analysis of masonry-infilled frames : V. K. R. Kodur, M. A. Erki & J. H. P. Quenneville, Canadian Journal of Civil Engineering, 22(3), 1995, pp 576–587

Seismic design and analysis of masonry-infilled frames : V. K. R. Kodur, M. A. Erki & J. H. P. Quenneville, Canadian Journal of Civil Engineering, 22(3), 1995, pp 576–587

Seismic design and analysis of masonry-infilled frames

A simple analytical procedure, which can be used by practicing engineers, for the seismic design of masonry-infilled frames is presented. The analysis procedure, based on the experimental and analytical studies reported in the literature, accounts for the effect of infills in all three stages, namely, in computing seismic loading, in predicting response of the infilled frame, and in determining the strength of the infilled frame. Seismic loading is computed using the dynamic properties of the structure rather than arbitrary empirical relationships as recommended in design codes. Recommendations regarding the choice of infilled frame idealization, structural damping ratio, earthquake design spectrum, structural irregularity, and computational aids are made. Practical guidelines, which can be implemented during the construction phase and which have beneficial effects on the behaviour of infilled frames, are provided. Application of the proposed analytical procedure in a design situation is demonstrated through a numerical example, and it is shown that infills can be accounted for in the seismic design of frames during the normal course of design. Key words: masonry, infilled panels, frame behaviour, seismic design.