List of publications
Publication: Finite element modeling and shake-table testing of unidirectional infill masonry walls under out-of-plane dynamic loads (2011)
Preparation and upload by:
Filip Anic, Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek
Publication abstract (click to enlarge):
Publication abstract (click to shrink):
The paper presents the results of an experimental campaign on the behaviour of engineered masonry infillwalls subjected to both in- and out-of-plane loading. The dynamic out-of-plane response of unreinforced masonry walls is investigated. The study combines analytical, numerical, and experimental methodologies. The paper focuses on structural schemes that involve supporting at the base and the
The paper presents the results of an experimental campaign on the behaviour of engineered masonry infillwalls subjected to both in- and out-of-plane loading. The dynamic out-of-plane response of unreinforced masonry walls is investigated. The study combines analytical, numerical, and experimental methodologies. The paper focuses on structural schemes that involve supporting at the base and the top and yield a unidirectional (one-way) flexural action. First, the modeling concepts for the nonlinear dynamic analysis are discussed and used as a basis for a finite element formulation. The element is based on a first-order shear deformation theory with large displacements, moderate rotations, small strains, material nonlinearity, and a Rayleigh type of viscoelastic damping. The nonlinearities due to cracking and the inelastic response under cyclic compression are introduced through the constitutive model for the mortar. The experimental part includes shake-table testing under different levels of out-of-plane excitation and compressive loading. The experimental results and the numerical model quantify a range of physical phenomena, including the dynamic arching and rocking effects, the coupling of the axial (in the height direction) and the out-of-plane responses, the role of axial loading, and the vulnerability of the masonry construction to dynamic loads. The comparison between the numerical results and the experimental results examines the capabilities of the model and gains insight into the nonlinear dynamics of the masonry wall.
In modern structures, it is mostly found in the form of external or internal infill walls. Such walls are usually not considered as major load carrying members. Yet, extensive seismic excitation, seismic inter-story drift, wind loads, or sudden loading of the peripheral structural system may yield significant dynamic out-of-plane loading of the masonry wall. These loads may end up with severe damage to the wall itself or even with collapse and potential injury of occupants. In that sense, the dynamic response becomes a factor affecting the safety of the structure and dictating the need for a dynamic structural upgrade.
AIM AND SCOPE
The objective of the paper is to gain insight into the dynamic behavior of the wall and to address the modeling and analysis of this behavior. The paper combines analytical and numerical methodologies with shake-table experiments. Both the modeling and the experiments are more oriented toward modern infill walls but the modeling concepts and the some of the experimental observations are also relevant to load bearing walls under unidirectional loading and supporting conditions. The analytical phase adopts some of the modeling concepts of Hamed and Rabinovitch and derives an FE based computational and modeling tool.
DESIGN AND CONSTRUCTION OF THE TEST SPECIMENS:
The experimental part has focused on shake-table testing of masonry walls subjected to out-of-plane dynamic loads. A full-scale masonry wall made of hollow concrete units and a cementitious mortar has been tested under different levels of dynamic excitation. The wall has been supported at its top and bottom simulating the interaction with the upper slab and the evolution of a unidirectional type of out-of-plane dynamic response. In order to simulate a limited level of vertical load transferred by the upper slab, the wall has been tested under different levels of axial compressive loading.
The modeling assumptions follow Hamed and Rabinovitch and assume that the boundary conditions, the construction method, the width to height ratio, and the loading pattern yield a unidirectional (beam-like) flexural action through the height of the wall. It is also assumed that the vertical loads acting on the wall due to interaction with adjacent components are uniform through the width. Particularly in case of infills, the determination of such a vertical load can be very difficult. In addition, since the vertical load is usually transferred by a horizontal beam, it could vary along the width of the wall. The model derived here does not consider these effects. Based on the above assumptions, the model adopts a beam theory, assumes that the stresses are uniform through the width, and accounts for flexural and axial actions in one direction only. In addition, the model assumes that the pattern of the masonry construction of the wall repeats itself in the width direction and therefore defines a ‘‘periodic’’ or ‘‘repeating’’ pattern. Under these conditions, and by neglecting the effect of the head joints, the wall can be divided into vertical strips that are similar one to another in terms of construction patterns and structural behavior. All of these strips are represented by a single ‘‘characteristic strip’’ that periodically repeats itself through the width. The width of each strip (and thus the width of the characteristic strip) may vary from half the width of a single masonry unit to the width of the entire wall.
The experimental and numerical results have revealed some of the unique structural aspects of the dynamic response of the masonry wall. Among these the cracking at the bed joints and lack of cracking at the masonry units, the development of dynamic arching and rocking effects, the temporal variation of the axial force, the coupling between the axial and the out-of-plane responses, and the effect of compressive loading have been observed. The results have demonstrated and quantified how changes to the structural state of the wall such as the reduction of level of compression, changes to the boundary conditions, or deterioration of the level of the rotational constraint (in cases such boundary condition applies to the realistic configuration of the wall) can critically increase its vulnerability to the dynamic load.
The comparison of the numerical results with the experimental ones has indicated that many of the physical effects observed in the experiment have also been captured and quantified by the analysis, generally with a reasonable agreement. In some cases, the comparison has revealed some discrepancies that may stem from aspects that have not been taken into account or from parameters that have only been estimated. Yet, the general trend of agreement between the numerical and the experimental results has pointed in favor of the potential ability of the FE modeling to capture the important aspects of the nonlinear dynamic response of the wall. In that sense, it provides a relatively simple and accessible computational tool for the dynamic analysis. This tool can also be coupled with other analyses, implemented in a broader structural analysis platform, and extended to cases that are more complicated such as bidirectional behavior and external retrofit.
RECOMMENDATIONS FOR FUTURE RESEARCH
None were specified.
Please choose test setup.
Please choose experiment.
ERASMUS+ Key Action 2 – Strategic Partnerships
“Forecast Engineering: From Past Design to Future Decisions”
The creation of these resources has been funded by the ERASMUS+ grant program of the European Union under grant no. 2016-1-DE01-KA203-002905. Neither the European Commission nor the project‘s national funding agency DAAD are responsible for the content or liable for any losses or damage resulting of the use of these resources.