Response Of Masonry Structures Research Articles

Modelling rocking response via equivalent viscous damping

SummaryThe assessment of the out‐of‐plane response of masonry structures has been largely investigated in literature assuming that walls respond as rigid or semi‐rigid bodies, and relevant equations of motion of single‐degree‐of‐freedom and multi‐degree of freedom systems have been proposed. Therein, energy dissipation has been usually modelled resorting to the classical hypotheses of impulsive dynamics, delivering a velocity‐reduction coefficient of restitution applied at impact. In fewer works, a velocity‐proportional damping force has been introduced, by means of a viscous coefficient being constant or variable. A review of such models is presented, a criterion for equivalence of dissipated energy is proposed, equations predicting equivalent viscous damping ratios are derived and compared with experimental responses. Finally, predictive equations are examined in terms of incremental dynamic analyses for large sets of natural ground motions.

Modelling one-way out-of-plane response of single-leaf and cavity walls

Existing unreinforced masonry (URM) buildings have often exhibited both damage and collapse in the out-of-plane (OOP) direction due to the activation of a local mechanism when subjected to earthquake excitations. The assessment of the out-of-plane response of masonry structures has been largely studied in the literature, typically assuming walls responding as rigid blocks or assemblies of rigid bodies. This paper presents a single-degree-of-freedom (SDOF) numerical model for the analysis of the dynamic OOP behaviour of URM walls or portion of walls. It takes into account both the linear and the non-linear rocking response phase of URM walls. The numerical model has been developed to capture the experimental dynamic response of both single leaf and cavity wall specimens subjected to a pure one-way bending action with both top and bottom end supports of the wall moving simultaneously. A detailed investigation into the force–displacement relationships characterising both wall typologies has been carried out in order to provide reliable parameters for the simulation of their dynamic behaviour. Particular emphasis is placed on the energy dissipation involved in such mechanisms. Different equivalent viscous damping models have been adopted and compared in order to identify the most appropriate one to capture the dependency of the damping phenomenon on the oscillation amplitude and subsequently the system frequency.

Review of Blast Loading Models, Masonry Response, and Mitigation

Different models for prediction of blast loading, response of masonry structure against blast load, and various mitigation strategies are discussed. Variation of peak positive incident pressure with scale distance in free field spherical burst and surface burst scenarios, proposed by different researchers, is presented and compared. The variation is found significant in the region of small scaled distances. Blast wave parameters in urban environment have been found different from the free field scenario. Effects of geometry, boundary conditions, and material properties on response of masonry buildings were found significant. Different mitigation strategies such as blast wall, landscaping, architecture, and retrofitting techniques are presented.

Fluid–solid interaction dynamic response of masonry structures under debris flow action

Debris flow is becoming increasingly frequent and serious with the destruction of environment, which causes extensive damage to the environment and huge losses to people’s livelihoods, and even threatens people’s safety. In order to obtain the fluid–solid coupling dynamic characteristics for the masonry structures under the influence of the debris, the ANSYS finite element analysis software is used in this paper. By investigating different debris flows or different fluid fields on the same masonry structure, and the same debris flow with different high or wide masonry structures, the results show: the flow rate and width of debris flow have an important impact on stress in masonry structure and larger stress will occur in masonry structures when the debris flows have a narrower width and higher flow rate. In addition, different types of masonry structures will resist the impact of debris flows differently, resulting in different stress levels even under the same debris flow. Typically, masonry structures with higher height and larger length/width ratio will produce higher stress.

Pseudo-Dynamic Test of Brick Masonry under Different Earthquake Motion

For further study on the influence of ground motion on the seismic performance of brick masonry structure, two masonry buildings were designed and constructed according to common structure style in towns and villages. Two full-scale buildings were subjected to different earthquake motion using pseudo-dynamic test. The earthquake motions are artificial earthquake motion and strong motion recording. This paper presents hysteretic behavior and deformation under horizontal seismic action. Crack propagation of masonry structure is analyzed. These tests verify that displacement response of masonry structures under different ground motion is pretty much the same. Tie-column and ring-beam can effectively confined brick wall. The cracks are mostly diagonal cracks caused by shear failure.

Nonlinear response of masonry wall structures subjected to cyclic and dynamic loading

The assessment of the dynamic or seismic performance of complex structures often requires the integration in the time domain of the structural equation of motion in the frame of a nonlinear analysis. Although sophisticated methods have been developed for the nonlinear analysis of masonry wall structures, including the macro- and micro-modeling approaches, these require large computational effort still limiting the extent and complexity of the structures analyzed. This paper presents an alternative method based on the Generalized Matrix Formulation for masonry skeletal structures and load bearing wall systems, which has been proved as an efficient formulation for the analysis of the strength capacity of these kinds of structures (Roca et al. (2005) [17]). The basic formulation has been complemented with a uniaxial cyclic constitutive model for masonry and a time integration scheme. The ability of the resulting approach to predict the nonlinear dynamic response of masonry structures is shown through its application to the time domain analysis of an experimental scale masonry building with available experimental results on its dynamic response.