128,266 research outputs found
Totem Totem/ Floppy
No full textFloppy was produced as an outcome of the GCAS and Art Incubator residency program in Singapore. The exhibition at Substation gallery was financial supported by the Australian High Commission and was also funded with an Arts Victoria Export and Touring grant. The second instance was exhibited at Milani Gallery, Brisbane
Advanced finite element modeling of textile-reinforced mortar strengthened masonry
No full textFabric-reinforced cementitious matrix (FRCM) strengthening is an innovative technology for effective reduction of seismic vulnerability of existing masonry and historical structures. At present, numerical modeling strategies for evaluation of the in- and out-of-plane performance of masonry structures strengthened with these composites are in their embryonic stage. The present chapter is aimed at presenting two alternative approaches to such strategies. In particular, a detailed 3D heterogeneous and an inexpensive homogenization approach are reviewed. In the first model, brick and mortar joints are meshed separately with 3D eight-noded elements, whereas FRCM is discretized using trusses (fiber grid) and 3D eight-noded elements (cementitious matrix). These 3D elements are made in all cases with a softening and damage behavior with plasticization, both in tension and compression, using the concrete damage plasticity model. In the homogenization approach, masonry is substituted with an equivalent nonlinear orthotropic material exhibiting softening. The elementary cell is discretized using a few triangular elastic elements (bricks) and holonomic interfaces (joints) in which all the nonlinearities are lumped. The FRCM reinforcement is applied to the homogenized masonry using equivalent trusses with limited tensile strength and fragile behavior, connecting adjoining rigid elements. Equivalent mechanical properties of the trusses can be eventually tuned accounting for FRCM debonding or rupture of the fibers. The pros and cons of the two numerical procedures are discussed with respect to their reliability in fitting experimental force-displacement curves and crack patterns, as well as to the rather different computational effort required by the two strategies
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Seismic assessment of historical masonry structures through advanced nonlinear dynamic simulations: applications to castles, churches, and palaces
No full textThe preservation of architectural heritage against earthquakes is currently a topic of increasing interest in Italy and requires an accurate seismic response assessment of the structures. Recent Italian seismic events have shown that severe damage or partial collapse can be caused to historical buildings even by low-to-moderate intensity earthquakes. Structural analysis is a fundamental tool to better evaluate the seismic response and vulnerability of historical buildings and define effective strengthening interventions: in particular, the use of advanced numerical tools to perform three-dimensional (3D) nonlinear dynamic analyses allows obtaining a thorough detailed knowledge of the seismic behavior of such a typology of structures. This chapter investigates the seismic response and damage distribution of three important historical masonry constructions of the outstanding cultural heritage in Mantua (Northern Italy) after the 2012 Emilia earthquake: the recent seismic sequence and the consequent significant crack patterns observed in the postearthquake survey phase pointed out their vulnerability to small seismic actions. Detailed and representative 3D finite element models of the historical masonry constructions are developed and nonlinear dynamic analyses are carried out to gain a deep numerical insight into the seismic response of the three structures, identifying the damage patterns and the most vulnerable parts for different seismic intensity levels
Homogenized non-linear dynamic model for masonry walls in two-way bending
No full textA simple homogenization approach accounting for mortar joint damaging is presented, suitable to analyse entire panels in two-way bending in the non-linear dynamic field. A rectangular running bond elementary cell (RVE) is subdivided into several layers along the thickness and, for each layer, a discretization where bricks are meshed with plane-stress three-noded triangular elements and joints are reduced to interfaces with damaging behaviour is assumed. Non linearity is due exclusively to joints cracking, which exhibit also a frictional behaviour with limited tensile and compressive strength with softening. A damaging material is utilized for joints in order to properly take into account the actual opening and closure of cracked mortar under cyclic loads. Finally, macroscopic curvature bending moment diagrams are obtained integrating along the thickness in-plane micro-stresses of each layer.
Homogenized masonry flexural response under load-unload conditions is then implemented at a structural level in a FE non-linear code based on a discretization with rigid three-noded elements and elasto-damaging interfaces where elastic and inelastic deformation is allowed only for flexural actions. The two step model proposed is validated both at a cell and structural level, comparing results obtained with both experimental data and existing macroscopic numerical approaches available in the literature
1967-1968 -- Miscellaneous, Assorted Letters and Photographs -- letter, 1967-07-28
No full textLetter from Milani, Piero A. to Sabin, Albert B. dated 1967-07-28.Sabin Collection Fair Use Policy</a
Has Globalization Transformed U.S. Macroeconomic Dynamics?
No full textThis paper estimates a structural New Keynesian model to test whether globalization has changed the behavior of U.S. macroeconomic variables. Several key coefficients in the model - such as the slopes of the Phillips and IS curves, the sensitivities of domestic inflation and output to "global" output, and so forth - are allowed in the estimation to depend on the extent of globalization (modeled as the changing degree of openness to trade of the economy), and, therefore, they become time-varying. The empirical results indicate that globalization can explain only a small part of the reduction in the slope of the Phillips curve. The sensitivity of U.S. inflation to global measures of output may have increased over the sample, but it remains very small. The changes in the IS curve caused by globalization are similarly modest. Globalization does not seem to have led to an attenuation in the effects of monetary policy shocks. The nested closed economy specification still appears to provide a substantially better fit of U.S. data than various open economy specifications with time-varying degrees of openness. Some time variation in the model coefficients over the post-war sample exists, particularly in the volatilities of the shocks, but it is unlikely to be related to globalization.Globalization and Inflation; Global slack; Openness; New Keynesian model; Expectations and adaptive learning; DSGE model with time-varying coefficients
A fast modeling approach for numerical analysis of unreinforced and FRCM reinforced masonry walls under out-of-plane loading
No full textA new discretized homogenization approach is proposed in this study in order to predict the behavior of unreinforced and FRCM reinforced masonry structures. The proposed approach allows overcoming the common disadvantages of the existing homogenization approaches: (a) being difficult to implement and (b) not allowing to couple the in-plane and out-of-plane actions. Reference experimental results and detailed numerical modeling are used for validation of the proposed modeling strategy. In the proposed model, the elastic cells are linked by homogenized interfaces. The mechanical properties coming from the homogenization procedures are lumped at the interfaces by means of the generic Concrete Damage Plasticity model, allowing easy implementation and avoiding computational issues peculiar to other approaches available in the literature. The new approach shows accurate results in predicting the global behavior and the damage pattern for both unreinforced and FRCM strengthened masonry walls. The results are promising also with a view to be applied for more complex reinforced applications as double curvature masonry structures
Homogenization limit analysis
No full textFour approaches for the determination of the homogenized strength domain of running or header bond masonry walls, either in-plane or transversely loaded, are proposed and compared. The first one yields a lower bound, where the elementary cell is subdivided into a few rectangular subdomains and the microstress field is expanded using polynomial expressions. The second one is also based on the safe theorem of limit analysis, but joints are reduced to interfaces and bricks are subdivided into a few constant stress triangular elements. The third one is a “compatible identification” procedure, which belongs to the upper bound family, where joints are reduced to interfaces and bricks are assumed to be infinitely resistant. The last approach is also a kinematic (upper bound) procedure based on the so called Method of Cells, where the elementary cell is subdivided into six rectangular subcells with preassigned polynomial velocity fields fulfilling suitable periodic conditions. The first and last models have the advantage of taking the finite thickness of the joints into account. Although in the second approach joints are reduced to interfaces with frictional behavior, failure inside units (bricks or blocks) can be captured as well. In the framework of the upper bound theorem of limit analysis, simple linear programming optimization problems are derived to estimate the homogenized strength domains of masonry. The main advantages of the proposed approaches are the following: (1) the homogenized failure surface can be directly estimated, without the need for performing expensive step-by-step elasto-plastic finite element nonlinear analyses; (2) as the linear programming problem involves very few variables in all approaches, it is intrinsically very robust and allows, at the same time, the failure surface to be easily estimated. An insight into pros and cons of the utilization of the different approaches is provided, with reference to realistic examples
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