Dome of the Basilica of Santa Maria Degli Angeli in Assisi: Static and Dynamic Assessment

This study presents the results of the static and dynamic assessment of the dome of the Basilica of Santa Maria degli Angeli in Assisi, designed by Galeazzo Alessi. The first section is devoted to an overview of the masonry domes designed by the Italian architect and focuses on the structural solutions adopted in the several cases described to better understand Alessi’s designing skills. In the second part, the drum-dome system is analyzed in order to attain a structural assessment. The static assessment is performed by means of limit analysis and finite element model approaches with non-linear mechanical behavior. The obtained results are consistent with the detected crack pattern and confirm the suitability of the reinforcement steel rings applied to the drum. The seismic assessment has been performed by response spectrum analysis. Due to the lack of specific information, a probabilistic approach for the material mechanical properties was used. The results obtained highlight an adequate seismic response of the structure that can be attributed to the dynamic properties of the slender drum-dome system. This finding justifies the good performance of the structure during the seismic events of 1832 and 1997.     

Seismic History of the Church of San Pietro Di Coppito in L’Aquila

After the terrible 18th-century earthquakes—in L’Aquila in 1703, Lisbon in 1755, and Reggio Calabria in 1783—specific anti-seismic precepts were introduced in the rules of the art of masonry construction. Scrupulously adhered to in the first years after the earthquake, those precepts gradually ceased to be used until they were almost completely forgotten, centuries later, by which time the earthquake had become a distant memory. The church of San Pietro di Coppito, one of the most important churches of L’Aquila, is emblematic of this singular process. Deeply transformed in accordance with new anti-seismic construction techniques after it was particularly badly damaged in the terrible 1703 earthquake, the church was subjected, in the 1970s, to drastic alterations by the Commissioner Mario Moretti, who demolished all the baroque additions and redesigned it in the “medieval Abruzzo” style, eliminating in the process the intelligent anti-seismic provisions introduced in the 18th century. In addition to documentary purposes, this work aims to underline the effectiveness of this early 18th-century example of anti-seismic engineering in the belief that the constructive solutions it employed could still form a valid architectural and structural model in view of the massive restoration task for which, unfortunately, L’Aquila is still waiting today.     

Force-Based Beam Finite Element (FE) for the Pushover Analysis of Masonry Buildings

A simplified approach for analyzing the nonlinear response of masonry buildings, based on the equivalent frame modeling procedure and on the nonlinear equivalent static analyses, is presented. A nonlinear beam finite element (FE) is formulated in the framework of a force-based approach, where the stress fields are expanded along the beam local axis, and introduced in a global displacement-based FE code. In order to model the nonlinear constitutive response of the masonry material, the lumped hinge approach is adopted and both flexural and shear plastic hinges are located at the two end nodes of the beam. A classical elastic-plastic constitutive relationship describes the nonlinear response of the hinges, the evolution of the plastic variables being governed by the Kuhn-Tucker and consistency conditions. An efficient element state determination procedure is implemented, which condenses the local deformation residual into the global residual vector, thus avoiding the need to perform the inner loops for computing the element nonlinear response. The comparison with some relevant experimental and real full-scale masonry walls is presented, obtaining a very good agreement with the available results, both in terms of global pushover curves and damage distributions.     

Spatial agency and practising architecture beyond buildings

This paper provides new direction for geographic scholarship on architecture by focusing upon architectural projects that go well beyond designing and producing material objects. Recent work on practising architectures by social and cultural geographers has examined the multiple processes of human and non-human actors that cohere and congeal to produce buildings. Responding to concerns that geographers are failing to work closely with architects, I introduce ideas of spatial agency to examine the practices of architects working beyond buildings. Arguing that the profession has always been under threat, I outline why socially progressive architects are rejecting claims as expert technical problem-solvers or artistic form-givers by instead initiating and contributing towards explicitly spatial projects prioritizing social and economic objectives. By calling for creative engagement with such projects, I set forth an agenda for a politically progressive geography of architecture.     

Methods and Challenges for the Seismic Assessment of Historic Masonry Structures

ABSTRACT

Despite the high vulnerability of historic structures to earthquakes, the approaches for evaluating seismic demand and capacity still appear inadequate and there is little consensus on the most appropriate assessment methods to use. To develop an improved knowledge on the seismic behavior of masonry structures and the reliability of analysis tools, two real-scale specimens were tested on a shake table, and several experts were invited to foresee failure mechanism and seismic capacity within a blind prediction test. Once unveiled, experimental results were simulated using multi-block dynamics, finite elements, or discrete elements. This article gathers the lessons learned and identifies issues requiring further attention. A combination of engineering judgment and numerical models may help to identify the collapse mechanism, which is as essential as it is challenging for the seismic assessment. To this purpose, discrete modeling approaches may lead to more reliable results than continuous ones. Even when the correct mechanism is identified, estimating the seismic capacity remains difficult, due to the complexity and randomness of the seismic response, and to the sensitivity of numerical tools to input variables. Simplified approaches based on rigid body dynamics, despite the considerable experience and engineering judgment required, provide as good results as do advanced simulations.     

Simulation of Shake Table Tests on Out-of-Plane Masonry Buildings. Part (V): Discrete Element Approach

ABSTRACT

The analysis of the shaking table test of a 3-wall stone masonry structure performed with a discrete element model is presented. The numerical model, created with the code 3DEC, employed a rigid block representation and a Mohr-Coulomb joint model. Joint stiffness calibration to match the experimental natural frequencies is discussed, as well as the boundary conditions to simulate the shake table. Comparisons are made with the measured displacements at key locations, and the modes of deformation and fracture of the walls. The DEM model was able to reproduce important features of the shaking table tests. The experimental deformation and near collapse patterns were clearly identifiable in the numerical simulations, which produced displacements within the observed orders of magnitude, for the various levels of excitation.     

南通近代建筑的历史地位和形成特点

南通是中国近代早期的工业基地之一,曾以模范县的美誉闻名于世。南通近代建筑是随着工商业兴起的,它是南通人依靠自己的力量,学习和吸收西方建筑艺术所形成的,在中国近代建筑史上占有一定的地位。南通近代建筑的形成有鲜明的特点,保护好这些建筑,有十分重要的意义。     

Experimental Dynamic Testing and Numerical Modeling of Historical Belfry

The experimental characterization of historical bell towers and wall belfries can provide important information for the calibration of numerical models as well as to implement proper restoration strategies. Within this framework, the presented study is concerned with the experimental dynamic assessment of an ancient belfry dating back to 1537. The structure is part of the “Santa Maria in Aracoeli Church” (Rome, Italy), an important heritage construction placed on the summit of the Capitoline Hill, close to the building that hosts the Major’s office. Several field tests have been conducted using accelerometers, and records obtained under different dynamic loading scenarios have been examined. Moreover, experimental accelerations have been elaborated to estimate the most important modal features of the structure and to validate a finite element model. Field tests have confirmed that severe vibrations are induced when the bells swing, and thus a slight reduction of the swing angle has been suggested in order to provide an immediate and inexpensive benefit to the structure. A new set of field tests demonstrates that the new swing angle is sufficient to reduce the induced vibrations while preserving the original sound.     

Analysis of the Effect of Provisional Ties on the Construction and Current Deformation of Mallorca Cathedral

This article presents the analysis of the structure of Mallorca Cathedral taking into account the influence on the structural behavior of auxiliary iron ties used during the construction process. Recent studies (Roca et al. 2012, 2013) presented some hypotheses about the construction process of the cathedral. This article complements the previous results by considering the use of auxiliary ties as temporary stabilizing device during the construction. Evidence of the use of ties during the construction has been recognized after a comprehensive survey. The study of the role of such ties and the effect of their later removal are studied by a FE analysis carried out on a representative bay of the structure. The study includes a time-dependent FE analysis after the removal of the ties to assess the long-term structural behavior. The results of the numerical analysis are compared with the deformation trends identified by means of a recent monitoring campaign.     

Regeneration and Structural Strengthening of the Fortress of Arnara,Latium, Italy

The fortress of Arnara is a small castle in a high seismic hazard zone in Latium, Italy, which represents a landmark for the local population. It was chosen as a case study, being a perfect example of Middle Age fortress, well preserved during the centuries despite some strong earthquakes damaged it in the past. The project presented here is a significant example of how the interest of a community to regenerate an ancient structure for its re-use can pave the way to a complete structural strengthening, which includes anti-seismic concepts aiming at retrofitting the ancient fortress walls. The overall project joins architectural and structural solutions. The architectural solution aims at a functional reconfiguration of the spaces, so to attract the locals to reuse it, while at the same time highlighting some valuable architectural features of the fortress. The structural solution aims at improving the seismic resistance of the masonry walls with a structural intervention that is respectful and integrates with the existing forms. This was achieved by means of a tenso-structure that has the two-fold role of reconnecting the different portions of the structures and of endowing it with a distinctive architectural sign. This project demonstrates that rediscovery of architectural heritage can also be pursued by proposing a new use for these structures, following an appropriate regeneration strategy that must take into account the cultural features of the territory, being at the same time respectful of the past history of the buildings.