Anna De Falco

Stability of columns with no tension strength and bounded compressive strength and deformability. Part I: large eccentricity

This work concerns the stability of piles with rectangular cross section, made of a no-tension material with limited compressive strength and deformability, subjected to an axial load acting within the cross section but outside its middle third (large eccentricity). The differential equations obtained have been solved explicitly, and their solutions have allowed us to describe the stability characteristics of the pile through graphical representations.

Structural damage in the cities of Reggiolo and Carpi after the earthquake on May 2012 in Emilia Romagna

This paper addresses the structural damage to the main buildings of the cities of Reggiolo and Carpi after the primary earthquake shocks on May 20th and 29th, 2012, in Emilia Romagna. The damage survey, performed via form-based methods, highlights the different seismic behaviour of several types of buildings, especially those having historical features, and the consequences of the damage in terms of costs. Moreover, an analysis of some failure mechanisms activated in Reggiolo enables the evaluation of the local peak ground acceleration, due to the soil amplification.

Archaeological consolidation of UNESCO masonry structures in Oman: the Sumhuram Citadel of Khor Rori and the Al Balid Fortress

A series of missions, starting from early 2005 up to 2009, have been managed to restore the ancient city walls of Sumhuram(4th century bc to 6th century ad) in the site of Khor Rori, with a group of archaeologists of the University of Pisa. Also, from early 2007, a series of missions have been managed to consolidate the dry masonry Fortress in UNESCO site of Al Balid erected circa 1100 ad with archaeologists of the University of Missouri. Both sites are located in the area of Salalah in southern part of the Sultanate of Oman. The sequence of dry season and rainy season during the Khareef period (Monsoon phenomena) caused several collapses on the excavated masonry structures, with risks for safety of visitors and archaeologists. The walls of Sumhuram, affected by the loss of connection between the two limestone masonry faces, have been rebuilt with the original texture of bricks using a new mix design for mortar joints with the same colors, consistency, and proper strength and durability. The safety level of the consolidation works is evaluated by observing on site the shape of the collapse surfaces and using the classical limit analysis approach. The collapses of Al Balid dry masonry walls have been originated by the loss of permeability of the external wall faces due to the progressive filling of joint by soil. Consolidation activities consisted of rebuilding with the same blocks down and substituting the earth behind the external layers with gravel and high permeability filling. An analytical model of dry rigid block masonry with frictional interfaces has been used to represent the out-of-plane behavior, in order to define the maximum height of excavation and the maximum free height of the restored walls to guarantee safety for workers.

Structural Analysis and Consolidation Strategy of the Historic Mediceo Aqueduct in Pisa (Italy)

The present work assesses the state of conservation of the historical Mediceo Aqueduct in Pisa, with classification of architectural elements, decay of materials and failures in view of the restoration. The preview of collapses and the design of interventions in a significant part of the aqueduct are performed. New masonry buttresses for the entire path with optimal distribution are determined to ensure safety and integrity to the monument.

Temporary Preventive Seismic Reinforcements on Historic Churches: Numerical Modeling of San Frediano in Pisa

The idea to apply temporary and precautionary seismic reinforcements to protect artistic assets in historical buildings is hereby presented. The example of the San Frediano Church in Pisa is addressed to show the improvements in its seismic response due to steel wire ropes applied to arches and columns. Numerical analysis demonstrate the reduction of the shear force at the base of the stone columns. The proposed reinforcements are reversible, temporary and with low aesthetic impact: they can be quickly installed in the beginning of seismic events, as an evolution of the techniques adopted after the last Italian earthquakes (Abruzzo 2009 Emilia 2012).

Collapse of the Historic City Walls of Pistoia (Italy): Causes and Possible Interventions

In the paper are discussed the likely causes of the collapse and the temporary safety features adopted to secure a collapsed portion of the Historic Walls of the city of Pistoia (Italy). The walls of medieval origin, affected by various subsequent modifications and alterations, have been subjected to a sudden collapse, after a period of heavy rain, for a length of about 25 meters. Hereby are described the probable causes of the collapse, due to a poor quality of the walls (external façades with external layer made up of river pebbles and inner filling material in-coherent), height of building is not modest (approximately eleven meters), a significant differential in height between the two faces (about four meters) and a not unlikely rotation of the base. It is proposed a technique of temporary reinforcement with a system of steel tie-beams and braces with a view to the work of reconstruction of the partially collapsed and consolidation of the lateral parts of wall.

Legal Disputes and Building Defects: Data from Tuscany

AbstractThis paper reports on a wide-ranging study conducted on the interim technical assessments (ITAs) drawn up for lawsuits over defective constructions in Tuscany, Italy, from 2000 to 2011. It provides a set of statistically significant data to highlight the impact of construction defects in buildings and evaluate their origins and the responsibilities of the technical personnel involved. The data have been classified according to various categories based on the type of damage encountered. Analysis of the most common types (in particular, water damage) and comparisons with the data from a similar survey carried out in 1990–1999 provide indications as to the critical aspects deserving of special attention, including building design and inspections during construction. Such analysis can provide useful information for assessing whether the quality of construction has kept pace with new knowledge and advances in technology.

A Proposal for the Consolidation of a R.C. Social Housing by Means of External Hybrid Steel-Glass Frameworks

A proposal for the seismic consolidation of an existing r. c. social housing complex is presented. The intervention is thought to concern just the external facades in order to minimize costs and discomfort of inhabitants. Two external hybrid steel-glass bracing frameworks have been designed, with the aim to reach both seismic and energetic advantages. The mechanics of the framework system takes advantages from the compressive strength of the glass panels and the tension strength of steel braces and columns. A hypothetical application on a typical r. c. building dating back to the ‘60s in the city of Leghorn (Italy) is illustrated.

An Innovative Low Cost Solution for Bamboo Trusses with High-Ductility Connections

Innovative solutions of bamboo connections and an application on Polonceau trusses to use for simple constructions are presented. Experimental tests show the performances and the high level of ductility of the proposed technique, joined with simplicity, with low-level of technology and low cost of all used materials. Their applications with sustainable maintenance are suitable in developing countries.

Structural Solutions for Low-Cost Bamboo Frames: Experimental Tests and Constructive Assessments

Experimental tests and constructive assessments are presented for a simple bamboo framed structure with innovative low-cost and low technology joints, specifically conceived for small buildings in developing countries. Two full scale one-storey bamboo frames have been designed by using the simplest joints solution among three different tested typologies. The entire building process is based on low-technology and natural materials: bamboo canes, wooden cylinders, plywood plates and canapé rods. The first full scale specimen (Unit A) is a one-storey single deck truss structure subjected to monotonic collapse test; the second full scale specimen (Unit B) is a one-storey double deck truss structure used to evaluate the construction time throughout assembling tests. The first full scale specimen showed ductility in collapse and ease in strengthening; the second one showed remarkable ease and speed in assembling structural elements. Finally several constructive solutions are suggested for the design of simple one-storey buildings; they are addressed to four purposes (housing, school, chapel, health center) by the composition of the proposed full scale bamboo frames. Ease of use and maintenance with a low level of technology contribute to application in developing countries although not exclusively.