Paolo Riva | Università degli Studi di Bergamo (University of Bergamo) (original) (raw)

Papers by Paolo Riva

European Journal of Environmental and Civil Engineering, 2017

In this paper, an integrated approach targeting sustainability, safety, and resilience is envisio... more In this paper, an integrated approach targeting sustainability, safety, and resilience is envisioned for the renovation of the post-World War II RC buildings clustered in urban outskirts. The solution stems as an enhancement of the widespread camouflage practice, which targets energy efficiency and architectural restyling by complementing the building with a technological double skin, self-supported on an independent exoskeleton. Based on this integrated approach, the exoskeleton can be further engineered to also enable structural safety and resilience. Life cycle thinking is addressed to re-conceive traditional structural design approaches, guaranteeing safety, while minimizing costs and environmental impacts over the building life cycle. Accurate selection of materials and dry technologies enables adaptability, reparability and maintenance, and total recyclability/reuse at end-of-life. The intervention is carried out from outside, avoiding relocation of the inhabitants and possible building downtime. The paper introduces a possible framework for engineers, technologists, and architects to design new holistic renovation interventions, for which innovative solution sets are required. Possible structural techniques to be coupled with energy refurbishment are proposed. As a proof of concept, the envisaged holistic renovation strategy is applied to a reference building, and benefits entailed in combining structural safety measures within an integrated intervention are commented.

Sommario La valutazione della capacità degli edifici di sopravvivere agli effetti indotti da un e... more Sommario La valutazione della capacità degli edifici di sopravvivere agli effetti indotti da un evento sismico è da sempre uno dei temi che maggior-mente ha preoccupato i progettisti, in relazione soprattutto alle conseguenze che si possono avere sull'incolumità degli occupanti (stato limite di salvaguardia della vita come definito al Punto 3.2.1 del D.M. 14 Gennaio 2008). In particolar modo, per quanto concerne gli edifici prefabbricati, questa valutazione è resa ancor più difficoltosa a causa delle differenze di tipo-logia e materiali fra gli elementi prefabbricati (primari e secondari) e i meccanismi che realiz-zano le connessioni fra gli elementi stessi. Per quanto concerne il territorio nazionale, le strutture prefabbricate sono generalmente desti-nate al settore industriale: sembra quindi sen-sato porre in evidenza il fatto che ripercussioni sociali ed economiche potenzialmente elevate possono essere provocate da situazioni di ina-gibilità e di interruzioni delle attività,...

International Journal of Architectural Heritage, 2015

This article reports the results of a research study on the behavior of injected anchors in histo... more This article reports the results of a research study on the behavior of injected anchors in historical masonry under cyclic loads. Laboratory tests with masonry specimens (bricks and mortar with low characteristics to replicate real historical masonry) were conducted to analyze the response of steel anchors injected using a special sock and with different types of mortar (cement and lime based). The test benches replicate the real condition of the use of these anchors: they allow simulation of the connection of masonry panels (T and L connections) or the anchor of steel ties to contrast the arch thrust. Monotonic and cyclic pullout tests were conducted on short and long anchors to define the loss of strength under cyclic loads for different situations. The results yielded load-displacement graphs, steel bar deformation graphs of the anchors’ length, a qualitative bond stress curve, and a comparison among maximum strengths obtained under several conditions.

The refurbishment of the existing building stock is nowadays becoming a priority in order to meet... more The refurbishment of the existing building stock is nowadays becoming a priority in order to meet energy-saving and emission-control international targets and to foster safety and resilience of European communities. A new research recently introduced the concept of holistic seismic, energy, and architectural renovation of existing buildings targeting resilience, safety, and sustainability. Integrated retrofitting techniques have been proposed, and a new structural design procedure has been studied rethinking existing approaches by including sustainability principles. With reference to post-WWII RC buildings, which are often mid-rise isolated buildings located at the city outskirts, additional exoskeletons implementing the technologies and devices for an integrated upgrade have been proposed. Exoskeletons are entirely built from outside, thus avoiding the temporary dismissal of the buildings and the relocation of the inhabitants. Both ‘shear wall’ or ‘shell’ solutions, either dissipa...

The paper investigates the suitability of grouted sleeve connections as column-to-foundation conn... more The paper investigates the suitability of grouted sleeve connections as column-to-foundation connections for precast concrete structures in seismic regions. Al-though grouted sleeves are commonly used, the typical advantages from this connection have not been fully addressed in the literature.Experiments on the cyclic behavior of column-to-foundation subassemblies compared the response of grouted sleeve connections with cast-in-place and pocket-foundation connections. The results demonstrate that grouted sleeves ensure a ductility and energy dissipation capacity similar to those of traditional connections. The confinement provided by the grouted sleeves inhibits buckling of the longitudinal reinforcement and increases the compressive strength of the grout. As a consequence, the damage associated with this kind of connection is localized to the column base, allowing easier postseis-mic column repair compared with traditional connec-tions. The comparison of the experimental response o...

The reinforced concrete constructions built after World War II represent almost half of the Europ... more The reinforced concrete constructions built after World War II represent almost half of the European building stock. Such buildings are characterized by low energy efficiency, living discomfort and may be inherently vulnerable to seismic actions, having been designed before the enforcement of modern building codes. A global integrated intervention for the sustainable restoration of the considered building stock is proposed in this paper. The conceived approach overcomes the shortcomings of the traditional renewal practice, targeting uncoupled solution of single deficiencies. The solution also stems as an enhancement of past pioneering techniques, such as the double skin, focusing on architectural restyling and energy efficiency upgrade. In the proposed approach energy efficiency and structural upgrading measures are coupled, and the exoskeleton is complemented with ad-hoc systems and devices to increase structural safety and seismic resilience. The intervention is carried out from t...

New concepts, applications and challenges, 2013

Le costruzioni in cemento armato rappresentano circa il 50% del patrimonio edilizio esistente, re... more Le costruzioni in cemento armato rappresentano circa il 50% del patrimonio edilizio esistente, realizzato soprattutto durante la seconda metà del ventesimo secolo. Tali edifici hanno esaurito la loro vita utile (50-60 anni secondo gli attuali standrard normativi) e presentano carenze sia dal punto di vista strutturale che energetico, inoltre la loro gestione in termini di impiego di risorse energetiche risulta essere poco sostenibile. L'articolo in oggetto rappresenta un tentativo di risposta al recupero di questo patrimonio edilizio mediante soluzioni integrate a doppio involucro finalizzate alla riqualificazione strutturale, energetica ed architettonica degli edifici e alla valorizzazione dei relativi contesti urbani. La tecnica di intervento è proposta come soluzione per un caso studio di riferimento, applicabile a tutti gli edifici di scarsa qualità architettonica appartenenti alle tipologie edilizie tipiche del secondo dopoguerra, e modulabile in funzione del contesto geografico, urbanistico e climatico, nonché in base alla pericolosità sismica. La soluzione si pone come alternativa ai tradizionali interventi di demolizione e ricostruzione, o alla riqualificazione solo architettonica ed energetica. Parole chiave: Riqualificazione sostenibile edifici esistenti, doppio involucro strutturale-tecnologico, edifici in c.a. del secondo dopoguerra, miglioramento e adeguamento sismico, approccio integrato strutturaenergia.

Beam-to-column joints are commonly considered critic regions for r.c. frames subjected to high-ma... more Beam-to-column joints are commonly considered critic regions for r.c. frames subjected to high-magnitude earthquakes. When designed for gravity loads only, beam-to-column corner joints can not only strongly affect the global structural behaviour of a frame, but also be a cause of its collapse. In the paper a component-based f.e. model of external beam-to-column joints is presented. The joint deformation is modelled by means of two unrelated contributions, the shear deformation of the panel zone, and the rotation at the interface sections between the joint and the structural members, due to the reinforcing bars’slip within the joint core. The first part of this work focuses on the evaluation of the joint strength and stiffness. Finally, the component-based f.e. model is validated by experimental results of tests on beam-column corner joint realized according the construction practice of the 60’s-70’s, confirming the effectiveness of the presented model for the assessment of existing structures.

Engineering Structures, 2015

ABSTRACT Beam-to-column joints are commonly considered critic regions for RC frames subjected to ... more ABSTRACT Beam-to-column joints are commonly considered critic regions for RC frames subjected to earthquake actions. When designed for gravity loads only, beam-to-column corner joints strongly affect the global structural behaviour of a frame, and they can be cause of its collapse, as shown by recent earthquakes in Europe. In the paper, a component-based f.e. model for external beam-to-column joints is presented to simulate the seismic behaviour of r.c. existing structures designed without any capacity design criteria (smooth bars with hooked-end anchorages and with no transverse reinforcements in the joint). The joint deformation is modelled by means of two separate contributions, the shear deformation of the panel zone, and the rotation at the interface sections between the joint and the structural members, due to the reinforcing bars’ slip within the joint core. The work focuses on the evaluation of the joint strength and stiffness, and it points out the importance of modelling the bar bond slip within the panel zone to describe the actual frame response. The component-based f.e. model is validated by experimental results of tests on beam-to-column corner joints realized according to the construction practice of the 1960s– 1970s in Italy, thus confirming the effectiveness of the presented model for the assessment of existing structures.

European Journal of Environmental and Civil engineering, 2011

This paper aims at presenting the results of two experimental tests concerning the cyclic behavio... more This paper aims at presenting the results of two experimental tests concerning the cyclic behaviour of a dissipative column-to-foundation connection for precast concrete elements. The tested joints are characterized by the use of high strength threaded steel bars partially un-bonded in grouted sleeves and by steel support elements which allow an easy assemblage and centering of the column. The two

Materials and Structures, 2005

Abstract The possibility of substituting traditional transverse reinforcement (stirrups) for stee... more Abstract The possibility of substituting traditional transverse reinforcement (stirrups) for steel fibres in precast elements can significantly reduce production costs. In the present paper, the shear behaviour of prestressed elements has been investigated by means of experimental ...

Materials and Structures, 2004

... design. 2. NUMERICAL MODELS Numerical analyses were performed by adopting two commercial FE p... more ... design. 2. NUMERICAL MODELS Numerical analyses were performed by adopting two commercial FE programs, MERLIN [14] and DIANA [15], for the discrete crack and smeared crack approach, respectively. MERLIN considers ...

Magazine of Concrete Research, 2002

ABSTRACT

Applied Mechanics and Materials, 2011

The possibility of strengthening existing R/C structures with a new technique based on the applic... more The possibility of strengthening existing R/C structures with a new technique based on the application of a High Performance Fiber Reinforced Concrete jacket is investigated herein, with the aim of studying the effectiveness of this technique for seismic retrofitting. The results of a beam-column joint full scale test simulating the behavior of existing beam-column joints are presented. The specimen have been subjected first to static loads and after to cyclic actions with increasing amplitude, up to failure. The tests demonstrated that, with the application of a HPFRC jacket, it was possible to remarkably increase the bearing capacity of the columns reaching also an adequate level of ductility, and the resistance of the beam column joints, with very little visible damage, thanks to the tensile strength contribution of HPFRC.