Life-cycle cost analysis for an incremental seismic rehabilitation project

Incremental seismic rehabilitation (ISR) consists of a set of discrete rehabilitation actions in order to decrease initial costs and to avoid long-lasting disruptions. Nevertheless, there are few cases of incrementally retrofitted buildings and few studies about its economic feasibility. The objective of this work is to evaluate the differences between incremental and single-stage rehabilitation in terms of economic losses during the building’s life span. For this purpose, this work analyzes three rehabilitation proposals to improve seismic performance of typical school buildings. Based on P58 FEMA (Federal Emergency Management Agency) methodology, expected repair costs and benefits were calculated for each rehabilitation intervention. Results confirm the potential of ISR for improving essential buildings.

Integrated Solution-Base Isolation and Repositioning-for the Seismic Rehabilitation of a Preserved Strategic Building

This paper deals with the design of the seismic rehabilitation of a case-study building located in Florence, Italy. The particular reinforced concrete building hosts an important operational center of the main company that manages the Italian highway network. It is composed of the juxtaposition of three reinforced concrete edifices standing out from a common basement. The design of the interventions for the seismic rehabilitation of this case study posed different challenges, some even in contrast with each other. The main design challenge was to reach the seismic retrofitting, due to the strategic role of the activities hosted herein, safeguarding as much as possible the peculiarity of the architectural elements. Moreover, the design was made harder by the presence of existing thermal joints between adjacent edifices which were inadequate to prevent the latter from pounding upon each other during an earthquake. This outcome yielded the need to intervene by enlarging the gap between the adjacent buildings. This latter intervention was in stark contrast with the explicit request of the client to bring the least possible disturbance to the strategic activities carried out within it; in fact, the joints are crossed by optical fibers and other technological systems which can be damaged easily. The need to fulfill all these design constraints brought the development of an original design strategy based on the employment of base-isolation in a rather unusual configuration. The details of the design procedure, along with the innovative aspects and the designed devices, are presented. With the objective to refine the adopted strategy in view of its possible repeatability by colleague engineers, the paper also presents a fair discussion of every aspect with regards to both the design and the realization phases. Possible ideas for new research and developments are also highlighted.

The High-Performance Dissipating Frame (HPDF) System for the Seismic Strengthening of RC Existing Buildings

In Italy as well as in other earthquake-prone countries, the large number of existing buildings requiring seismic retrofitting calls for sustainable solutions able to reduce both costs and downtime. To this purpose, in this paper, the High-Performance Dissipating Frame system (HPDF), a new strengthening solution for the seismic rehabilitation of existing buildings, is presented. HPDF is based on external precast reinforced concrete (RC) frames rigidly connected to the existing structures and equipped with shear damper devices in order to provide high dissipation capacity. The proposed solution permits: (i) to increase sustainability through works made up from the outside without removing/demolishing infills/other non-structural components, (ii) rapid execution by adopting precast resisting members mutually restrained with steel connections, and (iii) effectiveness due to shear damper devices able to dissipate a large amount of shaking energy. In the paper, a displacement-based design procedure is proposed and applied to a numerical example.

Seismic rehabilitation of concrete buildings after the 1985 and 2017 earthquakes in Mexico City

The 19 September 2017 Puebla–Morelos earthquake provides a unique opportunity to (a) study the effectiveness of seismic rehabilitation methods implemented in Mexico City after 1985 and (b) collect large amounts of data on current building rehabilitation practices. This article presents and discusses seismic rehabilitation efforts conducted on concrete buildings after the 1985 and 2017 earthquakes. Building damage and vulnerabilities, code provisions for rehabilitation, and common repair and retrofit techniques used in these two periods of time are summarized. The performance of four buildings rehabilitated after 1985 is examined based on results from field investigations conducted after the 2017 event. These rehabilitations were effective in improving the performance of these buildings according to observed damages and estimated shaking intensities. To allow a more systematic assessment of seismic rehabilitations in future earthquakes, an inventory of rehabilitated buildings in Mexico City is currently under development. Preliminary data obtained from this inventory effort are presented and discussed.