BrainMap

Ovidiu Abrudan

Eng

- UNIVERSITATEA POLITEHNICA TIMIŞOARA

Technician

Expertise & keywords

Implementation into Romanian seismic resistant design practice of buckling restrained braces Call name: Joint Applied Research Projects - PCCA 2013 - call
PN-II-PT-PCCA-2013-4-2091 2014 - 2017

Role in this project:

Coordinating institution: UNIVERSITATEA POLITEHNICA TIMIŞOARA

Project partners: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO); POPP & ASOCIATII S.R.L. (RO); HYDROMATIC SISTEM SRL (RO)

Affiliation: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO)

Project website: http://www.ct.upt.ro/centre/cemsig/imser.htm

Abstract:

The latest version of the Romanian seismic design provisions (P100-1/2013) have introduced, for the first time in Europe, design provisions for buckling restrained braced (BRB) frames.

Buckling restrained braces have a great potential in the field of seismic design of structures due to their large ductility and symmetrical cyclic response, as compared with conventional braces. They can be used both for new construction, as well as for strengthening of existing reinforced concrete, steel or masonry structures. BRB frames are able to provide two key properties of a seismic resistant structure: stiffness (for reducing interstorey drifts under moderate earthquakes) and ductility (for energy dissipation capacity under large earthquakes). BRBs were studied extensively worldwide over the past 30 years and have many practical applications especially in Japan and United States. Though researched in Europe as well, BRBs were applied in a very few applications here. The main reasons for lack of application into practice are believed to be the absence of design provisions in EN 1998-1, not enough acquaintance with the system by practising structural engineers, need for experimental validation (which increases project budget and completion schedule), and proprietary character of most BRB devices.

The project aims at clearing the way for a rapid adoption of the BRBs into design practice by solving the problems highlighted above, through the following actions:

- Development of two different types of BRB prototypes: "conventional" (steel core / mortar / steel casing) and "dry" (without mortar), followed by a prequalification testing program on a set of BRBs of different capacity. This will provide an initial database on prequalified BRBs, rendering project-specific experimental programs unnecessary, at least for most common design situations.

- Transfer of the "know-how" on design and production of two types of BRBs to the industrial partner, who will be able to set up quantity production of these devices.

- Development of design guidelines for buckling restrained braces (at the device level). It will allow production of generic BRBs by local producers at more competitive prices than imported ones. "Dry" (or "steel-only") BRBs are believed to be especially suited for this purpose, as they can be easily adopted by steel fabricators.

- Development of design guidelines and design examples for steel BRB frames (at system level). This will make the new system more appealing to practicing engineers.

- Disseminate the project outcomes to practising engineers, through presentations in annual conferences of the Association of Structural Engineers (AICPS) and through two workshops organised in Bucharest and Timisoara.

The project is built on the partnership among three important actors in the construction industry: a research organisation (Politehnica University of Timisoara), a designer (SC Popp & Asociatii SRL) and a fabricator (SC Hydromatic Sistem SRL). This collaboration allows the problem to be addressed in a systematic and holistic manner, paving thus the way of the innovative product (steel buckling restrained braces) from research to practice.

Seismic protection of engineering structures through dissipative braces of nano-micro magnetorheological fluid dampers Call name: Joint Applied Research Projects - PCCA 2013 - call
PN-II-PT-PCCA-2013-4-1656 2014 - 2017

Role in this project:

Coordinating institution: UNIVERSITATEA POLITEHNICA TIMIŞOARA

Project partners: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO); ROSEAL S.A. (RO); INSTITUTUL DE MECANICA SOLIDELOR (RO); ACADEMIA ROMANA FILIALA TIMISOARA (RO); TITAN ECHIPAMENTE NUCLEARE SA (RO)

Affiliation: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO)

Project website: http://www.ct.upt.ro/centre/cemsig/semnal-mrd.htm

Abstract:

There are three strategies that can be used for seismic protection of structures: 1) reduce seismic demands; 2) enhance structural damping and 3) use active or semi-active structural control. Present project is framed in the third strategy focusing on semi-active systems. A semi-active device has properties that can be adjusted in real time but cannot inject energy into the controlled system. Many of them can operate on battery power alone, proving advantageous during seismic events when the main power source to the structure may fail. One of the most promising devices suitable for implementation into a semi-active control appears to be magneto-rheological (MR) dampers, which succeed in overcoming many of the expenses and technical difficulties associated with other types of semi-active devices. Response characteristics of magneto-rheological devices can be changed by varying the magnetic field through different current inputs. In addition to its small power requirement, the MR damper can generate large forces at low velocities. Currently there are MR dampers with capacities up to 200 kN and research results proved the possibility to obtain capacities up to 400-500 kN.

Present project intends to apply the nano-micro composite magnetizable fluids (MRF), whose properties may be tailored for the use in semi-active MR devices, with expectation to obtain appropriate and easy controllable performance for seismic protection applications, characterized by random low frequency motions of significant amplitudes. Previous experience (patents) of partners in the project consortium on using this technology to produce high pressure rotating seals already exists and offers a good starting base for present application. The possibility of fine tuning of the magneto-rheological response is a highly attractive feature of the nano-micro composite MR fluids, and that will be fully investigated and exploited. The MR response is dependent on the mean size and volume fraction of multi-domain ferromagnetic particles, but also on the volume fraction (saturation magnetization) of the magnetic nano-fluid carrier. The parameters of composition ensure manifold controlling mechanisms of the MR behavior of the nano-micro MR fluids and their fine tuning to the requirements of the envisaged MR damping devices for seismic protection of structures under different seismic motion characteristics. One MR damper of low capacity will be designed, fabricated and tested under different loading conditions (triangular, sinusoidal and random excitations). Numerical hysteretic models will be calibrated on the tested MR damper enabling modeling of structural response. Since the dampers in structural systems will be installed coupled with braces, both single damper and brace-damper assembly tests will be performed. With a numerically simulated control unit, structural systems equipped with brace-damper assemblies will be numerically tested in order to observe and characterize their behavior. The main outcomes of the project are: 1.Micro-nano composite MR fluid recipes for seismic semi-active dampers ; 2.Technical solutions for MR dampers; 3. A 10t MR damper prototipe; 4.Validation tests of brace-damper systems; 5.Numerical evaluation of effectiveness of MR dampers in reducing seismic effects in structural applications. Some of these results ((1) and (2)) might be patented. Moreover, the project will develop and provide an implementation plan, with the further research needs and technological developments aiming at implement in the current fabrication the MR nano-fluid dampers by the industrial partners. A consortium composed by two research centers of PU Timisoara, two research institutions of Romanian Academy, experienced in seismic engineering, complex ferro-fluid applications and structural control, and two industrial partners, with experience and capabilities for fabrication of MR fluids and dampers will be able to achieve the objectives of the project.

Structural conception and COllapse control performance based DEsign of multistory structures under aCcidental actions Call name: Joint Applied Research Projects - PCCA-2011 call, Type 2
PN-II-PT-PCCA-2011-3.2-1303 2012 - 2016

Role in this project:

Coordinating institution: UNIVERSITATEA POLITEHNICA TIMIŞOARA

Project partners: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO); UNIVERSITATEA TEHNICA CLUJ ACTIVITATE ECONOMICA (RO); INSTITUTUL NATIONAL DE CERCETARE-DEZVOLTARE IN CONSTRUCTII, URBANISM SI DEZVOLTARE TERITORIALA DURABILA "URBAN-INCERC" (RO); INSTITUTUL NAŢIONAL DE CERCETARE - DEZVOLTARE PENTRU SECURITATE MINIERĂ ŞI PROTECŢIE ANTIEXPLOZIVĂ - INSEMEX PETROŞANI (RO); ACI CLUJ S.A. (RO)

Affiliation: UNIVERSITATEA POLITEHNICA TIMIŞOARA (RO)

Project website: http://www.ct.upt.ro/centre/cemsig/codec.htm

Abstract:

The development of design guides for collapse control of the multi-story buildings started in 1968 with the collapse of the Ronan Point high-rise building in the United Kingdom, due to a gas explosion. The failure of the building was identified as a "progressive collapse", because the extent of damage was disproportionate compared to the initial cause. Three decades later, in 2001, the attack against the twin towers of the World Trade Center caused the complete failure of the two buildings and massive loss in lives and property. The type of collapse was again identified as progressive collapse. More recently, during the winter 2005/2006, several construction halls, shopping centers or hotels have been damaged or destroyed throughout Europe due to very heavy snowfalls. The concept of collapse control design can be considered the most appropriate approach for preventing the progressive collapse in case of extreme load events. In principle, the collapse control design method assesses and improves the redundancy of buildings by assuming the loss of structural members such as columns and beams due to extreme accidental loads and assessing how many members might be lost until the entire collapse of the building. The main objective of the project is the development of a performance based robustness design methodology for mitigation the progressive collapse of multi-story frame buildings against extreme load events, coming from both natural and man-made hazards. On this purpose, the research project will aim at definition, evaluation and modeling of the hazards, development of models for characterization of the material properties under different conditions, methods for structural evaluation and intervention strategies for mitigating the probability of collapse in case of extreme load events. All these subjects have a significant innovative character for actual state of knowledge and codification in Europe. As output, design criteria, numerical models, acceptance criteria.

FILE DESCRIPTION	DOCUMENT
List of research grants as project coordinator or partner team leader
Significant R&D projects for enterprises, as project manager
R&D activities in enterprises
Peer-review activity for international programs/projects