Seismic analysis of structural and industrial plant components

The HMSDC group has been actively conducting research in the area of seismic analysis and design of structural and mechanical components/systems of industrial plants. The research is driven primarily by two needs: (i) on one hand, we aim at utilizing high strength steel circular hollow sections that are still limited in the construction industry, despite of their excellent properties with regard to load-bearing capacity, their attractive shapes in appearance and the fast development of relevant manufacturing processes; (ii) on the other hand, we intend to exploit performance-based earthquake engineering design methodologies, in order to safeguard the integrity of industrial equipment and steel structures like liquid storage tanks, pressure vessels and piping systems under seismic loadings. The application area of this research considers the conceptual analysis and design of structural components subjected to earthquake loadings. It also comprises analysis techniques both based on first principles and advanced finite element software to optimize the performance of structural components.

For example, the group is working on performance-based earthquake analysis and design of petrochemical piping systems and their components, such as flange joints, tee joints, elbows, valves, pressure vessels and storage tanks, which are highly important for the energy industries to transport goods like oil and gas across the world. Recent reports showed that piping systems are quite vulnerable to earthquakes and catastrophic damages occurred as a results of their failure under seismic events. Relevant research of the HMSDC group focuses on exploiting performance-based earthquake engineering design methodologies to safeguard the integrity of piping systems and their components under seismic loadings. 

The group was part of the European Union research project INDUSE: “Structural Safety of Industrial Steel Tanks, Pressure Vessels and Piping Systems under Seismic Loading” (Grant No. RFSR-CT-2009-00022), within which it conducted experimental and numerical investigations to evaluate seismic performance of a petrochemical piping systems and their components. In a greater detail, a novel ductile bolted flange joint was designed for enhanced seismic performance and their validity was justified through cyclic bending and axial cyclic testing; see Fig. 1. In addition, a full-scale petrochemical piping system was experimentally tested under earthquake loading by means of modern hybrid experimental techniques, namely pseudo-dynamic and real-time testing; see Fig. 2.

Furthermore, recently the group participated in a European Union research project SEQBRI (Contract RFSR-CT 2012-00032) to develop a Performance-Based Earthquake Engineering (PBEE) methodology applied to short-medium span steel -concrete composite I-girder bridges made of hot rolled fine grain steel beams –see Fig. 3- that includes seismic input randomness, probabilistic demand evaluation and damage analysis as well as economic cost-benefit estimations. It was based on the premise that performance could be predicted and evaluated with confidence to make, together with clients, intelligent and informed trade-offs based on cost-effective risk management rather than design and construction costs alone.

The experimental activities carried out in collaboration with UNIROMA3 investigated the damaging of novel bridge details under seismic action. Crucial point of PBEE is the relation between Engineering Demand Parameters (Drift, Rotation, etc.) and Damage Measures; in order to cover a wide range of Engineering Demand Parameters both transversal and longitudinal action was considered. The experimental campaign included monotonic and cyclic tests in two directions was designed (experimental set-up, history of displacement) in accordance to the code and validated with some numerical nonlinear dynamic simulations. Relevant experimental set-up and specimens are shown in Fig. 4 and 5, respectively, whereas, numerical responses are shown in Fig. 6 and 7.

   

 
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Fig.1 (a) Four-point bending test set-up of a bolted flange joint; (b) relevant cyclic response of the joint
Fig. 2 (a) Experimental set-up of a piping system under seismic loading; (b) relevant strain history in an elbow.

                                                  

                                             Fig. 3 Steel-concrete composite bridge with hot-rolled profiles.

                   

 

 

 

Fig 4 3D view of transversal test set-up                                                                                       Fig 5. Steel I-girder of deck subassembly 

 

 

 

 

 

 

 

 

Fig.6 Pier drift and shear deformation results of non linear time history simulation 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig 7 Incremental Dynamic Analysis of 14 different ground motions, scaling criteria Sa (T1).