Seismic Assessment and Retrofitting of an Under-Designed RC Frame Through a Displacement-Based Approach

2017 ◽  
pp. 36-58
Author(s):  
Marco Valente ◽  
Gabriele Milani
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Seismic Assessment ◽  
Original Structure ◽  
Rc Frame ◽  
Existing Structures ◽  
Dynamic Analyses ◽  
Non Linear ◽  
Displacement Based ◽  
Southern European Countries

Many existing reinforced concrete buildings were designed in Southern European countries before the introduction of modern seismic codes and thus they are potentially vulnerable to earthquakes. Consequently, simplified methodologies for the seismic assessment and retrofitting of existing structures are required. In this study, a displacement based procedure using non-linear static analyses is applied to a four-storey RC frame in order to obtain an initial estimation of the overall inadequacy of the original structure as well as the extent of different retrofitting interventions. Accurate numerical models are developed to reproduce the seismic response of the RC frame in the original configuration. The effectiveness of three different retrofitting solutions countering structural deficiencies of the RC frame is examined through the displacement based approach. Non-linear dynamic analyses are performed to assess and compare the seismic response of the frame in the original and retrofitted configurations.

Seismic Strengthening of Non-Ductile R/C Structures Using Infill Wall or Ductile Steel Bracing

2012 ◽  
Vol 602-604 ◽  
pp. 1583-1587 ◽  
Author(s):  
Marco Valente
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Original Structure ◽  
Structural Members ◽  
Infill Wall ◽  
Steel Bracing ◽  
Earthquake Resistant ◽  
Ductile Steel ◽  
Displacement Based ◽  
Nonlinear Dynamic Analyses

This study deals with the seismic assessment and retrofitting of existing non-ductile R/C structures and the issue of selecting effective strengthening solutions is addressed. A displacement based procedure using nonlinear static pushover analyses is adopted in order to assess the main characteristics of the original structure and to select valuable retrofitting strategies. The procedure is applied to a four-storey R/C frame tested at the JRC ELSA Laboratory some years ago. The R/C frame was designed for gravity loads without specific earthquake-resistant provisions. Accurate numerical models are developed to reproduce the seismic response of the R/C frame in both the original and retrofitted configurations. The effectiveness of two strengthening techniques is examined. First, a retrofitting intervention is carried out by adding a concrete shear wall to the short bay of the frame. This solution is efficient in controlling global lateral drift and thus reducing damage in structural members. Then, a retrofitting solution involving the introduction of eccentric steel bracing is investigated in order to reduce the displacement demand and to increase the energy dissipation capacity of the frame. Nonlinear dynamic analyses are performed to assess and compare the seismic response of the frame in the original and retrofitted configurations.

Seismic Assessment of Bell Towers of Mexican Colonial Churches

2010 ◽  
Vol 133-134 ◽  
pp. 585-590 ◽  
Author(s):  
Fernando Peña ◽  
Miguel Meza
Keyword(s):  
Seismic Assessment ◽  
Colonial Period ◽  
Linear Dynamic ◽  
Dynamic Analyses ◽  
Non Linear

The seismic assessment of bell towers of churches built during the colonial period in Mexico is studied. Two representative typologies of churches of the southwest of Mexico are considered. The results of non-linear static and the non-linear dynamic analyses are compared. The results show that it is not recommended the use of non-linear static analyses; being necessary the use of full non-linear dynamic analyses.

scholarly journals An economic solution for stabilising a slender arch roof

1986 ◽  
Vol 19 (2) ◽  
pp. 93-103
Author(s):  
D. D. Spurr
Keyword(s):  
Reinforced Concrete ◽  
Computer Program ◽  
Seismic Response ◽  
Special Study ◽  
Concrete Cracking ◽  
Linear Dynamic ◽  
Earthquake Records ◽  
Dynamic Analyses ◽  
Non Linear ◽  
Prestressing Strand

A special study was made to evaluate the seismic response of the ribs of four reinforced concrete arch aircraft hangars and to assess methods of strengthening the ribs. The study was based on a series of non linear dynamic analyses of the arch ribs, with particular consideration being given to the choice of earthquake records, to the effect of P-delta actions on the arch responses and to the validity of the behaviour predicted by the computer program. The analyses indicated that the arch ribs could become unstable as a result of the P-delta effect acting in combination with reduction in the rib stiffness due to concrete cracking. However, the study also shows that the arches can be stablised very economically by using prestressing strand to provide cross bracing.

Finite element prediction of seismic response modification of monumental structures utilizing base isolation

2015 ◽  
Vol 24 (1-2) ◽  
pp. 59-65
Author(s):  
Konstantinos Spanos ◽  
Nikolaos Anifantis ◽  
Panayiotis Kakavas
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Numerical Models ◽  
Classical Antiquity ◽  
Structural Safety ◽  
Earthquake Activity ◽  
Deformation And Failure ◽  
Non Linear

AbstractThe analysis of the mechanical behavior of ancient structures is an essential engineering task concerning the preservation of architectural heritage. As many monuments of classical antiquity are located in regions of earthquake activity, the safety assessment of these structures, as well as the selection of possible restoration interventions, requires numerical models capable of correctly representing their seismic response. The work presented herein was part of a research project in which a better understanding of the dynamics of classical column-architrave structures was sought by means of numerical techniques. In this paper, the seismic behavior of ancient monumental structures with multi-drum classical columns is investigated. In particular, the column-architrave classical structure under strong ground excitations was represented by a finite element method. This approach simulates the individual rock blocks as distinct rigid blocks interconnected with slidelines and incorporates seismic isolation dampers under the basement of the structure. Sliding and rocking motions of individual stone blocks and drums are modeled utilizing non-linear frictional contact conditions. The seismic isolation is modeled through the application of pad bearings under the basement of the structure. These pads are interpreted by appropriate rubber and steel layers. Time domain analyses were performed, considering the geometric and material non-linear behavior at the joints and the characteristics of pad bearings. The deformation and failure modes of drum columns subject to seismic excitations of various types and intensities were analyzed. The adverse influence of drum imperfections on structural safety was also examined.

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