Out-of-plane buckling instability limit state for boundary regions of special RC structural walls

2019 ◽  
Vol 17 (9) ◽  
pp. 5159-5182 ◽  
Author(s):  
A. G. Haro ◽  
M. Kowalsky ◽  
Y. H. Chai
Keyword(s):  
Limit State ◽  
Structural Walls ◽  
Buckling Instability ◽  
Out Of Plane ◽  
Rc Structural Walls

Large-Scale Resonant Fatigue Testing of Welded Tubular X-Joints for Offshore Jacket Foundations

2019 ◽  
Author(s):  
Jeroen Van Wittenberghe ◽  
Philippe Thibaux ◽  
Maarten Van Poucke
Keyword(s):  
Large Scale ◽  
Fatigue Testing ◽  
Water Pressure ◽  
Limit State ◽  
Fatigue Tests ◽  
Offshore Wind ◽  
Design Standards ◽  
Initiation Phase ◽  
Out Of Plane ◽  
Jacket Structures

Abstract Offshore wind turbines are being installed in deeper water and with more powerful generators resulting in more severe loading conditions on its foundations such as jacket structures. Because the main loading is due to wind and currents, the dominant design limit state is fatigue. The fatigue performance of the tubular joints used in jacket structures has been assessed several decades ago based on test results with limited component dimensions (diameter and wall thickness). In addition, improvements of welding methods and evolution of steel grades are not considered in the current design standards. To provide experimental fatigue-life data on large-scale structures a test program has been carried out on 4 welded tubular X-joints. Each X-joint consists of two horizontal braces with a diameter of 711 mm welded to a central vertical tubular member with 806 mm diameter. The X-joint has a total length of 7.5 m and has two identical welds that are fatigue tested. The fatigue tests are carried out on an innovative resonant bending fatigue test rig that allows to load the specimen in in- and out-of-plane direction at a different amplitude to obtain an even stress distribution over the circumference of the welds. The tests are carried out at a speed close to the resonance frequency of the X-joint. During the test, hotspot strains are measured using strain gauges and a limited amount of water pressure is used to detect through-thickness cracks. The tests are carried out in two phases. During the crack initiation phase, the sample is loaded in both the in- and out-of-plane mode. Once cracks are detected, the test is continued in the crack propagation phase with loading in the plane where cracks had been initiated until through-thickness cracking appeared. During this phase the beach marking technique has been used to mark the shape of the fracture surface at different moments during the fatigue tests. The testing program is part of the RFCS project JABACO that aims to reduce offshore wind cost by incrementing prefabrication of the jacket substructure.

A parametric study on out-of-plane instability of doubly reinforced structural walls. Part II: Experimental investigation

2020 ◽  
Vol 18 (11) ◽  
pp. 5193-5220
Author(s):  
Farhad Dashti ◽  
Mayank Tripathi ◽  
Rajesh P. Dhakal ◽  
Stefano Pampanin
Keyword(s):  
Experimental Investigation ◽  
Parametric Study ◽  
Structural Walls ◽  
Out Of Plane

Seismic response of structural walls: recent developments

2001 ◽  
Vol 28 (6) ◽  
pp. 922-937 ◽  
Author(s):  
T Paulay
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Seismic Design ◽  
Limit State ◽  
Lateral Force ◽  
Structural Walls ◽  
Structural Class ◽  
Response Component ◽  
Displacement Ductility ◽  
Ductility Capacity

It is postulated that for purposes of seismic design, the ductile behaviour of lateral force-resisting wall components, elements, and indeed the entire system can be satisfactorily simulated by bilinear force–displacement modeling. This enables displacement relationships between the system and its constituent components at a particular limit state to be readily established. To this end, some widely used fallacies, relevant to the transition from the elastic to the plastic domain of behaviour, are exposed. A redefinition of stiffness and yield displacement allows more realistic predictions of the important feature of seismic response, component displacements, to be made. The concepts are rational, yet very simple. Their applications are interwoven with the designer's intentions. Contrary to current design practice, whereby a specific global displacement ductility capacity is prescribed for a particular structural class, the designer can determine the acceptable displacement demand to be imposed on the system. This should protect critical components against excessive displacements. Specific intended displacement demands and capacities of systems comprising reinforced concrete cantilever and coupled walls can be estimated.Key words: ductility, displacements, reinforced concrete, seismic design, stiffness, structural walls.

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