Experimental determination of the rotational capacity of wall-to-base connections in storage tanks

Cortes, Gustavo; Nussbaumer, Alain; Berger, Christian; Lattion, Eric

doi:10.1016/j.jcsr.2011.02.010

Cited by 17 publications

(24 citation statements)

References 8 publications

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“…3(b). The specimens have a base-plate length of 105 mm (145 mm shorter than the specimens tested in [7,8]), and base-plate thickness of 12 mm (compare with 6 mm in [8] shell length are consistent between the three experimental studies. All specimens containing radial welds are tested with the weld backingbar (a strip of metal placed under the base-plate during welding) still intact.…”

Section: Test Overviewsupporting

confidence: 61%

“…Note that the tank connection specimen is rotated 90°such that the base-plate is parallel with the vertical actuator. To help transfer the base-plate tensile load into the strong floor and prevent plastic hinge formation in the tank shell, a portion of base-plate extending beyond the tank shell is welded to the self-leveling frame (similar to the testing by [7,8]). …”

Section: Test Overviewmentioning

confidence: 99%

“…Due to this 150 mm stroke limitation and a chosen peak base-plate rotation range of 0.4 rad, the specimen base-plate length had to change from the previous geometries used in [7,8]. This test modification is described in detail in the next section.…”

Section: Test Overviewmentioning

confidence: 99%

“…1 shows a typical tank assembly, with the tank base having multiple pentagonal sections near the tank edge, forming a ring for connection of the tank shell. Connections having only circumferential welds have been fatigue tested in two recent studies [7,8]; however, connections with both radial and circumferential welds have not been tested.…”

Section: Introductionmentioning

confidence: 99%

“…The performance of tank connections containing radial welds relative to the existing EC8-4 limit is unknown. This paper expands upon the experimental work in [7,8] by: 1) examining the effects of radial base-plate welds on connection capacity, 2) expanding current experimental data taken from existing tank connections, and 3) creating additional fatigue-life curves for fatigue evaluation of tank connections having radial welds.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effect of radial base-plate welds on ULCF capacity of unanchored tank connections

Prinz

Nussbaumer

2014

Journal of Constructional Steel Research

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The base of large steel liquid storage tanks can uplift during severe earthquakes, causing large inelastic rotations at the connection between the tank shell and tank base. While recent experimental studies indicate significantly higher connection rotation capacity than what is specified in the current Eurocode standard (set at 0.2 rad), additional radial base-plate welds (present in some tank connection details due to fabrication methods) have never been considered in tests. This study experimentally investigates the effects of these radial base-plate welds on the fatigue capacity of tank shell-to-base connections during uplift. Twelve tank shell-to-base connection specimens taken from existing tanks throughout Switzerland are tested at rotation ranges greater than the current Eurocode limit (eight specimens with radial welds and four specimens without radial welds). Testing indicates that tank base-plate sections containing radial welds govern the shell-to-base rotation capacity during uplift. The rotation capacity of connections containing radial welds was nearly 30% lower (on average) than equivalent connections without radial welds. This reduced capacity is directly related to the reduced base-plate ductility created by the radial weld heat affected zone. All connection capacities were far greater than the current Eurocode limit.

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Section: Test Overviewsupporting

confidence: 61%

Section: Test Overviewmentioning

confidence: 99%

Section: Test Overviewmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of radial base-plate welds on ULCF capacity of unanchored tank connections

Prinz

Nussbaumer

2014

Journal of Constructional Steel Research

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Seismic risk assessment of liquid storage tanks via a nonlinear surrogate model

Bakalis

Vamvatsikos

Fragiadakis

2017

Earthq Engng Struct Dyn

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Summary A performance‐based earthquake engineering approach is developed for the seismic risk assessment of fixed‐roof atmospheric steel liquid storage tanks. The proposed method is based on a surrogate single‐mass model that consists of elastic beam‐column elements and nonlinear springs. Appropriate component and system‐level damage states are defined, following the identification of commonly observed modes of failure that may occur during an earthquake. Incremental dynamic analysis and simplified cloud are offered as potential approaches to derive the distribution of response parameters given the seismic intensity. A parametric investigation that engages the aforementioned analysis methods is conducted on 3 tanks of varying geometry, considering both anchored and unanchored support conditions. Special attention is paid to the elephant's foot buckling formation, by offering extensive information on its capacity and demand representation within the seismic risk assessment process. Seismic fragility curves are initially extracted for the component‐level damage states, to compare the effect of each analysis approach on the estimated performance. The subsequent generation of system‐level fragility curves reveals the issue of nonsequential damage states, whereby significant damage may abruptly appear without precursory lighter damage states.

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On the low-cycle fatigue capacity of unanchored steel liquid storage tank shell-to-base connections

Prinz

Nussbaumer

2012

Bull Earthquake Eng

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Under strong earthquake motions, the liquid stored within large unanchored steel tanks can cause rocking and uplift of the tank base from the supporting foundation. Repeated rocking can lead to low-cycle fatigue fractures in the tank base-plate, and ultimately spillage of tank contents. Due to limited research on tank connection capacity, current European and New Zealand tank standards (EuroCode8 part 4 and NZSEE) impose unjustified rotation limits on tank shell-to-base connections (current limit being 0.2 rad). These rotation limits often govern the design of new tanks, and many existing tanks require retrofit to meet compliance. This paper experimentally investigates the fatigue capacity of tank shell-to-base connections, with a focus on the effects from material ductility and applied strain range (rotation range). Twenty-seven tank connections representing two steel material grades are fatigue tested under constant range rotation cycles to generate fatigue-life curves. Tensile loads applied to the base-plate simulate membrane action present in tanks during uplift. Results indicate that the strain capacity of the base-plate base material strongly influences connection fatigue capacity as fatigue fractures originate in the base material away from the weld toe and weld heat affected zone. Increasing base-plate ductility drastically increases connection fatigue life. All connection specimens sustained multiple uplift cycles at rotations greater than the existing EuroCode8 and NZSEE limits.

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Experimental determination of the rotational capacity of wall-to-base connections in storage tanks

Cited by 17 publications

References 8 publications

Effect of radial base-plate welds on ULCF capacity of unanchored tank connections

Effect of radial base-plate welds on ULCF capacity of unanchored tank connections

Seismic risk assessment of liquid storage tanks via a nonlinear surrogate model

On the low-cycle fatigue capacity of unanchored steel liquid storage tank shell-to-base connections

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