Residual Deformation Effects Research Articles

A climatology of thermodynamic vs. dynamic Arctic wintertime sea ice thickness effects during the CryoSat-2 era

Abstract. Thermodynamic and dynamic sea ice thickness processes are affected by differing mechanisms in a changing climate. Independent observational datasets of each are essential for model validation and accurate projections of future sea ice conditions. Here, we present a monthly, Arctic-basin-wide, and 25 km resolution Eulerian estimation of thermodynamic and dynamic effects on wintertime sea ice thickness from 2010–2021. Estimates of thermodynamic growth rate are determined by coupling passive microwave-retrieved snow–ice interface temperatures to a simple sea ice thermodynamic model, total growth is calculated from a weekly Alfred Wegener Institute (AWI) European Space Agency (ESA) CryoSat-2 and Soil Moisture and Ocean Salinity (SMOS) combination product (CS2SMOS), and dynamic effects are calculated as their difference. The dynamic effects are further separated into advection and residual effects using a sea ice motion dataset. Our results show new detail in these fields and, when summed to a basin-wide or regional scale, are in line with previous studies. Across the Arctic, dynamic effects are negative and about one-fourth the magnitude of thermodynamic growth. Thermodynamic growth varies from less than 0.1 m per month in the central Arctic to greater than 0.3 m per month in the seasonal ice zones. High positive dynamic effects of greater than 0.1 m per month, twice that of thermodynamic growth or more in some areas, are found north of the Canadian Arctic Archipelago, where the Transpolar Drift and Beaufort Gyre deposit ice. Strong negative dynamic effects of less than −0.2 m per month are found where the Transpolar Drift originates, nearly equal to and opposite the thermodynamic effects in these regions. Monthly results compare well with a recent study of the dynamic and thermodynamic effects on sea ice thickness along the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) drift track during the winter of 2019–2020. Couplets of deformation and advection effects with opposite signs are common across the Arctic, with positive advection effects and negative deformation effects found in the Beaufort Sea and negative advection effects and positive deformation effects found in most other regions. The seasonal cycle shows residual deformation effects and overall dynamic effects increasing as the winter season progresses.

Seismic evaluation of friction spring‐based self‐centering braced frames based on life‐cycle cost

AbstractIn recent decades, a variety of self‐centering braces (SCBs) have been developed to address the limitations of conventional frames by decreasing residual drift due to earthquakes. However, the initial construction cost of self‐centering (SC) structures is expected to be higher and the study about its cost‐effectiveness over the life‐cycle span is limited. This paper presents a seismic life‐cycle cost evaluation of emerging friction spring‐based self‐centering braced frames (SCB‐Fs) compared with traditional buckling restrained braced frames (BRB‐Fs) when an existing structure is upgraded. Particular focus is on the effect of residual deformation, initial construction cost, and high fatigue performance of the SCB. Following the performance‐based design of the SCB‐F and BRB‐F, system‐level analyses are conducted. Numerical results of case‐study buildings indicate that the total expected annual loss (EAL) of the BRB‐F increases by approximately three times when the effect of residual deformation is considered, while its effect on the total EAL of the SCB‐F is negligible. Besides, the superior performance of the SCB‐F compared to BRB‐F is highlighted by a substantial reduction in EAL induced by earthquakes. In addition, the acceleration‐related seismic losses of SCB‐F constitute approximately 44% of the total EAL. Its contribution is significantly larger in the case of the SCB‐F compared to the BRB‐F. From the perspective of economic benefit, increasing the structural life‐cycle span is beneficial to the SCB‐F compared to the BRB‐F. The high fatigue performance of the SCB is favorable to increase the economic benefit of the SCB‐F, especially when the reduction of repair time is considered. The economic benefit of the SCB‐F compared to the BRB‐F is highly related to the initial construction cost. Taking the 100 years as an expected life‐cycle span, the high initial construction cost of the SCB‐F would not be paid off when the unit cost of the SCB is about 2.1 times that of the BRB.

Effect of Residual Deformation of a Steel Column on its Fire Resistance under Combined Exposure "Explosion-Fire"

Calculations on the example of a steel column showed that with the combined effect of an explosion that causes deformation and subsequent fire, even without damaging the fire-retardant coat, there is a significant decrease in the fire resistance of the structure due to a decrease in the critical temperature. It is shown that, on the basis of the methodology proposed in this work, for hazardous operations industrial facilities, it is possible to predict the stability of steel columns in crash explosions followed by fire, as well as to recommend the values ​​of workloads and parameters of fire-retardant coats providing the necessary stability. It is also shown that when calculating the fire resistance limit of a steel structure with intumescent fire-retardant coat, it is necessary to take into account the proper heating time of steel structures until they lose strength.

Progressive collapse analysis of composite steel frames subject to fire following earthquake

This paper presents three-dimensional progressive collapse analyses of composite steel frames exposed to fire following earthquake. The scenarios of heating columns located in various different fire compartments (internal, edge and corner bay) are first studied to investigate load redistribution paths and members’ interactions within the composite frame. The results show that the loads previously supported by the heated columns are redistributed to adjacent columns along two horizontal directions, a phenomenon which cannot be captured in a 2D model. Then, the 3D model is adopted to investigate the effect of residual deformation after an earthquake on the progressive collapse behaviour of the composite building. It is found that neither the load redistribution path nor the fire resistance of the building is considerably affected by the residual deformation. A series of progressive collapse analyses subjected to travelling fires resulting from fire compartment damage is also performed. It is concluded that the survival of the building can be greatly affected by the spatial nature of the travelling fire as well as the inter-zone time delay.

Effect of Residual Deformation and Reinforcement on Double Column Bridge in Mined-out Area

Effect of Residual Deformation and Reinforcement on Double Column Bridge in Mined-out Area

Peridynamic simulations of brittle structures with thermal residual deformation: strengthening and structural reactivity of glasses under impacts

In glass research, the effect and influence of pre-deformation by thermal or chemical treatment is of great importance when configuring different mechanical properties or scratch resistance on the surface of glasses. In particular, such pre-deformation affects dynamic fracture or damage evolution when glass structures are under impact or collision conditions. Peridynamics provides a seamless approach for the simulation of dynamic damage evolution of the system under aggressive environments. Revising the pair interaction of each material point, the effect of pre-deformation is implemented, and the corresponding damage evolution can be simulated conveniently. Our approach is composed of two steps: first, a static solution is found via energy minimization with thermal boundary conditions in the peridynamic platform. Second, comparing the initial and the pre-deformed structures from the energy minimization, the effect of residual deformation, strengthening and reactive behaviour of brittle structures are seamlessly simulated. The developed methods are applied to the Prince Rupert’s drop and Bologna vial, which are classic examples of strengthened glasses. This study reports the first complete and successful simulation of dynamic behaviour of strengthened glasses, and a significant contribution in simulating residual stress behaviour in any material.

Distribution of Residual Deformation Effects in Shell Tubes from Ferritic-Martensitic Steels

The X-ray method of Generalized Pole Figures was used by study of residual deformation effects in steel shell tubes for high-temperature atomic reactor. Ferritic-martensitic steel contained disperse strengthening oxide particles and their behavior under technological treatment was of essential practical interest. The used procedure estimates residual deformation effects in grains with different orientations and depicts distributions of elastic lattice distortion and interplanar spacings. Invisible oxide particles redistribute within the tube wall and strain hardening at its outer side is higher.

Seismic retrofit design method for RC buildings using buckling-restrained braces and steel frames

Existing RC buildings conforming to relatively older regulations and codes may lack in seismic resistance. This is especially true for public buildings such as schools or hospitals, which demand efficient retrofitting to ensure safety during and after a seismic event. Although retrofit design with conventional braces (CB) has been practiced for decades, the unbalanced hysteresis behavior of CBs tends to result in damage concentrated in specific stories. Buckling-restrained braces (BRBs), a new generation of bracing system, may increase structural integrity and at the same time reduce seismic response in a building via energy absorption. However, when the maximum story drift exceeds the yield point of RC frame, all structural elements including BRBs lose horizontal stiffness, which may result in both damage at a specific story and residual deformation effects occurring after an earthquake. Therefore, BRBs may be applied to such buildings using elastically designed steel frames (SF).This paper discusses the evaluation of damage distribution and self-centering functions of the elastic steel frames that connect BRBs to RC frames. In addition, we propose a simplified method based on equivalent linearization to design the required amount of BRB and elastic SF capacity for retrofitting existing RC buildings. The results were confirmed by nonlinear time-history analysis using high-intensity seismic waves. The results show that RC buildings retrofit with BRBs respond as predicted by the proposed method and target story drift is obtained. The story drifts of the BRB retrofit model is significantly reduced relative to both the original building and the building retrofit with CBs. In addition, because BRBs are attached to an existing building by elastically designed steel frames, the significant effect of SF on the reduction of residual displacements was also shown and discussed.

Recrystallization of BCC Metals: Distribution of Strain Hardening and Texture Formation

Data are presented on the x-ray line broadening distribution over the texture of cold-rolled Nb and Mo sheets. The method of generalized X-ray pole figures, which combine texture measurements with X-ray line profile analysis, is employed. The X-ray line broadening is considered as an indicator of residual deformation effects. It was revealed that these effects in cold-rolled BCC metals rise as the grain orientation shifts away from texture maxima towards texture minima. The intensity of X-ray reflections change during annealing at 200 – 500C and this change correlates with the line broadening. The recrystallization texture of BCC metals is dominated by orientations deflected from the peak maxima by 25 – 30 deg. These orientations in the deformed structure have relatively high stored energy. Their volume fraction is sufficient for them to be able to consume most of the deformed matrix.

Texture versus Residual Deformation Effects in Metal Materials: Principles of Experimental Approach and General Regularities

For systematic study of the distribution of residual deformation effects in textured metal materials the method of Generalized Pole Figures was developed, combining texture measurement with X-ray line profile measurements in such a manner that the profile of the same X-ray line (hkl) is registered by each successive position of the sample. The obtained totality of profiles after that or another treatment is used for construction of Generalized Pole Figures (GPF), i.e. distributions of measured diffraction parameters or calculated substructure parameters in the stereographic projection of the sample depending on the orientation of reflecting crystallographic planes. As applied to metal materials with developed rolling textures it was found that any volume ~1 mm3 is characterized by an extremely wide spectrum of substructure conditions. Three laws of substructure anisotropy were revealed for the first time. The 1st law: Residual deformation effects are minimal along directions, corresponding to maximal density of crystallographic axes, i.e. texture maxima, and increase up to highest values by passing to texture minima. The 2nd law concerns variation of lattice parameters in metal products due to elastic microstrain: For each grain with crystalline lattice, extended along axis <hkl> by (+ε), there is its pair with the symmetric orientation, where along axis <hkl> crystalline lattice is compressed by (-ε), so that accompanying elastic microstresses are equilibrated. The 3rd law: By passing from residual tension of the crystalline lattice to its compression, grain fragmentation changes depending on indexes of the reference axis, i.e. tensile and compressive elastic deformations of the crystalline lattice differ in their uniformity.

Development of Nonuniform Substructure and Microstrain Distribution by Texture Formation in Metal Materials

The substructure nonuniformity of metal materials with developed deformation texture was studied by use of the X-ray method of Generalized Pole Figures. Main regularities of substructure nonuniformity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct cross-wise system, consisting in alternation of quadrants with predominant microstrains of opposite signs.

Regular Substructure Inhomogeneity of Textured Materials by the Example of Rolled Ti-Ni Single Crystals

The substructure inhomogeneity of rolled Ti-48%Ni-2%Fe single crystals was studied by the X-ray method of Generalized Pole Figures. Under rolling of single crystals, along with texture formation, the nonuniform substructure develops. It is conditioned by inhomogeneous reorientation of the crystalline lattice and local differences in predominant plastic deformation mechanisms. The distribution of residual deformation effects is controlled by the orientation of separate regions relative to texture maxima. Rolled single crystals prove to be divided into subcomponents with close orientations and opposite signs of elastic microstrains.

New Principles of the Substructure Development in Metal Materials under Plastic Deformation, Revealed by Advanced X-Ray Methods

The substructure inhomogeneity of real textured metal materials was studied by use of the X-ray method of Generalized Pole Figures and the computer data treatment. Main regularities of substructure inhomogeneity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct system.

Inhomogeneous Distribution of Residual Deformation Effects inTextured Bcc Metals

The distribution of residual deformation effects in textured metal sheets was studied by X‐ray diffractometric methods using a position‐sensitive detector (PSD). The elaborated procedure is based on the geometric principles of texture measurement, while the PSD technique allows to observe the profile of the X‐ray line simultaneously with registering of its intensity. The proper treatment of experimental results gives values of line intensity, half‐width and peak position of each angular position of the studied sample. By analogy with the texture pole figures (TPF), the half‐width pole figures (WPF) and the peak position pole figures (PPF) were constructed. The obtained WPFs describe the distribution of deformation effects in the textured sample depending on grain orientation. The distinct correlation between TPF and WPF is demonstrated for rolled Nb and β‐Zr: maxima of WPF fall to minima of TPF, while minima of WPF are located at maxima of TPF. The PPF exhibits a cross‐wise distribution of elastic strains, providing the mutual equilibrium of extended and contracted regions. To explain this regularity, texture formation mechanisms and probable mutual misorientation of neighbouring grains were considered.