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Lifetime assessment of structural concrete: Multi-scale and multi-chemo-mechanistic approach
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
The impact of shrinkage and associated time dependent mechanics have been experienced not only in structural members such as decay of shear capacity of RC beams, but also the entire structural rigidity. For instance, the structural dynamics and the maximum drift of buildings may be affected by the stiffness change of constituent members owing to shrinkage and associated time-dependent mechanics. The numerical simulation and experimental results on seismic performance of building with different curing states are illustrated in Figure 11 (Kurihara et al. 2017). As slabs and walls are of smaller thickness, quick moisture loss under dried curing may induce the shrinkage stresses and cracking close to the junction planes between members. Thus, the initial global rigidity of the entire building is reduced, and the dynamic drift of each floor is enlarged under dynamic loads. While the seismic responses could be reduced under the perfect sealed curing.
Polysaccharide-Based Polymers in Cosmetics
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
Kappa- and iota-carrageenans are structurally similar in that the (1,4)-linked D-galactose (9) is made more rigid by formation of a five-membered cyclic anhydride ether group between the C6R5 and C3R3 carbon atoms. The presence of the 3,6 -anhydride ether causes the chains of these carrageenans to more fully extend in solution by making the monosaccharides more rigid. Lambda-carrageenan, lacking this structural rigidity, assumes a more crimped α-(1,4)-linkage like that already seen in the L-guluronic acid portion of the alginates (Section III.A.1.a). The anhydride also creates a more hydrophobic (water-avoiding) environment in this portion of the monosaccharide. To minimize interaction of the anhydride ether with water, these two polysaccharides form tightly wound double helices when dissolved, the interiors of which house the anhydride ether functionality. The lambda-carrageenan does not form double-helical coils and, as discussed below, cannot form aqueous solution gels.
Probabilistic structural identification and condition assessment of prestressed concrete bridges based on Bayesian inference using deflection measurements
Published in Structure and Infrastructure Engineering, 2023
Siyi Jia, Mitsuyoshi Akiyama, Bing Han, Dan M. Frangopol
The deterioration of aging concrete structures is spatially distributed. The stochastic field representation of the distribution of structural rigidity is advantageous over the point-in-space probabilistic model in that it facilitates the localization and quantification of damage (Papakonstantinou & Shinozuka, 2013). In this paper, a one-dimensional stochastic field of structural rigidity is defined over the longitudinal direction of the bridge, which refers to the spatial distribution of the reduction factor of the local stiffness matrix λD. The global stiffness matrix ke is then represented as a summation of the local stiffness matrix ke,u for the uth section along the longitudinal direction of the bridge, weighted by the structural rigidity ratio λD,u that remains invariant for all elements within the section:
Scattering of linear gravity-capillary waves by a completely submerged vertical porous elastic plate
Published in Waves in Random and Complex Media, 2022
The variation of reflection coefficient is depicted against Kb for various values of the porous-effect parameter with fixed values of in Figure 5. A flexible porous plate with is chosen in Figure 5(a) whereas a rigid porous plate with is chosen in Figure 5(b). A similar pattern of the curves is observed for all the different values of . As the plate becomes more porous with the increasing absolute value of , the reflection coefficient tends to decrease. This trend is very much obvious because a porous plate would let the waves pass through it than reflecting them back. Here also similar to Figure 4, very small values of can be seen from the graph, which is due to the collective impact of the structural porosity, structural rigidity, and surface tension. Another important point to note here is that a rigid porous plate gives almost double the peak values of obtained in the case of a flexible porous plate. Thus highly flexible porous plates can serve the purpose whenever a minimal amount of wave reflection is required.
Static and thermal instability analysis of embedded functionally graded carbon nanotube-reinforced composite plates based on HSDT via GDQM and validated modeling by neural network
Published in Mechanics Based Design of Structures and Machines, 2022
Ali Forooghi, Nasim Fallahi, Akbar Alibeigloo, Hosein Forooghi, Saber Rezaey
Figure 6 depicts the dimensionless natural vibrational frequency against the variations of the CNT volume fraction for various BCs of the system. As it is visible, the stiffer edge BCs, the more the bending rigidity of the plate. In other words, it is striking that greater constraints of boundaries translate to greater values for dimensionless fundamental frequencies. As apperceived, when one edge of the system varies from simply supported to clamped, the non-dimensional frequency of the studied system increase. This trend is due to the enlargement in the local flexural rigidity of the considered plate with stiffening of the edge support. As a result, the clamped BCs predict higher vibrational frequencies for the studied system than other types. Meanwhile, the stiffness-hardening effect induced by adding reinforcement elements to the FG-CNTRC plate on the structural rigidity is well apperceived in this figure. Also, by comparing the presented results in this work and published ones by Adhikari and Singh (2019), a suitable consistency can be perceived.