S. Jayakumar, Dr R. Saravanane,
Volume 8, Issue 4 (12-2010)
Abstract
Puducherry is a coastal region in India where the growth of Ulva fasciata (Delile) is very abundant on all marine structures. Though the detrimental effect of this macro algae Ulva fasciata is a secondary one, its effect has to ascertain. To know its effect, the basic mechanism by which Ulva fasciata deteriorates concrete structures, M20 grade concrete cubes were casted and kept in the coastal area where there is abundant growth of Ulva fasciata and also laboratory simulation has been carried out. To ascertain the detrimental effect by the macro algae on concrete surface, samples were collected from the concrete cubes kept in the coastal area and also from the laboratory simulated one. The collected samples were analyzed by SEM, EDX and XRD to establish the degree of deterioration done by marine algae on concrete surface. The SEM and EDX results showed that there is a remarkable change in the base materials viz., Ca and Si content and XRD results revealed the absence of Calcium Hydroxide. Both the results confirmed the biodeterioration of concrete by the marine green algae.
H. Liu, M. He, J. Guo, Zh. Hou, Y. Shi,
Volume 13, Issue 2 (6-2015)
Abstract
Self-centering pier (SCP) has been viewed as a remarkable accomplishment which is able to sustain major lateral loading with reduced structure damage in seismic engineering. Stiffness deterioration observed in experiment is vital for the seismic performance of self-centering concrete pier. In this contribution, the associated stiffness deterioration with respect to the structural damage is modeled in a modified analytical model for SCP comprehensively. In the proposed modified theoretical model, the lateral force-displacement relation associated with the stiffness reducing is analyzed. Three damage factors are introduced in the stiffness deterioration analysis to illustrate the damage evolution caused by gradually increasing lateral displacement. The proposed modified quasic-static model with damage evolution or stiffness deterioration has been validated against an experiment we conducted, where a good agreement is clearly evident. Subsequently, a parametric investigation focusing on aspect ratio, initial pre-tension, and ratio of ED (Energy Dissipator) was conducted to evaluate the hysteretic behavior of SCP under quasi-statically cyclic loading.
Abdolreza S.moghadam, Masoud Nekooei, Ramin K.badri,
Volume 14, Issue 8 (12-2016)
Abstract
This paper investigates the effect of different deteriorating hysteretic model parameters on the response of asymmetric buildings. The example buildings are 5-story symmetric and asymmetric buildings. The maximum interstory drift ratio over the height of building is selected as the structural response in this study. A proper hysteretic model is used to simulate the deterioration properties of structural elements. The median response of building with different mass eccentricities is evaluated by 3D modeling. The results are provided for both torsionally stiff and torsionally flexible buildings. The results show that the effect of deterioration parameters are different for flexible side and stiff side elements. Those effects are mainly significant for higher intensity levels. That intensity threshold level is independent of all hysteretic parameters except for the plastic rotation capacity.
