When bridges are subjected to large inelastic deformations during near field ground motions, they do not often return to their initial vertical positions and may have considerable residual displacement. Even if collapse is not occurred, large residual displacements may make them unusable or irreparable. This large residual displacement causes no collapse in bridges while it may make them unusable or irreparable after earthquake. Therefore, the measurement and estimation of residual displacement are of a great deal of importance in assessment and serviceability of bridges after earthquake. The Initial hysteresis models have been developed for dynamic analysis of conventional concrete columns and are often unable to estimate high residual displacements occurred in biased and one-sided motions. The aim of this research is development a new hysteresis model based on peak displacement oriented which is able to provide adequate residual displacement compared to conventional models. This multi linear peak oriented model considers strength deterioration in half cycles in addition to stiffness degradations in unloading cycles. Yielding points differ in both positive and negative sides of hysteresis model enabling us to define a different elastic stiffness of both sides in asymmetric concrete sections.Another remarkable property of this model is breaking points and strength deterioration in unloading and reloading stages, respectively. The performance of conventional hysteresis model was investigated in estimation of seismic residual displacement in cyclic and dynamic analysis in addition to a new combinational hysteresis model. The obtained results indicate that the new studied hysteretic model has higher accuracy in comparison with other current models.

Introduction: Proper stress distribution in the edentulous ridge is necessary for implant-supported mandibular overdenture. For the purposes of the present study, the stress distribution was investigated under various types of forces using the finite element method (FEM). Materials and Methods: A digital model of the mandible with two implants (ITI with diameter and length of 4. 1 and 12 mm, respectively) in canine areas and the overdenture supported by it were simulated using ABAQUS software. A vertical force was applied to the left first molar and gradually increased from 0 to 50 N. Finally, the resultant stress distribution was evaluated. Results: Under small amounts of occlusal force, mucosa displacement and stress accumulation in the cortical bone of edentulous ridge, occurred on the non-working side and moved to the working side with a gradual increase in the force. Major stress accumulation was observed in the cortical bone around the implant. Moreover, it was observed in a minor range in the posterior ridge. The mucosa displacement occurred primarily in the posterior edentulous ridge, especially in the mylohyoid ridge. Conclusions: By using 3D FEM in the present study, it was observed that mucosa displacement is more likely to occur in the posterior areas, especially mylohyoid ridge and edentulous ridge crest in comparison to the areas around the implants. Therefore, this area should be carefully relief and the forces should be directed towards the buccal shelf area as much as possible.

The force-based formulation is attractive because it can model the spread of plasticity along the length of column using only one element and a number of integration points; however, their sensitivity to modeling parameters and models of material behavior has resulted in the estimation of residual displacement seismic demand to be important in this modeling method. In this research, the effects of two theories of lumped plasticity and distributed plasticity on modeling the concrete bridge column for estimating the residual displacement in near field zones were investigated. For estimation of residual displacement, the effects of reinforcing slide, geometrical parameters, and material behavior parameters were studied. Due to the importance of residual displacement in the performance evaluation of damaged structures, estimation of residual displacement is very crucial. In this study, the effects of different modeling methods as well as material behavior parameters on estimation of residual displacement were investigated. For this purpose, five different models were studied and the sensitivity of optimum model to various parameters was evaluated. The results showed that the theory of distributed plasticity for bridge concrete column has a good accuracy for estimating the residual displacement. Reloading strain parameters of concrete behavior and forced-based beam-column fiber element modeling parameters have an important role in estimation of residual displacement.

In structural analysis, P-Delta effect refers to the changes in internal forces due to P-Delta moment which can be found by multiplying gravity load (P) by the lateral displacement of structure for earthquake lateral load (Delta). The influence of PDelta in elastic response of structures is ignorable, but P-Delta effect should be given more attention when the structure responds in inelastic range. On the other hand, the influence of ground motion duration is magnified when P-Delta effect is considered in the structural analysis. In this paper, to consider the simultaneous effect of ground motion duration and P-Delta effect, an algorithm is implemented in MATLAB which employs OPENSEES for linear and nonlinear dynamic analysis of elasto-plastic systems subjected to long-and short-duration records. The analysis results indicate that the frequency of structural collapse for longduration ground motions is about twice of short-duration ground motions. The frequency of collapse also increases when ductility and stability index increase, but decreases when the period of structure increases. Furthermore, the increase of ground motion duration has no influence on the residual displacement of structures, but nonlinear behavior of structures and gravity load effect increase the residual displacements.

The evaluation of residual displacement of structures is a critical problem because it has important role in the Definition of post-earthquake performance level of structures. In this paper, the mean residual displacement ratios (RDRs) (residual displacement normalized by maximum inelastic displacement) are computed for constant ductility of single-degree-of-freedom (SDOF) systems subjected to 116 strong ground motion records from severe earthquakes events in Iran. A total number of 25, 056 nonlinear response history analyses (RHAs) were performed to accurately evaluate RDRs. The influence of frequency content and significant duration of ground motions on mean RDRs are evaluated and discussed statistically. The results indicated that the validity of influence of these ground motion parameters on mean RDRs is dependently of the post yield stiffness ratio and the influence of these parameters becomes more obvious for SDOF systems with post-yield stiffness greater than zero. The obtaining data from RHAs results were used for the development of new mean RDRs equation. It has been found that the proposed equation can predict mean RDRs with adequate accuracy.

The objective of this study is to evaluate the effects of earthquake damage on future seismic performance of reinforced concrete columns. Strength and stiffness modification factors are proposed to modify force-deformation behaviors of damaged columns. Permanent displacement is considered to determine the damage severity. A method is developed to calculate the collapse fragility function of damaged RC columns using permanent displacement. Comparing the fragility function of intact and damaged columns the strength modification factor is calculated for different amount of residual displacement. The stiffness modification factor is also estimated using the change of the fundamental period of a RC column after exciting by ground motions. Having the modified the force-deformation behaviors of damaged columns, the performance of the damaged structure can be evaluated using pushover analysis.

The demand for using industrial waste has increased significantly due to their environmental impacts and limitation of natural resources. Copper waste (CW) is among those that are known to cause environmental problems. Categorized under waste materials, it causes various environmental problems, especially those related to waste disposal. The main purpose of the present study is to investigate the application of CW, as compared to mineral aggregate (MA), in surface treatment. For this purpose, various tests, including wet cohesion test, wet track abrasion test, loaded wheel – displacement test, and loaded wheel – sand adhesion test, were performed on five different mixtures designated as CW0+MA100, CW10+MA90, CW20+MA80, CW30+MA70, and CW40+MA60, with the designations defined based on total aggregate weight. Results showed that, thanks to its unique physical and chemical characteristics, the replaced CW could improve the treatment performance, especially in the CW30+MA70 sample, in terms of abrasion, wet cohesion, and vertical and lateral displacements by about 23, 22, 39, and 33%, respectively, at a residual asphalt of 8%. Also, regarding the analysis of variance, the copper slag is a more effective factor with respect to residual bitumen in increasing the cohesion and reducing the vertical and lateral deformations due to traffic loading

Background: In Genu-valgum tibiofemoral angle increases above its normal value of 6°. This disorder causes difficulty in walking and sport activities in short-.term. But in long-term, because of increased force on lateral compartment of the knee, osteoarthritic changes of the lateral side of the knee and ligamentous laxity of medial side of knee could happen. In the past, osteotomies have been done on lateral side of distal femur for correction of Genuvalgum. We are suggesting a medial approach, posterior to vastus medialis with close-wedge osteotomy from medial side as an alternative approach for correction of genovalgum. Method: A Clinical trial study of 20 lower limbs operated between 1988 to 2002. Results: 20 lower limbs were operated with this technique. The mean age was 23.2, 14 patients were female and 2 male. 10 limbs were left and the other 10 were right side. Mean valgus angle was 14.75° preoperatively and 3° postoperatively the mean follow-up period was 628 days (Minimum 50 and maximum 1111 days). At follow-up, the range of knee motion in all limbs was normal. There was no infection postoperatively, quadriceps force was 5/5 in 18 and 4/5 in two limbs. Functional improvement was observed in 15 cases and all 16 patients had full satisfaction from the appearance of the limbs.

In this paper the effect of corrugations on mechanical sensitivity of diaphragm for MEMS capacitive microphone is investigated. Analytical analyses have been carried out to derive mathematic expression for mechanical sensitivity and displacement of corrugated diaphragm with residual stress. It is shown that the mechanical sensitivity and displacement of diaphragm can be modeled using thin plate theory.The mechanical stress of corrugated diaphragm is calculated using mathematical model and its relationship with residual stress is expressed. The analytical results show that the mechanical sensitivity of diaphragm can be increased using corrugations, because of reducing the effect of residual stress in corrugated diaphragm.