Sharif Digital Repository

This research is aiming to investigate the mechanical behaviour of the temporomandibular joint (TMJ), in response to kinematics/cyclical loading caused through actions of speech and mastication. A set of in-vitro experimental tests has been performed in three different groups on a fresh sheep jaw bone to examine the hypothesis of the study. No failure was monitored during the cyclical test. The study was concluded that the amount of loading is effective on the displacement of the TMJ  

This study proposes a novel type of metallic yielding damper called block slit damper or BSD. This damper is a slit damper with very low height to thickness ratio. This device has high shear capacities, and is more economical than SSD devices with high height to thickness ratios. Based on theoretical analysis the formulation for the BSD device's main parameters is derived. Then to investigate the hysteretic behavior of the proposed devices, 5 specimens with different aspect ratios (height-width ratios) were manufactured and tested in a quasi-static manner. The tests revealed that by reducing the aspect ratios, the shear and energy dissipation capacity increases while the displacement... 

Electrical post insulators are important components of electrical substations since any type of failure in such insulators leads to the breakdown of the local network. Although the electrical substations are often in service condition, any horizontal excitation due to the earthquake, or any extreme event, may cause lateral deformation and damage to the post insulators. Hollow composite post insulators, a new and evolving technology, have a very complex mechanical behavior due to their materials and connections. To date, the design of such post insulators has been based on the limited test results available in the literature. Most of experiments have been conducted on small-scale specimens... 

Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that... 

In this study, a novel type of passive energy dissipation device called a Telescopic Lead Yielding Damper (TLYD) is proposed and analyzed. This device comprises co-axial steel cylinders and lead rings, such that these rings act as shear locks between the steel cylinders. TLYDs dissipate energy through the plastic shear deformation of lead metal. The telescopic mechanism used in TLYDs allows these small-sized dampers to tolerate large axial displacements with low fatigue. For each telescopic level, a yield plateau is added to the hysteresis behavior of TLYD devices. Each yield plateau resists a different performance level, namely design-based and maximum credible earthquakes. Seven... 

Current design codes provide empirical equations for the drift capacity of unreinforced masonry (URM) walls that are based on results of quasi-static cyclic shear-compression tests. Yet different experimental campaigns have used various approaches of imposing fixed-fixed boundary conditions at the wall top which may affect the test results. This article investigates, by means of numerical simulations, the influence of experimental setups on the force and drift capacities of in-plane loaded URM walls subjected to double-fixed conditions. It is shown that controlling the shear span or the top rotation while keeping the axial force constant leads to very similar results. Controlling the axial... 

Stone masonry construction is still a common practice in remote mountainous areas of many developing countries. Field investigations have shown that the traditional construction practices do not usually provide adequate seismic resistance for such buildings. This study was carried out to investigate and improve the construction of single-story stone masonry buildings in terms of safety in extreme events, economy, and ease of construction. The current construction methods were first studied through field investigations, and their deficiencies were identified. Then, improved stone masonry walls were designed that provide some confinement for the masonry by adding steel and reinforced-concrete... 

Strength parameters of asphalt concrete used in earth fill dams' core were studied by conducting cyclic and monotonic triaxial tests on asphalt concrete samples. Results obtained from more than 120 cyclic tests showed that asphalt concrete behaves properly under cyclic loading and specimens stay intact after applying 5000 cycles. Results of monotonic and post-cyclic loading proved that strength parameters of asphalt concrete samples does not change significantly after being subjected to seismic loads. © 2009 IOS Press  

Soils have an anisotropic response, and changing the inclination (α) and magnitude of the major principal stress will affect collapse potential and brittleness, as well as shear strength and shear stiffness. In this paper, the effect of the stress path, with changes in intermediate principal stress, on the dynamic behavior of Babolsar sand, is studied. A series of undrained monotonic and cyclic tests on loose sand with induced anisotropy were conducted by using automatic hollow cylinder apparatus. Special attention was paid to the significant role of the intermediate principal stress parameter (b) in the deformation behavior of the sand during cyclic loading. Results show that at constant α,... 

In this paper, Plate Frame Interaction (PFI) developed by other researches for modeling Steel Plate Shear Wall (SPSW) is applied for designing a half-scale, single bay and one story SPSW. After designing of SPSW, one specimen is constructed accordingly. In order to determine the mechanical properties of steel, coupon test is performed; and then again theoretical relations based on PFI is re-checked. In this study, gravity loads are neglected and only seismic resistance of SPSW is considered. With cyclic lateral loading as quasi-static load, according to Acceptance Criteria for Cyclic Racking Shear Tests For Metal-Sheathed Shear Walls with Steel Framing (AC154) and obtaining its hysteretic... 

Buckling-restrained braces (BRBs) have been spread widely, especially in high seismic hazard zones due to their excellent energy absorption capacity. BRBs are composed of a main load-carrying steel core restrained with other elements mostly made of concrete and steel casing to preserve it from buckling. Although BRBs provide excellent cyclic behavior, a problem is with their heaviness, which leads to difficulties such as installation and transportation. This study presents a numerical and experimental investigation on a BRB with a new proposed restraining system composed of concrete panels confined with partially carbon fiber reinforced polymer (CFRP) strips to reduce the weight of the...