Utilizing Superelastic Shape Memory Alloy Strand

Utilizing Superelastic manakin Memory Alloy StrandI tried to maintain the composition in following order cosmopolitan background on sword MFRs before Northridge quakeWhat happened after(prenominal) Northridge quake and still what are the puzzles remaining?What are the approaches taken to solve the problem?Concept of Post tensioned familiarityStudies on PT friendship with marqueAlternative to leaf blade establish (previous studies on SMA strand).Objective of this psychoanalyse.Feasibility ponder of utilizing superelastic shape entrepot dilute strand in domiciliate tensioned make charge column connections for mitigated seismic performanceIntroductionDuring the 1960s, welded brand name peter-column connections were considered to be the most ductile carcass against seism. Therefore, a number of industrial and commercial buildings were constructed in the western part of united democracys at that time. However, the Northridge earthquake of January 14, 1994, indicate d that welded connections are susceptible to brittle fracture at the beam-to-column joints. This failure modal value was observed even for complex body parts subjected to a moderate level of ground shaking. Although, these buildings didnt bump (which is desired by the building code), the connection way was not as expected. Further investigation revealed that similar damage was observed in a limited number of buildings during 1992 Landers, 1992 Big Bear and 1989 Loma Prieta earthquake (FEMA-350). Studies have been carried step to the fore to investigate the reasons behind it. Based on the investigation, signifi trampt aspiration changes was employ to the pre-Northridge flash resisting frame designs (Engelhardt and Sabol, 1997).Post-Northridge structures are designed in such(prenominal) a way that it is still expected to sustain damage during puckish earthquake solely without affecting the life safety limit (Chancellor et al. 2014). Residual crookedness that may exist after the earthquake bear require expensive repair works and in some cases the demolition of natural structures. Depending on the scenario, the total cost of demolition or repair work can be a burden to the overall economy of a country. An pillowcase can be the earthquake of magnitude 6.5 that occurred in Christchurch, New Zealand in May 2014. The repair works required 40$ billion (New Zealands dollar) which was somewhat 20% of the total GDP of the country. In another study, McCormick et al. (2008) showed that the repair of structures with symmetricalness drift greater than 0.005 rad is not economically feasible.Conventional moment resisting frames are designed to resist collapse by using the inelastic properties of nonreplaceable elements. Therefore, these systems can dissipate energy during bear-sized inelastic contortion but unable to recover the relaxation deformation. In this regard, research has been done to improve the performance by introducing reduced beam section (RBS) ( Tremblay and Filiatrault, 1997), connection reinforced with cover plates (Engelhardt and Sabol, 1997), haunches (Uang et al. 2000), and side plates (Shiravand and Deylami, 2010). However, the existence of residual deformation after horrendous earthquake is still possible.To address this above mentioned issues, a new phase of lateral force resisting system has been developed which can sustain severe earthquake with little or no residual deformation. This smart structure can return to its plumb position after load removal (herein referred to as a full self-centering), without any residual deformation. This new system is termed as moorage tensioned (PT) brand moment resisting frames. In this system, beams are post tensioned to the columns, which run parallel to the beams and pass through the column flanges, are utilise to provide self-centering to the moment resisting frames (Moradi and Alam, 2015). The decrement of residual displacement in PT connection is controlled by a shif t opening mechanism. Due to the gap opening between stain column and beams, a significant reduction in stiffness occurs, which is desirable. As the decrease in stiffness attracts slight force to the connection (i.e. softening occurs without morphologic damage) by aloofnessening the structural period (Chancellor et al. 2014).Past few years, several researchers have investigated and still investigation the seismic performance of self-centering steel moment resisting frames. Ricles et al. (2002), experimentally investigated the self-centering behavior of steel PT connection on five cruciform shaped specimens. The results showed that steel PT connection sustain small residual deformation compared to the naturalized welded connection. Further study based on several affecting parameters such as flange reinforcing plate, shim plate, number of PT strand, angle size, and gage aloofness are considered by Garlock et al. 2003, 2005. The effect of floor diaphragm on the self-centering beha vior of steel moment resisting frames were investigated by Garlock et al. (2007). A performance based design guideline for self-centering PT connection was also outlined. In design procedure, the fundamental interaction between the floor system and the self-centering PT connection was considered. Dobossy et al. (2006) proposed a mode for assessing structural limit state probabilities for a self-centering frame (with top-and-seat angles). Monte Carlo affectation was delectationd for generating demand curves. The possibility of exceeding a limit state at each floor of the structure was determined based on the demand and capacity curves. Herning et al. (2011) used a reliability based mode to evaluate the likelihood of arrive at the limit state of PT strand yielding. A predictive relationship between the beam-column relative rotation and the story drift was proposed. Based on the results, the response of three nonlinear models of archetype self-centering frames was found to be ade quate to thousands of synthetic ground motions. The probability of reaching the limit state of strand yielding ranged from 0 to 15%.The self-centering might of PT connection can also be improved by using smart materials such as shape depot demoralizes (SMAs). cast Memory Alloy (SMA) is a class of equiatomic metal showing mechanised properties not present in materials usually employed in engine room application (Fugazza, 2003). In most cases NiTi is referred to as a shape memory alloy. But some other alloys show the same characteristics of NiTi alloy. If not verbalise otherwise, NiTi go forth be used as SMA throughout this paper. The importance of Shape Memory Alloy (SMA) in civil engineering application is change magnitude rapidly due to its strength of large strain recovery, absence of residual strain upon unloading and high energy dissipation ability. This exceptional airplane propeller can be used in post tensioned steel beam column connection. The idea of implementing shape memory alloy on post tensioned connection has already been investigated by a number of previous studies. Ocel et al. 2004 considered ii partially restrained (PR) connection to investigate their performance during static and cyclic loading. Martensitic phase (Shape memory effect) was used in both connection. The tested connection was capable of dissipating large energy without any strength degradation up to a drift level of 4%. Using SMA tendons, about 54% and 76% of the beam tip displacement was recovered with or without phony dead loads, respectively. Ma et al. (2007) presented a highly ductile steel beam column connection by using shape memory alloy bolt. The bolts shanks are 1.2 times longer than the conventional steel bolt. These bolts provide the ductility to the connection by absorbing inelastic deformation. After the deformation phase, it can regain its original shape by recovering 94% of the total deformation. Desroches et al. (2010) studied the behavior of shape m emory alloy (SMA) on both austenite and martensite phase. The superelastic SMA bars were found to be responsible for reducing the residual deformation and martensitic bars were efficient in controlling peak deformations. Ellingwood et al. (2010) evaluated the performance of steel frames with or without SMA connections based on probabilistic framework. Four interior steel beam column connection incorporating different types of SMA (i.e. martensitic NiTi and austenite NiTi) and steel tendon, were investigated by Speicher et al. (2011). The connection incorporating superelastic NiTi alloy was able to recover up to 85% of its deformation after being loaded upto 5% drift.The objective of this study can be categorized in two phase. In phase one, an attempt has been do to reduce the strand length of existing PT connection without affecting the performance of the connection. In parallel to this study, the objective of phase two was to use shape memory alloy with reduced length. A recent st udy done by Chowdhury et al. (2017) show that the reduction of PT strand length directly affect the stiffness, strength and moment capacity. Besides, PT connection loses self-centering capability due to the yielding of steel strand. This is due to the high stress compactness in steel and its low strain capacity. In this regard, shape memory alloy can be an efficient alternative due to its large strain capability (recoverable strain up to 8% for NiTi). The cost of NiTi alloy is a major concern during its application. Therefore, reduced strand length will reduce the cost without affecting performance.