Development of a divergent fluid wall damper for framed structures subjected to dynamic loads

This study developed a new adaptive design for a divergent fluid wall damper (DFWD). This design decreases the dynamic vibration in reinforced concrete (RC) structures subjected to dynamic forces caused by earthquakes, wind, tsunamis, and explosions. The DFWD comprises a tank connected to the lower floor that is filled with a fluid and a plate with fins located inside the tank connected to the upper floor. The DFWD uses a bypass system mechanism that circulates fluid inside the wall damper tank through a divergent pipe and controls the fluid pressure during vibration using a double‐acting valve. To evaluate the performance of the DFWD in RC‐frame structures, we fabricated and experimentally evaluated a prototype of the device based on a new adjustable design. Two RC frames, a bare frame and a frame with DFWD, were cast with the same geometric specifications. These frames were then examined in terms of the time history of applied displacement with a maximum amplitude of 40 mm under the same conditions. The valves in the design of the DFWD were adjustable, and the fully open valve condition was examined. The results indicated that the failure capacity of the frame was significantly improved compared to that of the bare frame as the DFWD absorbed more dynamic force. The ductility of the RC‐frame structure equipped with the DFWD was improved by almost 17.8% compared to that of the bare frame

Development of divergent fluid wall damper for steel-framed structures subjected to dynamic load

This article presents the development of new adjustable and adaptive designs of divergent fluid wall dampers (DFWDs) that can diminish the effect of earthquakes on framed structures. The concept and mechanism of DFWDs is based on the bypass system, which is made by controlling the fluid flow inside the wall damper container using bypass pipes and by controlling the fluid pressure through a double-acting valve. The prototype of the DFWD device is fabricated based on a developed design, and the performance of the DFWD installed in steel frames is evaluated through experimental tests. For this purpose, three steel frames with the same geometric specifications are casted and tested in equal conditions, which include bare frame (BF), braced frame (BrF), and frame equipped with DFWD. All specimens are subjected to dynamic cyclic load and the response of the DFWD is evaluated when the valves are 100% open, 50% open, and 100% closed in comparison with the BF and BrF system to assess the performance of the DFWD in various conditions. The results indicate that the frame furnished with the DFWD in all conditions of fully open, half-open, and fully closed valves were able to absorb and dissipate more force than the BF by almost 28%, 53%, and 73%, respectively

ElectronTransfer Induced Ring Opening of α-Epoxyketones: Spirodioxolane Formation

Stereospecific formation of spirodioxolanes has been observed on electron transfer induced ring opening of α-epoxyketones by 2,4,6-triphenylpyrylium tetrafluoroborate in the presence of cyclohexanon

Isolation, characterization and x-ray structure determination of 2,5-bis(4-methylbenzylthio)-1,3,4-thiadiazole

The reaction of hydrazine hydrate with carbon disulfide and 4-methylbenzyl chloride in basic solution yielded 2,5-bis(4-methylbenzylthio)-1,3,4-thiadiazole (C18H18N2S3, compound 1) in addition to the expected S-4-methylbenzyldithiocarbazate. The molecule has approximate twofold symmetry with the C=S bond lying on the pseudo axis. The five membered ring is planar with the three S atoms mutually syn, and with pendent 4-methylbenzylthio substituents; the dihedral angle between the terminal rings is 52.21(7)°. The compound 1 crystallizes in the triclinic space group $P\bar{1}$ with a = 6.0139(3) Å, b = 11.8694(7) Å, c = 12.6330(7) Å, α = 72.583(5)°, β = 82.827(4)°, γ = 89.882(4)° and Z = 2