51 research outputs found
Establishment of performance-based seismic design factors for precast concrete floor diaphragms
This paper presents an analytical study used to establish design factors for a new seismic design methodology for precast concrete floor diaphragms. The design factors include diaphragm force amplification factors Κ and diaphragm shear overstrength factors Ωv
Current and Future Drug Targets in Weight Management
Obesity will continue to be one of the leading causes of chronic disease unless the ongoing rise in the prevalence of this condition is reversed. Accumulating morbidity figures and a shortage of effective drugs have generated substantial research activity with several molecular targets being investigated. However, pharmacological modulation of body weight is extremely complex, since it is essentially a battle against one of the strongest human instincts and highly efficient mechanisms of energy uptake and storage. This review provides an overview of the different molecular strategies intended to lower body weight or adipose tissue mass. Weight-loss drugs in development include molecules intended to reduce the absorption of lipids from the GI tract, various ways to limit food intake, and compounds that increase energy expenditure or reduce adipose tissue size. A number of new preparations, including combinations of the existing drugs topiramate plus phentermine, bupropion plus naltrexone, and the selective 5-HT2C agonist lorcaserin have recently been filed for approval. Behind these leading candidates are several other potentially promising compounds and combinations currently undergoing phase II and III testing. Some interesting targets further on the horizon are also discussed
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Experimental study of deformable connection consisting of friction device and rubber bearings to connect floor system to lateral force resisting system
This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and thereby to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a friction device (FD) and carbon fiber-reinforced laminated low-damping rubber bearings (RB), denoted as the FD + RB connection. The test results show that the force-deformation responses of the FD + RB connection are stable under quasi-static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD + RB connection force-deformation response is approximated with a bilinear elastic-plastic force-deformation response with kinematic hardening. The FD is axially stiff, compact, easy-to-assemble, and able to accommodate the FD + RB connection kinematic requirements. The FD elastic stiffness controls the FD + RB connection elastic stiffness. The FD friction force controls the force when the FD + RB connection force-deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post-elastic stiffness to the FD + RB connection. The machining tolerances for the FD components, the âbreak-inâ effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12-story reinforced concrete wall building with FD + RB connections under seismic loading show that a reduction of the FD friction force increases the FD + RB connection deformation demand
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Experimental study of deformable connection consisting of friction device and rubber bearings to connect floor system to lateral force resisting system
This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and thereby to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a friction device (FD) and carbon fiber-reinforced laminated low-damping rubber bearings (RB), denoted as the FD + RB connection. The test results show that the force-deformation responses of the FD + RB connection are stable under quasi-static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD + RB connection force-deformation response is approximated with a bilinear elastic-plastic force-deformation response with kinematic hardening. The FD is axially stiff, compact, easy-to-assemble, and able to accommodate the FD + RB connection kinematic requirements. The FD elastic stiffness controls the FD + RB connection elastic stiffness. The FD friction force controls the force when the FD + RB connection force-deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post-elastic stiffness to the FD + RB connection. The machining tolerances for the FD components, the âbreak-inâ effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12-story reinforced concrete wall building with FD + RB connections under seismic loading show that a reduction of the FD friction force increases the FD + RB connection deformation demand
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Experimental study of deformable connection consisting of buckling-restrained brace and rubber bearings to connect floor system to lateral force resisting system
This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and, thereby, to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a buckling-restrained brace (BRB) and steel-reinforced laminated low-damping rubber bearings (RB). The test results show that the forceâdeformation responses of the connection are stable, and the dynamic force responses are larger than the quasi-static force responses. The BRB+RB forceâdeformation response depends mainly on the BRB response. A detailed discussion of the BRB experimental forceâdeformation response is presented. The experimental results show that the maximum plastic deformation range controls the isotropic hardening of the BRB. The hardened BRB forceâdeformation responses are used to calculate the overstrength adjustment factors. Details and limitations of a validated, accurate model for the connection forceâdeformation response are presented. Numerical simulation results for a 12-story reinforced concrete wall building with deformable connections show the effects of including the RB in the deformable connection and the effect of modeling the BRB isotropic hardening on the building seismic response. Copyright © 2016 John Wiley & Sons, Ltd
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