OpenSees is a well-recognized open source platform with high compatibility,and it has a well-developed fiber element method to cope with nonlinear structural analysis.Fiber reinforced polymer(FRP)confined concrete can effectively improve the seismic performance of concrete structures.However,sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees.In this paper,after reviewing several typical FRP confined concrete constitutive models,a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng(2003)’s model with four main modifications including the determination of FRP rupture strain,ultimate condition,envelope shape,and hysteretic rules.To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation.Hence,the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart.Finally,with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases,FRP confinement types and geometric properties,the utility and accuracy of the proposed model compared with Lam and Teng(2003)’s model and new material secondary development in OpenSees were well validated.
A simple but applicable analytical model is presented to predict the lateral distribution of the depth-averaged velocity in meandering compound channels. The governing equation with curvilinear coordinates is derived from the momentum equation and the flow continuity equation under the condition of quasi-uniform flow. A series of experiments are conducted in a large-scale meandering compound channel. Based on the experimental data, a magnitude analysis is carried out for the governing equation,and two lower-order shear stress terms are ignored. Four groups of experimental data from different sources are used to verify the predictive capability of this model, and good predictions are obtained. Finally, the determination of the velocity parameter and the limitation of this model are discussed.
In this work,we report a new two-dimensional Sr（II） coordination polymer,namely,[Sr（L）（phen）（H2O）]（1）,based on 3,5-dinitro-salicylic acid（H2L） and 1,10-phenanthroline（phen）.It crystallizes in monoclinic,space group P21/c with a = 15.479（3）,b = 9.4020（19）,c = 13.884（3） A,β= 103.76（3）°,V= 1962.5（7） A3,Z = 4,C19H12SrN4O8,Mr = 511.95,Dc = 1.733 g/cm3,F（000） =1024,μ（MoKα） = 2.805 mm-1,R = 0.0411 and wR = 0.1069.In 1,each L anion bridges three Sr（Ⅱ）atoms by using carboxylate and hydroxyl groups,yielding a two-dimensional layer structure.The phen ligands are alternately attached to both sides of the layer.The n-n stacking between L and phen in the same layer and hydrogen-bonding interactions between water molecule and carboxylate oxygen atom play an important role in stabilizing the layer structure of 1.The solid state luminescent property of 1 was also studied at room temperature.
Quadtree-based Cartesian grid was automatically generated from specified geometry.Adaptive refinements were performed according to geometric parameters and solution of flow field.An altered CCST(curvature corrected symmetry technique)approach was proposed to apply solid wall boundary conditions. Driven flows in a square cavity and flows around NACA0012airfoil were simulated and compared with the result of published structured grid and stretched Cartesian grid.The results show that solid wall boundary condition are accurately applied by current altered CCST approach,while incompressible/compressible subsonic, transonic and supersonic viscous flows are adequately simulated with adaptively refined Cartesian grid.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)