Experimental Study of Steel Plate Composite Shear Wall Units under Cyclic Load

Zhen Guo,Yingshu Yuan 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.3

A novel type of steel plate composite shear wall that was assembled by using a steel plate and precast cement-based concrete plate is presented in this paper. The steel plate shear wall, which differs from normal steel plate shear walls, was trilaterally constrained with an elastic restraint side. The precast concrete slab was designed to prevent steel plate buckling. Six steel plate shear wall specimens were tested by using a hydraulic servo actuator. The failure mode, shear resistance, lateral stiffness, and buckling mode were investigated through an experimental study. The results indicate that the width-thickness ratio of the steel plate affected the shear-carrying capacity and failure mode. A low width-thickness ratio of steel plate required adequate bonding to prevent boundary failure. The precast concrete slabs enhanced the lateral stiffness and improved the buckling strength or shear resistance of the steel plate. The material workable capability of steel plate was fully developed with a composite buckling-restraint by using the composite shear wall; similarly, the earthquake-resistant behavior of the structural system would likewise be enhanced further.

Fire Resistances of Restrained Steel Beams Subjected to Fire Loads

Zhen Guo,Rui Gao,Xuecheng Zhang,Xingzhi Jia 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

Conventional fire loads and fire resistances of a steel beam still lack an adequate correlation. This paper has established therelationship between the responses of restrained steel beams and fire actions by using a new definition of fire resistances and a newexpression of fire loads. By using reduction factors of elastic modulus and yield strengths, has presented three critical equations topredict the limit state of a restrained steel beam in a fire. Based on these equations and the heat transfer formula, the paper provided anew definition of fire resistances. By using the heat release rate and effective rate coefficient of thermal absorption, a new expressionof fire loads has been argued. Compared with tests, the proposed approach in this paper is in good agreement with the measuredvalues in tests. The results show that the new fire resistances could be able to reflect the facts of heat transfers and duration time. Incontrast to conventional fire loads, the new fire loads are more efficient to indicate a fire load.

Intraoperative inspection alone is a reliable guide to the choice of surgical procedure for enteroenteric fistulas in Crohn’s disease

( Zhen Guo ),( Xingchen Cai ),( Ruiqing Liu ),( Jianfeng Gong ),( Yi Li ),( Lei Cao ),( Weiming Zhu ) 대한장연구학회 2018 Intestinal Research Vol.16 No.2

Background/Aims: Resection of the diseased segment and suture of the victim segment is recommended for enteroenteric fistula in Crohn’s disease (CD). The main difficulty in this procedure remains reliable diagnosis of the victim segment, especially for fistulas found intraoperatively and inaccessible on endoscopic examination. We aimed to explore whether intraoperative inspection alone is reliable. Methods: Patients undergoing conservative surgery between 2011 and 2016 for enteroenteric fistulas complicating CD were identified from a prospectively maintained database. Patients were divided according to whether the victim segment was evaluated by preoperative endoscopy + intraoperative inspection (PI group) or by intraoperative inspection alone (I group). Outcomes were compared. Results: Of 65 patients eligible for the study, 37 were in in the PI group and 28 were in the I group. The baseline characteristics were similar between the groups, except for the rate of emergency surgery (0/37 in PI group vs. 5/28 in I group, P=0.012). Fistulas involved more small intestines (4/37 in PI group vs. 15/28 in I group, P< 0.001) and fewer sigmoid colons (17/37 in PI group vs. 4/28 in I group, P=0.008) in I group due to accessibility with endoscopy. No difference was found in postoperative complications, stoma rates, postoperative recurrence, or disease at the repair site between the 2 groups (P >0.05). Conclusions: For fistulas found intraoperatively and inaccessible on endoscopic examination, intraoperative inspection was a reliable guide when choosing between en bloc resection and a conservative procedure. (Intest Res 2018;16:282-287)

Behaviour of Endplate Joints Subjected to Elevated Temperature after Cyclic Loads

Zhen Guo,Xuecheng Zhang,Xingzhi Jia 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11

This paper presents the performance of an end-plate joint at elevated temperature after cyclic loads. Prime interest of the end-plate joints, subjected to elevated temperature, lies on the effect of three kinds of external conditions: monotonic loads, cyclic loads and local damages. Parametric studies have been systematically conducted using simplified models. The Behaviour of endplate joints subjected to high temperature is examined under two levels of damage caused to the structure, i.e., deformation damage and fracture damage under earthquake. Numerical results indicate that dead loads on beam and material properties of endplate joints are still playing a significant role in fire resistance. Under only deformation damage, the dominance of joints’ resistance to fire is still primarily the property of the material itself. Once experiencing fracture damage, for instance endplates fracture and bolts breakage, the behaviour of joints will degrade severely in post-earthquake fire. The results of this study demonstrate that the deformation damages has limited effect on the endplate joint at elevated temperature after an earthquake. The achieved results can be adopted during the design stage in order to minimize the probability of collapse in the fire.

Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor

Zhenguo Li,Songfa Zhang,Shenghai Zhou,Jin-Woo Ahn 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge 120° conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

Oscillation criteria of second order neutral difference equations

Zhenguo Zhang,Xiaojing Lv,Tian Yu 한국전산응용수학회 2003 Journal of applied mathematics & informatics Vol.13 No.1-2

Comprehensive Method of Enhancing business process efficiency using BPMS

Zhenguo Wang,Hyerim Bae 대한산업공학회 2008 대한산업공학회 춘계학술대회논문집 Vol.2008 No.5

When a company uses the BPM (Business Process Management) system, BP (Business Process) efficiency can be influenced by different task assignments and performance sequence of task performers. Consequently, improvement of BP efficiency depends on two different perspectives: PEP (Process Engine Perspective) and TPP (Task Performer Perspective). PEP focuses on task assignment to proper task performer and TPP decides performance sequence of each task performer to improve BP efficiency. We developed a comprehensive approach that applies the two perspectives and build-time and run-time phases are considered separately. For the build-time phase, a new task assignment policy has been introduced from managerial view point by applying Analytic Process Model (APM), and for the run-time phase, a scheduling algorithm has been applied to improve BP efficiency. Furthermore, for the validation of our approach, we compared with previous research by conducting simulation of sample processes.

Incorporating workload balancing and resource efficiency to enhance business process efficiency

Zhenguo Wang,Hyerim Bae,SungMin Kim 대한산업공학회 2007 대한산업공학회 추계학술대회논문집 Vol.2007 No.11

Existence of positive solutions of second-order nonlinear neutral differential equations \\with positive and negative terms

Zhenguo Zhang,Aijun Yang,Congna Di 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

Mesoscale modelling of concrete for static and dynamic response analysis Part 1: model development and implementation

Zhenguo Tu,Yong Lu 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.2

Concrete is a heterogeneous material exhibiting quasi-brittle behaviour. While homogenization of concrete is commonly accepted in general engineering applications, a detailed description of the material heterogeneity using a mesoscale model becomes desirable and even necessary for problems where drastic spatial and time variation of the stress and strain is involved, for example in the analysis of local damages under impact, shock or blast load. A mesoscale model can also assist in an investigation into the underlying mechanisms affecting the bulk material behaviour under various stress conditions.Extending from existing mesoscale model studies, where use is often made of specialized codes with limited capability in the material description and numerical solutions, this paper presents a mesoscale computational model developed under a general-purpose finite element environment. The aim is to facilitate the utilization of sophisticated material descriptions (e.g., pressure and rate dependency) and advanced numerical solvers to suit a broad range of applications, including high impulsive dynamic analysis. The whole procedure encompasses a module for the generation of concrete mesoscale structure; a process for the generation of the FE mesh, considering two alternative schemes for the interface transition zone (ITZ); and the nonlinear analysis of the mesoscale FE model with an explicit time integration approach. The development of the model and various associated computational considerations are discussed in this paper (Part 1). Further numerical studies using the mesoscale model for both quasistatic and dynamic loadings will be presented in the companion paper (Part 2).