Parametrically excited oscillation of stay cable and its control in cable-stayed bridges＂

This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.

Comparative Study on Structural Redundancy of Cable-Stayed and Extradosed Bridges Through Safety Assessment of Their Stay Cables

This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.

Study on longitudinal wind load calculation method of cables for cable-stayed bridge

Along with the expanding of span of cable-stayed bridge,wind load becomes a more and more important controlling factor for bridge the design.A very large proportion of the wind load acting on cables has exceeded that acting on deck.There was not any detailed prescript in Chinese code for calculation of longitudinal wind load on cables due to lack of theoretical research and experiment,and conservative simplified calculation was adopted during design,which leads to conservative and uneconomical design of structures.To resolve this problem,cable force experiment was carried out during the design of Sutong Bridge.By comparing with international research results,the calculation formula of longitudinal wind drag coefficient for cables was advanced to fill the blank of bridge wind resistant code of China,and has already been adopted in the Highway Bridge Wind Resistant Design Code(JTG/T D60-01-2004)with great significance for bridge engineering.

Dynamic Characteristics Evaluation of Innovative UHPC Pedestrian Cable Stayed Bridge

KICT (Korea Institute of Construction Technology) is conducting a project called “SUPER BRIDGE 200—Development of Low Cost and Long Life Hybrid Cable Stayed Bridge”. This project aims to reduce the construction and main- tenance costs of long-span bridges by 20% and double their lifetime through the exploitation of ultra-high performance concrete (UHPC). This paper presents the design and construction of the first pedestrian cable stayed bridge using UHPC developed by KICT. UHPC, compared to conventional concrete, has not only high compressive and tensile strengths but also high ductility. The UHPC developed at KICT is a steel fiber-reinforced cement compound presenting design compressive strength larger than 180 MPa and design tensile strength exceeding 10 MPa with water-to-binder ratio below 0.24 and admixing of 2 volume percentage of steel fiber. To show the applicability of UHPC to structures, a pedestrian cable stayed bridge (Super Bridge I) exploiting the characteristics of the developed UHPC has been planned, designed and erected at KICT. The dimension of UHPC deck is 2.7 m × 7 m as a precast segment with a typical thickness of deck of only 7 cm. However, harmful crack was observed in the deck at the time of the fabrication of the deck segments. Accordingly, new fabrication method was conceived and applied to prevent cracking of the UHPC slender deck. Four UHPC deck segments were fabricated successfully without any crack. After construction, the dynamic characteristics (natural frequencies and mode shapes) were evaluated through vibration tests since several users felt excess vibration. A vertical tuned mass damper (TMD) was proposed and installed on the parapet of the bridge. The TMD reduces the acceleration by about 30% from 0.0316 g to 0.0244 g when two pedestrians are crossing the bridge.

NONLINEAR TRANSIENT RESPONSE OF STAY CABLE WITH VISCOELASTICITY DAMPER IN CABLE-STAYED BRIDGE

Taking the bending stiffness, static sag, and geometric non-linearity into consideration, the space nonlinear vibration partial differential equations were derived. The partical differential equations were discretized in space by finite center difference approximation, then the nonlinear ordinal differential equations were obtained. A hybrid method involving the combination of the Newmark method and the pseudo-force strategy was proposed to analyze the nonlinear transient response of the inclined cable-dampers system subjected to arbitrary dynamic loading. As an example, two typical stay cables were calculated by the present method. The results reveal both the validity and the deficiency of the viscoelasticity damper for vibration control of stay cables. The efficiency and accuracy of the proposed method is also verified by comparing the results with those obtained by using Runge-Kutta direct integration technique. A new time history analysis method is provided for the research on the stay cable vibration control.

A simplified fragility analysis of fan type cable stayed bridges

A simplified fragility analysis of fan type cable stayed bridges usingProbabilistic Risk Analysis (PRA) procedure is presented for determining their failure probabilityunder random ground motion. Seismic input to the bridge support is considered to be a riskconsistent response spectrum which is obtained from a separate analysis. For the response analysis,the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses ofthe springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysisprovides a coupled stiffness matrix for the spring system. A continuum method of analysis usingdynamic stiffness is Used to determine the dynamic properties of the bridges .The response of thebridge deck is obtained by the response spectrum method of analysis as applied to multi-degree offreedom system which duly takes into account the quasi - static component of bridge deck vibration.The fragility analysis includes uncertainties arising due to the variation in ground motion,material property, modeling, method of analysis, ductility factor and damage concentration effect.Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM)method of reliability. A three span double plane symmetrical fan type cable stayed bridge of totalspan 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure areobtained under a number of parametric variations. Some of the important conclusions of the studyindicate that (ⅰ) not only vertical component but also the horizontal component of ground motionhas considerable effect on the probability of failure; (ⅱ) ground motion with no time lag betweensupport excitations provides a smaller probability of failure as compared to ground motion with verylarge time lag between support excitation; and (ⅲ) probability of failure may considerablyincrease for soft soil condition.

Genetic Algorithms-based Optimization of Cable Stayed Bridges

Optimum design of cable stayed bridges depends on number of parameters. Design of Cable stayed bridge satisfying all practical constraints is challenging to the designers. Considering the huge number of design variables and practical constraints, Genetic Algorithms (GA) is most suitable for optimizing the cable stayed bridge. In the present work the optimum design is carried out by taking total material cost of bridge as objective function. During problem formulation most of the practical design variables and constraints are considered. Using genetic algorithms some parametric studies such as effect of geometric nonlinearity, effect of grouping of cables, effect of practical site constraints on tower height and side span, effect of bridge material, effect of cable layout, effect of extra-dosed bridges on optimum relative cost have been presented. Data base is prepared for new designers to estimate the relative cost of bridge.

Rolling Fatigue Test of Large-Sized UHPC Member for Cable Stayed Bridge

Recently, research strives to apply Ultra High Performance Concrete (UHPC) to large-sized structures owing to its remarkable mechanical performance and durability compared to normal concrete. The Korea Institute of Construction Technology proposed SuperBridge800, an edge girder type UHPC cable stayed bridge with central span of 800 m, through its detailed design. The bridge is designed to be erected through the connection of precast UHPC segments. The precast UHPC segment is monolithically composed of one ribbed deck slab and edge girders at each side. The connection between the precast segments is achieved by steel bars at the edge girders and by UHPC cast-in-place wet joint at the slab. Despite of the outstanding mechanical performance of UHPC, the fabrication of large-sized members is a difficult task since UHPC hardens faster than normal concrete and requires a special curing process. Therefore, the constructability of large-sized UHPC segment should be secured to achieve SuperBridge800. Besides, the performance of the connection between segments should also be guaranteed, especially in terms of the fatigue performance of the UHPC cast-in-place joint, which constitutes a weak point. To that goal, two half-scaled UHPC segments are manufactured and the constructability is examined by fabricating a large-sized UHPC member connected with respect to the design conditions. This study conducts rolling fatigue test on the so-fabricated large-sized UHPC member. Rolling fatigue test is carried out up to 2 million cycles considering actual vehicle load at each center and quarter points of the member. The test results confirm that the service limit state is satisfied.

Study on Fatigue Behavior of Anchorage of Cable and Girder of Long Span Cable-Stayed Bridge

A full scale model test is done and a FEM model is established to investigate the fatigue behavior of the Nancha cable stayed bridge of the Nanjing Second Yangtz River Bridge, a long span steel bridge with a main span of 628 m. The results of test and FEM are analyzed and compared. It is shown that they are in good agreement. It is verified that the fatigue characteristic of the anchorage structure of cable and girder of the bridge satisfies the requirements specified by Chinese, British and American codes.

Closure technique for the hybrid girder cable stayed bridge of Edong Bridge

Based on Edong Yangtze River Bridge, which is the second longest hybrid girder cable stayed bridge with 926 m long main span, the influencing factors and crucial techniques of the main span closure method for long span hybrid girder cable stayed bridge are studied. After theoretical analysis, numerical evaluation and practical test, the loading assistant closure method is employed in Edong Yangtze River Bridge. The loading assistant closure method, with better thermal adaptability and less influence on bridge line and the forced status, can meet the requirements of the unstressed state control method. Based on the mentioned advantages, the loading assistant closure method is applicable to long span hybrid girder cable stayed bridges. The conclusion can provide a reference for the further design of the similar brid^es.

Impact of pre- and peri-operative risk factors on length of stay and hospital readmission following minimally-invasive partial nephrectomy

Objective:We conducted an analysis of the American College of Surgeons National Surgical Quality Improvement Program database for minimally-invasive partial nephrectomy cases reported with the goal to identify pre-and peri-operative variables associated with length of stay(LOS)greater than 3 days and readmission within 30 days.Methods:Records from 2008 to 2018 for“laparoscopy,surgical;partial nephrectomy”for prolonged LOS and readmission cohorts were compiled.Univariate analysis with Chi-square,t-tests,and multivariable logistic regression analysis with odds ratios(ORs),p-values,and 95%confidence intervals assessed statistical associations.Results:Totally,20306 records for LOS greater than 3 days and 15854 for readmission within 30 days were available.Univariate and multivariable analysis exhibited similar results.For LOS greater than 3 days,undergoing non-elective surgery(OR=5.247),transfusion of greater than four units within 72 h prior to surgery(OR=5.072),pre-operative renal failure or dialysis(OR=2.941),and poor pre-operative functional status(OR=2.540)exhibited the strongest statistically significant associations.For hospital readmission within 30 days,loss in body weight greater than 10%in 6 months prior to surgery(OR=2.227)and bleeding disorders(OR=2.081)exhibited strongest statistically significant associations.Conclusion:Multiple pre-and peri-operative risk factors are independently associated with prolonged LOS and hospital readmission within 30 days of surgery using the American College of Surgeons National Surgical Quality Improvement Program data.Recognizing the risks factors that can potentially be improved prior to minimally-invasive partial nephrectomy is crucial to informing patient selection,optimization strategies,and patient education.

Reducing Extended Hospital Lengths of Stay

In the United States, the costs of health care have become a major burden for the health care system. In order to address this problem, the hospitals of Syracuse, New York, developed programs to provide subacute and complex care. The Subacute programs provided patient transportation services for dialysis and other types of care outside hospitals. They also developed programs for services such as intravenous therapy in nursing homes. The Complex Care Programs, such as intravenous therapy and mental health services, have provided alternatives to extended care in hospitals. During the past five years, utilization of these programs has varied, declining between 2019 and 2022, and then increasing between 2022 and 2024. The programs have avoided the need for 1530 - 2974 patient days in hospitals. The programs saved the Syracuse hospitals approximately $600 per inpatient day. This amounted to savings of $918,000 - $1,784,400 per year. These programs demonstrated how relatively small mechanisms can save large amounts of health care resources.

旅游小城镇规划中的Long Stay要素分析

根据小城镇具有发展Long Stay的条件,在进行小城镇规划建设中考虑Long Stay要素的体现,并对旅游小城镇的效益进行了分析。结果表明:小城镇具有发展Long Stay的条件,在城镇的总体规划中体现出其作用,并能对城镇产生经济效益与社会效益。

“Long Stay”与分时度假的比较分析

"Long Stay"与分时度假是休闲旅游的两种特殊形式,"Long Stay"刚进入国人视野,前景看好,而分时度假在国内的发展陷入困境。通过对比两者的主体、客体以及在我国发展的适应性,发现两者具备一定的互补优势,协同发展可以实现产品价值最大化和企业利润最大化。

Effects of Water Stress on Stay Green of Sugarcane Innovative Materials Yunge F_2 Generation

[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female parent, were selected as the experimental materials. Based on the observation on appearance of stray green and other five physiological and biochemical indexes, the drought resis- tance of the experimental materials was evaluated comprehensively by subordinate function method, grey relational analysis, and cluster analysis. [Result] The rank of drought resistance of the experimental materials was not exactly the same between subordinate function method and grey relational analysis. However, the drought .re- sistance evaluation results by isometric range-based cluster analysis were consistent with those by the two foregoing methods except Yunge F2 11-68 and Yunge F1 11- 254. At the Euclidean distance of 2.00, the tested materials were classified into four groups. The first group included 8 drought-strongly resistant materials, the third group included 6 drought-moderately resistant materials, the fourth group included 3 drought-poorly resistant materials, and the second group included drought-strongly resistant and drought-moderately resistant materials. The drought resistance coeffi- cients of green leaf numberLtotal leaf number and top four leaves chlorophyll content showed significantly positive correlation with drought resistance comprehensive eval- uation value, thus green leaf number/total leaf number and top four leaves chloro- phyll content could be used as the evaluation indexes of drought resistance in sug- arcane. [Conclusion] The excellent materials possess strong drought resistance and good green holding performance, such as Yunge F2 11-159, can be used as crucial parents and basic germplasm materials in drought resistance breeding of sugarcane. 7

Analysis of the Long Stay Elements in the Planning of Small Tourism Towns

According to the conditions to develop Long Stay in small tourism towns,the demonstration of Long Stay in the planning and construction of small towns was taken into consideration,and its benefits for tourism towns were analyzed.The results showed that small tourism towns were endowed with sound conditions to develop Long Stay,which played its role in the overall planning of towns and would benefit the economic development of these towns.

“play+stay”理念在营口理工学院网球课中的应用研究

2007年2月ITF正式发起了一项意在增加全球网球参与性的运动——play+stay。它的目标是使网球这项运动更容易、更有趣和更健康。并保证每一位初学者在第一堂课中都能够掌握发球、对打和得分的能力。"play+stay"的理念主要包括5部分:网球是简单的;网球是有趣的;网球比赛是有趣的;网球是健康的;网球适合所有人。营口理工学院于2012年开始设置了网球课程,并与2014—2015学年引入了"play+stay"理念并结合自身的特点和教学经验进行了教学实验,得出以下结论:(1)"play+stay"理念非常适合高校网球教学。(2)同学们的学习热情显著提高,网球技能水平达到了教学目标的要求。(3)"play+stay"理念应与高校自身的特点相结合才能发挥最大的优势。

Study on the Development of "Farm Stay" Tourism in Yanan City of Shaanxi Province

'Farm stay' tourism is a kind of new tourism form in recent years,which can promote regional economic development.The study discusses the existing problems in the setting of tourism products,and puts forward some countermeasures for the development of 'farm stay' tourism in Yanan city.

Evaluation of the inclusive payment system based on the diagnosis procedure combination with respect to cataract operations in Japan------A comparison of lengths of hospital stay and medical payments among hospitals

Following the recommendations of a report submitted by the Central Social Insurance Medical Council concerning the 2002 revision of the Medical Service Fee Schedule, a new inclu-sive payment system, which is based on the Diagnosis Procedure Combination (DPC) sys-tem, was introduced in 82 special functioning hospitals in Japan, effective beginning in April 2003. Since April 2004, the system has been gradually extended to general hospitals that satisfy certain prerequisites. In this paper, the new inclusive payment system is analyzed. Data pertaining to 1,225 patients, who were hospital-ized for cataract diseases and underwent lens operations from July 2004 to September 2005, are used. The lengths of hospital stay and medical payments among hospitals are com-pared. Even after eliminating the influence of patient characteristics, there are large differ-ences among hospitals in average lengths of hospital stay and DPC-based inclusive pay-ments. The highest average inclusive payment is 3.5 times as high as the lowest payment. On the other hand, there are relatively small differ-ences in non-inclusive payments based on the conventional fee-for-service system—the larg-est deviation from the average of all hospitals is approximately 10%. Thus, although payments based on the DPC account for only one-third of the total medical payments for this disease, the major differences in medical payments among hospitals are caused by differences in their DPC-based inclusive payments. The results of the study strongly suggest that revisions of the payment system in Japan are necessary for the efficient use of medical resources in the future.

Clinical Predictors of Prolonged Hospital Stay after Acute Stroke: Relevance of Medical Complications

Purpose: This study aims to identify clinical predictors of prolonged hospital stay after acute stroke based on data collected from a prospective hospital-based acute stroke registry. Methods: All patients with first-ever ischemic stroke and primary intracerebral hemorrhage included in the Sagrat Cor Hospital of Barcelona stroke database over a 17-year period were assessed. Prolonged hospital stay was defined as hospitalization for longer than 12 days after admission. Demographic data, cardiovascular risk factors, clinical factors, neuroimaging findings, and outcome were compared in patients hospitalized for more or less than 12 days. Logistic regression analysis was used to assess the independent influence of statistically significant variables in the bivariate analysis and duration of hospitalization. Results: Of a total of 3112 acute stroke patients included in the study, prolonged hospital stay was recorded in 1536 (49.4%). Male sex (OR = 1.16), limb weakness (OR = 1.79), vascular complications (OR = 2.68), urinary complications (OR = 2.56), and infectious complications (OR = 1.78) were independently associated with longer stay, whereas symptom free at discharge (OR = 0.45) and lacunar infarction (OR = 0.43) were inversely associated with prolonged hospitalization. Conclusion: In-hospital medical complications (vascular, urinary, and infectious) are relevant factors influencing duration of hospitalization after acute stroke. Therefore, prevention of potentially modifiable risk factors for medical complications is an important aspect of the early management of patients with stroke.