兴安县界首镇修桥捐助碑的历史解读及应用价值

碑刻史料是一种厚重的民间文书,同样能够真实地反映历史。广西兴安县界首镇《设立渡桥两岸鼎新行人方便过者欢欣聚善踊跃》捐助碑反映了当地民众捐资修桥的史实,是解读当地社会和经济发展状况的宝贵资料。其与地方社会力量整合、民众对修建渡桥的认可程度以及当地经济发展水平等历史信息密切相关,能帮助人们更深入地了解清代界首地方社会的发展,正史对此并无详细记载,从中亦可挖掘碑刻史料的应用价值。

修桥、祭桥与拆桥——黔东南“敬桥”习俗及相关法律问题

生活在贵州省黔东南苗族侗族自治州的苗、侗、水、布依等少数民族都有"敬桥"的习俗。台江、雷山、三穗、黎平等地一直保留着这一民间传统,各民族对"桥"是十分尊重和敬仰的,大到长度几十米的水泥桥,小到类似桥状的板凳都普遍加以信仰,各地"敬桥"文化有相似之处,又各具特色,反映了各民族群众"求子"、"育子"和修桥积福,祈求家族兴旺的心理。在祭桥过程中与"祭桥权"相关纠纷的出现,成为当地司法实践中一类新的疑难问题。

保补给线路畅通 迎波浪水下修桥

渡河作战历来是一项十分艰巨的任务。到了近代,随着军事科技的发展,装备在复杂化、现代化的同时,也实现了“重型化”,一辆坦克竟然有几十吨重,渡河更成了难上加难的事。于是,渡桥便成为双方斗争的一个焦点,一方要竭力保证桥梁畅通,以利调兵和运送物资,一方则要千方百计地破坏桥梁,以便打乱对方的行动计划。渡河作战上升为军事科学中一个专门的学科,利用谋略保护桥梁也受到人们越来越多的重视。

Finite element model updating and validating of Runyang Suspension Bridge based on SHMS

Based on the finite element （FE） program ANSYS, a three-dimensional model for the Runyang Suspension Bridge （RSB） is established. The structural natural frequency, vibration mode, stress and displacement response under various load cases are given. A new method of FE model updating is presented based on the physical meaning of sensitivity and the penalty function concept. In this method, the structural model is updated by modifying the parameters of design, and validated by structural natural vibration characteristics, stress response as well as displacement response. The design parameters used for updating are bounded according to measured static response and engineering judgment. The FE model of RSB is updated and validated by the measurements coming from the structural health monitoring system （SHMS）, and the FE baseline model reflecting the current state of RSB is achieved. Both the dynamic and static results show that the method is effective in updating the FE model of long span suspension bridges. The results obtained provide an important research basis for damage alarming and health monitoring of the RSB.

架扶贫桥铺致富路

架扶贫桥铺致富路牛湾乡是洛南县一个贫困山区乡，板桥村背靠商州，地处县境边隆僻壤。山区道路与河流多处交叉相汇，来往行人通过需涉水过河，交通十分不便，制约村乡经济的发展。我厅扶贫工作组及时向省厅领导汇报。厅领导当机立断，拿出一万元帮助解决村乡基础建设。如...

Numerical and theoretical verification of modified cam-clay model and discussion on its problems

Isotropic consolidation test and consolidated-undrained triaxial test were first undertaken to obtain the parameters of the modified cam-clay(MCC)model and the behavior of natural clayey soil.Then,for the first time,numerical simulation of the two tests was performed by three-dimensional finite element method(FEM)using ABAQUS program.The consolidated-drained triaxial test was also simulated by FEM and compared with theoretical results of MCC model.Especially,the behaviors of MCC model during unloading and reloading were analyzed in detail by FEM.The analysis and comparison indicate that the MCC model is able to accurately describe many features of the mechanical behavior of the soil in isotropic consolidation test and consolidated-drained triaxial test.And the MCC model can well describe the variation of excess pore water pressure with the development of axial strain in consolidated-undrained triaxial test,but its ability to predict the relationship between axial strain and shear stress is relatively poor.The comparison also shows that FEM solutions of the MCC model are basically identical to the theoretical ones.In addition,Mandel-Cryer effect unable to be discovered by the conventional triaxial test in laboratories was disclosed by FEM.The analysis of unloading-reloading by FEM demonstrates that the MCC model disobeys the law of energy conservation under the cyclic loading condition if the elastic shear modulus is linearly pressure-dependent.

Innovative Applications of Post-Tension for Restoration and Rehabilitation of Bridges and Structures--Case Studies in India

This paper deals with new and innovative case studies of application of post-tensioning for restoration of structures for buildings, bridges and rock stabilization in India. In earlier situations for these types of cases conventional method of repair and rehabilitation has been used. These innovative approaches for restoration have led to enormous saving of cost and time. The advantages of post tensioning are well known in the civil industry and are being used for the last 40 to 50 years. Post tensioning is one of the best methods to induce stresses in the concrete before application of live load and this technique can also be widely used for restoration and rehabilitation of structures. Unlike the use of post-tensioning in new structures there are no definite methods or codes for application in restoration and rehabilitation of structures. For restoration and rehabilitation of structures, PT （post tensioned） technique can be applied in combination with other techniques and materials available. Bridge lifting is a tricky and risky job especially when the superstructure is displaced appreciably by a natural calamity, etc.. Not only the present state of structure needs proper study before commencement of restoration and rehabilitation but also calls for careful execution. This paper deals with case studies of innovative applications of post tensioning in restoration and rehabilitation of structures and restoration of bridge structure in Andaman ＆ Nicobar Island, India affected by Sumatra quake.

Dynamic Detection of Reinforced Concrete Bridge Damage by Finite Element Model Updating

The present work consists of dynamic detection of damages in reinforced concrete bridges by using a MMUM （mathematical model updating method） from incomplete test data. A well suited finite element model of a repaired bridge is carried out. The diagnosis enables us to locate and detect the damage in a reinforced concrete bridge. Thus, developments of analytical predictions have been checked by modal testing techniques. Besides, the FTCS （finite time centered space） scheme is developed to solve the set of equations which can easily handle finite element matrices of a bridge model. It is shown in this study that the method is applied to detect damages as well as existing cracks in real time of a repaired bridge. To check the efficiency of the method, the repaired bridge of OuedOumazer in Algeria has been selected. It is proven that identification methods have been able to detect the exact location of damage areas to be corrected avoiding the inaccuracy from the finite element model for the mass, stiffness and loading.

Modified Cam-Clay model incorporating unified nonlinear strength criterion

A unified nonlinear strength criterion(i.e UNS criterion) is proposed,for the sake of versatility,to capture the complex strength behaviors of frictional materials in geotechnical field.It covers wide ranges on the meridian and octahedral planes to describe nonlinear strength behaviors of soils.The Modified Cam-Clay model,incorporating the unified nonlinear strength criterion,is employed as an example to derive working mathematical equations and to illustrate yielding surfaces in three-dimensional stress space for improving the model's predictive capability.The unified nonlinear strength criterion,demonstrated here,is capable of capturing the experimental results of different types of soils on the meridian and octahedral planes.In addition,the revised model,based on this unified nonlinear strength criterion,though very simple,is versatile to predict the true triaxial test results from literature when considering the influences of the intermediate principal stress on strength and deformation under complex stress conditions.

Damage identification method of girder bridges based on finite element model updating and modal strain energy

A timely and accurate damage identification for bridge structures is essential to prevent sudden failures/collapses and other catastrophic accidents.Based on response surface model(RSM)updating and element modal strain energy(EMSE)damage index,this paper proposes a novel damage identification method for girder bridge structures.The effectiveness of the proposed damage identification method is investigated using experiments on four simply supported steel beams.With Xiabaishi Bridge,a prestressed continuous rigid frame bridge with large span,as the engineering background,the proposed damage identification method is validated by using numerical simulation to generate different bearing damage scenarios.Finally,the efficiency of the method is justified by considering its application to identifying cracking damage for a real continuous beam bridge called Xinyihe Bridge.It is concluded that the EMSE damage index is sensitive to the cracking damage and the bearing damage.The locations and levels of multiple cracking damages and bearing damages can be also identified.The results illuminate a great potential of the proposed method in identifying damages of real bridge structures.

Theoretical model for the improved PCC pile using expansive concrete

Conventional PCC pile technique has been widely used as embankment piles for highway construction in China. To further improve the PCC pile capacity, the expansive concrete technique has been applied to the PCC pile to replace the normal concrete recently. The use of expansive concrete for the PCC pile could increase the pile diameter as well as the contact pressure at the pile-soil interface due to the expansion process of concrete, which allows the improved PCC pile to provide higher capacity than the conventional PCC pile. This paper presents a theoretical model for the new improved PCC pile using expansive concrete technique. The model is formulated by assuming the PCC pile installation process as large strain undrained cylindrical cavity expansion and the subsequent pile shaft expansion combined with soil consolidation process is simulated by the small strain cylindrical cavity expansion combined with strain-controlled consolidation. Then, similarity solution technique is used to solve the problem of cavity expansion in modified cam Clay （MCC） model, while the strain-controlled consolidation is calculated through the finite difference method （FDM）. Subsequently, the suitability of the cavity expansion solution in the interpretation of the PCC pile installation is verified by comparing the calculated excess pore pressure with the measured value in an instrumented field test. The stress changes and excess pore pressure during the PCC pile installation and subsequent pile shaft expansion are investigated by means of parametric study. The proposed theoretical model first reveals and quantifies the fundamental mechanism of the PCC pile using expansive concrete technique and it provides a theoretical basis for developing design methods of the new improved PCC pile in the future.