VOL. 5, NO. 11, NOVEMBER 2010 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2010 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com STRENGTHENING OF JIAMUSI PRE-STRESSED CONCRETE HIGHWAY BRIDGE BY USING EXTERNAL POST-TENSIONING TECHNOLOGY IN CHINA Ali Fadhil Naser and Wang Zonglin School of Transportation Science and Engineering, Bridge and Tunnel Engineering, Harbin Institute of Technology, China E-Mail: ali_hu73@yahoo.com ABSTRACT External post-tensioning is defined as a system in which the pre-stressing tendons or bars are located outside the concrete section. The pre-stressing force is transferred to the member section through the end anchorages, deviators or saddles. The objectives of this study are to strengthen Jiamusi pre-stressed concrete highway bridge by using external post- tensioning tendons, to determine the internal forces, and to design the external post-tensioning system. Two software are used in the analysis of the T-shaped cantilever structure and anchor beam. The first is Dr. Bridge software Ver. 3.1, and the second is Ansys software Ver. 10. The results of analysis before and after laying the leveling layer of the bridge deck pavement show that the section of T-shaped cantilever structure can satisfy the demand of vehicle-20 grade and vehicle-50 grade. The compressive stress of the upper edge of pier top box section is small, it is only 1.91Mpa. Therefore, there is need to strengthen the top of the bridge deck. External post-tensioning tendons are used to strengthen the bridge deck. The selection of external post-tensioning tendons depends on the ASTMA416-90A specification. The external tendons consist of high strength, low relaxation strands, and the standard tensile strength is 1860MPa. The design and construction of external post-tensioning system includes the design and construction of anchor beam which includes the design of re-bars and the design of damper devices, and the layout of external post-tensioning tendons along the bridge deck. Keywords: concrete bridges, strengthening, external tendons, shear stress, analysis, design, Jiamusi, China. INTRODUCTION The strengthening of concrete structure involves upgrading of the strength and stiffness of a structure members. The strengthening of the bridge structural members can be attempted by replacing poor quality or defective materials by better quality materials, attaching additional load-bearing materials, and re-distribution of the loading actions through imposed deformation on the structure system. The selection of an appropriate method for the strengthening and repair of the bridge structural members depends on a number of factors. The factors include the type and age of structure, the importance of structure, the magnitude of the strength required which that is need to increase, the type and degree of damage, available materials, cost and feasibility, and aesthetics [1, 2]. The pre-stressing systems can be defined as the preloading of a structure before the application of the service loads, and consist of two types of pre-stressing. The first type is known as pre-tensioning pres-stressing and the second type is known post-tensioning pre- stressing. Post-tensioning is a method of strengthening of concrete structure with high strength steel strand or bars referred to as tendons [3]. External post-tensioning is defined as a system in which the pre-stressing tendons or bars are located outside the concrete section. The pre-stressing force is transferred to the member section through end anchorages, deviators or saddles. The use of external post-tensioning became popular in the last two decades, after the improvement for corrosion protection of external tendons by methods such as epoxy and grease coating [4, 5, 6]. External post-tensioning system consists of high strength tendons, ducts, and grout pipes. Tendons are combined from steel bars or strand. Anchorage is the point where the pre-stressing force is applied and consists of anchor head or wedge plate, wedge, bearing plate, duct transition, and grout tube connections. Duct is a sheath for pos-tensioning tendons, grout pipes are attached to the duct to place concrete for internal tendons [7]. The main aim of the bridge structure strengthening by using additional external pre-stressing tendons is to fulfill all necessary serviceability criteria and not to extend its ultimate limit state. The use of external post-tensioning for the strengthening of existing bridges has been used in many countries since the 1950s and has been found to provide an efficient and economic solution for a wide range of bridge types and conditions. [8, 9]. Strengthening by using external post-tensioning is simply the application of an axial load combined with bending moment to improve the flexural and shear capacity of the bridge structural members [10]. The objectives of this study are to explain the strengthening of Jiamusi pre-stressed concrete highway bridge by using external post-tensioning tendons, to determine internal forces, and to design the external post- tensioning system. In this study, two software are used in the analysis of T-shaped structure and anchor beam. The first is Dr. Bridge software Ver. 3.1 and the second is Ansys Ver. 10. DESCRIPTION OF THE BRIDGE STRUCTURE Jiamusi pre-stressed concrete highway bridge is located across the Songhua river in the Jiamusi city within Heilongjiang province in the east north of China. The total 60