# Retrofitting of a Multi-Span Simply Supported Bridge into a Semi-Integral Bridge
## 1 Introduction  
Bridges with reinforced concrete structures are subject to deterioration, especially due to corrosion effects, and especially at the expansion joints and bearings. The preservation of these transportation infrastructures is of paramount importance for the daily traffic safety and security of modern communities [1]. The use of integral and semi-integral abutments in bridge engineering has become increasingly popular due to their ability to eliminate expansion joints and bearings, resulting in reduced maintenance and enhanced durability. Integral abutment bridges (IABs), where the superstructure and abutmentsform a monolithic connection, accommodate thermal expansion and seismic forces while offering cost and maintenance benefits.  
The state-of-the-art practice of integral abuthem bridges (IABs) has been explored extensively in the literature for their simplicity and resilience. [PERSON] [2] emphasizes their benefits in seismic regions, tackling soil-structure interaction challenges. [PERSON] [3] compares U.S. and European practices, highlighting design variations. [PERSON] [4] examines evolving Ontario standards. [PERSON] and [PERSON] [5] provide a comprehensive historical analysis, while [PERSON] [6] focuses on monitoring and maintenance strategies. [PERSON] et al. [7] and [PERSON] and [PERSON] [8] delve into early design methodologies, detailing their cost-effectiveness and long-term durability.  
Multi-span, simply supported beam bridges are used widely in China. The superstructures are generally precast box beams or voided slabs. Link slabs are used to make a partially continuous structure and eliminate water leakage to eliminate deck expansion joints over piers, while expansion joints are commonly set between the beams and the abutments. The use of link slabs and deck expansion joints are among the primary factors affecting the durability of the bridges because they are vulnerable to damage, e.g., cracks in link slabs over piers, deterioration, and damage to deck expansion joints at abutments.  
An effective solution to address these problems is to convert the simply supported beams with link slabs into continuous structures and eliminate the expansion joints to make the bridges jointless [9; 10; 11; 12]. Jointless bridges (JBs) are widely used not only in new bridges but also in retrofitting existing jointed bridges because JBs have a long service life and lower construction and maintenance costs. The three main types of JBs are integral bridges, semi-integral bridges, and deck extension bridges [13; 14; 15]. Among these, the integral bridge has several advantages, including superior structural integrity, durability, and resistance to the seismic hazards [16; 17]. Consequently, integral bridges are the preferred choice for both new constructions and retrofitting projects [18; 19]. However, significant flexibility in the substructure is generally required to accommodate longitudinal movements and to optimize truckload distribution and seismic response [20; 21; 22; 23; 24; 25; 26]. Existing jointed bridges with concrete piles of large stiffness may be preferred for retrofitting them into semi-integral bridges to reduce the additional forces and high stresses induced by the restrained longitudinal movement [27; 28; 29; 30]. The Jinpu Bridge discussed in this paper was a jointed bridge with concrete piers and was retrofitted into a semi-integral bridge.  
This paper describes the configuration and technical condition assessment of the Jinpu Bridge before retrofitting and the methodology and details for retrofitting.