http://yetl.yabesh.ir/yetl1/handle/yetl/19021 2026-05-02T20:08:47Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309235 Proactive Enhancement on Fatigue Performance of Cracked Diaphragm in Steel Bridge Employing Fe-SMA Yapeng Wu; Xuhong Qiang; Xu Jiang Fatigue cracks are prone to occur at the arc-shaped cutouts of the diaphragms in orthotropic steel deck bridges. Based on the crack-stop holes, the China-made ferrous-based shape memory alloy (Fe-SMA) plates are employed for repairing the cracked diaphragm cutouts, utilizing their inherent stiffness and shape memory effect. In this experimental study, a total of eight diaphragm specimens were designed for fatigue tests. Among these, three specimens were repaired solely by the crack-stop holes, while five specimens were repaired by the Fe-SMA plates covering crack-stop holes. By reinforcing the diaphragm cutouts with Fe-SMA plates, significant local stiffness and compressive stresses can be introduced at the cracked regions, which can effectively reduce the stress concentration, delay the initiation of fatigue cracks, and suppress crack propagation after secondary cracking. Via comparison, it has been noted that the fatigue life of specimens repaired by Fe-SMA plates is 3.73–12.68 times that of specimens repaired solely by crack-stop holes, and the enhancing effect of bonding Fe-SMA plates is better than that of bonding carbon fiber–reinforced polymer (CFRP) sheets and SMA/CFRP composite patches. The fatigue strength of the reinforced diaphragms significantly exceeds the fatigue grade of current design standards, indicating that the proposed novel method of bonding Fe-SMA based on crack-stop holes is effective and practical for actively repairing fatigue cracks of diaphragms in steel bridges. The fatigue problems of steel bridges are becoming increasingly prominent owing to influencing factors such as welding defects, stress concentration, and residual stress. Under long-term service conditions, fatigue cracking usually occurs at the diaphragm arc-shape cutouts in the orthotropic steel bridge decks subjected to vehicle-induced vibration and cyclical wheel load. The China-made ferrous-based shape memory alloy (Fe-SMA) is employed to actively repair fatigue cracks in steel bridges through adhesion, which offers the advantage of eliminating the reliance on traditional prestressing techniques that require complex equipment and expensive anchors. When applying Fe-SMA for the proactive repair of fatigue-cracked orthotropic steel deck bridge diaphragms, activating Fe-SMA can introduce precompressive stresses of about 60 MPa at the edge of crack-stop holes, based on the increase of local stiffness at the cracked region. The feasibility and effectiveness of the method of covering crack-stop holes with Fe-SMA plates have been verified through the actual repair applications of cracked diaphragm cutouts in the Sutong Bridge and other kilometer-level steel bridges. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309234 Finding the Completed Bridge State of Suspension Bridges with Short Extended Spans Based on Specified Hanger Forces Zhen-ping Wang; Wen-ming Zhang; Xiao-yi Zhang; Gen-min Tian A suspension bridge with short extended spans is a distinct and novel bridge type combining large stiffness and economic efficiency. This form of suspension bridge has been extensively built to carry trains. However, due to extended spans, hanger forces cannot be determined using the multipoint rigidly supported continuous beam method, a conventional method to determine the completed bridge state of suspension bridges without short extended spans. Addressing this problem, we propose two analytical approaches, namely, the precambering (PC) approach and the equivalent temperature load (ETL) approach. First, specified hanger forces are imposed on the three-span continuous beam, which is the main beam. The bending moment and deflection of the main beam caused by hanger forces and self-weight are solved. Next, the opposite number is taken of the y-coordinates of the node corresponding to the deflected geometric configuration of the main beam to obtain the geometric configuration of a curved beam with a predeflection (the PC approach). Another approach is to perform a reverse calculation of gradient temperature load from the estimated bending moments of each cross section of the main beam (the ETL approach). After that, the catenary theory is used to solve the geometric configuration of the main cable under the action of specified hanger forces. Finally, the initial strain of the hanger is solved. So far, we have obtained the analytical data of the entire bridge as inputs of the finite-element model, which is run only once to yield the completed bridge state. The results are satisfactory using either proposed approach. There is no need for iteration, which is otherwise tedious and time-consuming. The proposed approaches prove to have higher universality and practicability. The feasibility and accuracy of the analytical approaches are verified through an engineering example, which is a single-main-span suspension bridge with two short extended spans and a span length layout of 100 m + 1,080 m + 100 m. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309232 Extended Monitoring of Earth Pressures Behind a 90 m Integral Bridge Douglas G. Morley; Sarah A. Skorpen; Jurie F. Adendorff; Elsabe P. Kearsley; S. W. Jacobsz; Gopal S. P. Madabhushi Despite the popularity of integral bridges, long-term field data are required to better understand the soil strain ratcheting behavior that occurs with thermal cycles. This work presents over 6 years of field data collected from the Van Zylspruit Bridge, a 90-m-long integral bridge in South Africa. Sensors recording temperature, abutment movement, earth pressure, and soil water content were used to understand bridge behavior. Results show only a small increase in earth pressure over time, far less than that expected from physical modeling. One explanation for this may be the smaller-than-expected thermal movements recorded. Further possibilities were investigated through the small-scale modeling of a 1.5-m RC abutment, from which it was found that the starting position of the abutment and concrete drying shrinkage are both unlikely to contribute to the pressure buildup, while soil water content may play a part through the suctions generated. Based on these findings, the strain ratcheting of earth pressures in the field appears to be less severe than modeling efforts would suggest. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309231 Performance Evaluation of Semi-Integral Abutment Bridge Ends Based on Approach Slab Details Shadi Azad; Behrouz Shafei Semi-integral abutments help increase the service life of bridges by eliminating the issues associated with the use of expansion joints. However, the behavior of such abutments under service loads has complexities, especially in their connections to approach slabs. This motivated the current study to systematically investigate the in-service performance of semi-integral abutment bridges through a holistic suite of visual inspections, long-term monitoring programs, and numerical analyses. For this purpose, nine bridges were visually inspected to identify common problems associated with semi-integral abutments, including joint issues, embankment erosion, cracks in approach slabs, and water leakage. Additionally, two bridges were instrumented with various sensors at the time of construction and monitored to understand their long-term behavior under service loads. This was with a focus on top and bottom approach slab strains, longitudinal and transverse abutment displacements, and earth pressures on abutment walls. Two bridges with a high skew angle was further studied numerically in four different design configurations to evaluate the stress, strain, and displacement distributions in the approach slab and tie bars. The numerical investigations also assessed the bridge end’s response to embankment settlement, given the frequent occurrence of settlement-related issues. The study’s results and findings provided new insights into key structural response measures paired with relevant recommendations. The outcome facilitates the design and assessment of semi-integral abutment bridge ends, taking into account various approach slab details. 2025-01-01T00:00:00Z