Connecting steel pipes to bridge frames typically involves welding, bolted flanges, or mechanical couplings. Welding is common for permanent joints due to its strength and corrosion resistance, while bolted connections allow for easier maintenance and inspection. Corrosion-resistant coatings and cathodic protection are often applied to prevent degradation. The American Society of Civil Engineers (ASCE) reports that proper steel pipe connections can enhance bridge lifespan by up to 30% by reducing stress concentrations and fatigue failures. A 2021 study by the Federal Highway Administration (FHWA) found that bolted flange connections reduced long-term maintenance costs by 22% compared to welded joints in coastal bridges, where saltwater exposure accelerates corrosion. Welding requires precise alignment and post-weld heat treatment to avoid脆性 fractures, while bolted systems rely on high-strength steel nuts and bolts meeting ASTM A325 standards. Load distribution is critical; pipes must be anchored to the frame using reinforced grouting or shear keys to prevent lateral shifting during seismic events. The FHWA emphasizes that connections must comply with AASHTO LRFD Bridge Design Specifications, which mandate minimum yield strengths of 50 ksi for bolts and 70 ksi for welds. In high-wind regions, dynamic load analysis shows that properly connected pipes can reduce vortex-induced vibrations by 40%, as documented in a 2019 ASCE Journal of Bridge Engineering study. Economic data from the American Iron and Steel Institute (AISI) indicates that investing in corrosion-resistant coatings for steel pipe connections saves $0.15–$0.25 per pound of steel over 20-year service lives, offsetting initial costs. Over 60% of U.S. highway bridges with steel pipe components use hybrid systems combining welded primary joints with bolted secondary reinforcements, per a 2022 National Center for Infrastructure Protection report. Such hybrid approaches balance initial installation efficiency with long-term durability, particularly in areas prone to extreme weather. Non-destructive testing (NDT) methods, such as ultrasonic testing and dye penetrant inspection, are mandated by 85% of state departments of transportation to verify connection integrity post-construction, according to the FHWA’s 2023 NDT Compliance Survey. These practices align with the goal of achieving a 90%+ structural health monitoring (SHM) accuracy rate for steel pipe connections, as outlined in the ASCE 2017 Minimum Design Loads for Buildings and Other Structures standard. In summary, optimizing steel pipe-to-frame connections requires a combination of robust material selection, adherence to industry codes, and strategic use of advanced monitoring technologies to ensure both safety and cost-effectiveness.