Analisis Desain Dan Konstruksi Jembatan Ngargosari Berbasis Investigasi Geoteknik Di Kabupaten Boyolali

The Ngargosari Bridge is a strategic infrastructure connecting Kiringan-Ngargosari in Ampel District, Boyolali Regency. This research analyzes the design and construction of a bridge with a total span of 30 meters (12m + 18m) based on comprehensive geotechnical investigation. Research methods include cone penetration tests at 4 location points, soil bearing capacity analysis, and structural design using a combination of reinforced concrete and steel. Investigation results show variations in hard soil depth between 1.2-4.2 meters with qc values reaching 180 kg/cm² in cohesive soil consisting of volcanic sandy clay. Structural design employs T-beam girders (40x80 cm) for the 12-meter span and IWF 600.200.11.17 steel profiles for the 18-meter span, with foundations adapted to local soil conditions. Material specifications include concrete grades fc’ 10-25 MPa and BjTS 420B reinforcing steel according to SNI standards. This research provides practical contributions to geotechnical data-based bridge design for volcanic soil conditions in Indonesia.