Field Measured Dynamic Effects and Load Distribution in a Prestressed Concrete Light Rail Bridge

Abstract

Live load performance of a recently constructed, prestressed concrete bridge was investigated to determine the Impact Factors (IMs), the Girder Distribution Factors (GDFs). The bridge was subjected to controlled static and dynamic loading using two Denver Transit Partners (DTP) electric-multiple-unit rail cars prior to a commuter rail line being placed into service. The rail cars travelled along northbound and southbound tracks of the four span, horizontally curved, bridge at various speeds. A total 24 tests were conducted and response was measured using a combination of strain sensors and accelerometers installed at critical sections on the supporting girders. Results for IMs and GDFs obtained from the field tests are presented. These results are also compared against relevant code provisions and these preliminary results indicated that IMs are insensitive to train speed and are smaller than investigated code provisions and that measured GDFs were different than those provided by these code provisions.

Evaluation of Prestressed Concrete Bridges under Light Rail Loading

“…Yuan et al 6 examined the behavior of prestressed concrete bridges (I-shape and box girders) subjected to light rail trains; however, the focus was on substructural responses. Khan et al 7 reported a preliminary field monitoring project with a bridge carrying light rail trains. The bridge consisted of four simply supported prestressed concrete girders at an average span of 95 ft (29 m).…”

Experimental Study on Dynamic Effects of a Long-span Railway Continuous Beam Bridge

“…In their study, the dynamic displacement were found to be as much as 20% larger than the corresponding static response, and the dynamic amplification factor (DAF) obtained from the moments reached a high value of 1.45. Khan et al [21] conducted field tests of a prestressed concrete simply supported beam bridge subjected to two electric-multiple-unit rail cars to determine the IMs, and the IMs were found to be insensitive to train speed and smaller than investigated code provisions. So far, much experimental research has been conducted to study the dynamic impact of railway arch bridges or simply supported bridges.…”