This article suggests a procedure for a technical diagnosis of a horizontally curved bridge (HCB). The structure is so significant in torsional warping and flexural actions that its response to the so-called ‘unusual component of internal forces’ bimoment, torsional warping, and flexural torsional effects is complicated to master. To understand the responses that need to be measured, large-span structures having different configurations of the cross-section, static, or dynamic loadings are intentionally combined. Firstly, a straight structure at the same span length and cross-section is studied as a comparative model; secondly, three finite element models of HCB with multi-cell and thin-walled cross-sections subjected to torsional and flexural are developed to get data of responses. By conducting a modal analysis and a simulated test with rather strong excitation at midspan, results indicate that it is relevant to install accelerometers at somewhere midspan and velocity transducers at supports; besides, flexural and torsional vibrations dominate simultaneously in the higher modes of curved structures. Some other findings are that the sharper the curvature is, the more notable the torsional vibration that appears in the first mode. Finally, the dynamic analysis for exploring the responses of the structure in the hope of finding a base for technical diagnosis of the structure using accelerometers, and strain gauges together with other remote instruments for displacement measuring tests, and non-destructive tests for the connection and status of assembly components. From these abovementioned results, some relevant locations, instrumentation design, and main technical specifications are suggested.