Using of segmental box girder bridges with external prestressing is possible now due technique facilities and advantages. This paper constructed to highlights researches conducted to study behavior of segmental beams with dry and shear keyed joints. codes limitations, Structural modeling and analytical formulas are also illustrated. From the review, the investigations on segmental beams were still limited. The largest share of this limited researches conducted to study the behavior of segmental beams with external prestressing under moment and shear. limited models are suggested to calculate the capacity under moment and shear. Analysis of section at every loading stage is still required. Also, limited researches conducted to study the system behavior under combined moment, shear and torsion. from the review of this researches, there is no model suggested to calculate the ultimate capacity of the system under combined straining actions. The paper also shows that, the models suggested of internal unbonded prestressed segmental beams shows large variation in the results in case of combined straining actions. Previous studied parameters and important conclusions is illustrated. Future work and required parameter Also included.