International Journal of Engineering Research and Technology. ISSN 0974-3154 Vol.13, No.4 (2020), pp. 631-636 © International Research Publication House. https://dx.doi.org/10.37624/IJERT/13.4.2020.631-636 631 Effect of Reinforcement Details on Precast Bridge Frames of Bamboo Reinforced Concrete to Load Capacity and Crack Patterns Muhtar 1 , Amri Gunasti 2 , Adhitya Surya Manggala 3 , Ardhi Fathonisyam Putra Nusant 4 , Hanafi 5 , Agung Nilogiri 6 1,2,3,4,5,6 University of Muhammadiyah Jember, Jember, 68121, Indonesia. ORCIDs: 0000-0002-5734-2728 (Muhtar), 0000-0002-9732-5869 (Amri), 0000-0002-5386-123x (Adhitya), 0000-0001-8183-5875 (Ardhi), 0000-0002-5616-4384 (Hanafi), 0000-0001-7250-0432 (Agung) Abstract Truss structures are usually only considered to accept compressive axial forces and tensile axial forces. Structure node point is assumed to be a joint that cannot receive moments. But it's not the case with truss structures from concrete, large self-weight causes moment, so that "Truss" structures from concrete are called "Frame" structures. This study aims to increase the capacity and crack pattern of the precast bridge frame from bamboo reinforced concrete with different reinforcement variants. Two frames are made with the focus of observation on the underside element of the frame. Frame variations consist of one frame with symmetry reinforcement as the joint frame model or “truss model”, one frame with flexural reinforcement as the rigid portal model or “frame model”. Testing is done with two load points at the knot on the top side of the frame. The test results show that the bamboo reinforced concrete frame with a rigid portal model or "frame model" has stiffness and higher load capacity than the stiffness of the joint frame model or "truss model". Large self-weight will cause the moment can not be zero on each element, and the knot point behaves elastic clasps. However, a reinforced concrete frame does not fully behave as a rigid portal, this is evidenced by the crack pattern similar to the crack pattern on the "truss model", namely cracking perpendicular to the stem element and propagate across the tensile element. Keywords: Precast Bridge Frame, Bamboo Reinforced Concrete, Crack Pattern, Truss Model, Frame Model I. INTRODUCTION Bamboo as a construction material has been widely used especially in rural areas that produce bamboo. The utilization of bamboo is usually used as a warehouse construction framework, simple house construction, non-permanent bridges, and others. Bamboo as a material renewable and environmentally friendly has been widely researched as a concrete reinforcement by [1], [2], [3], [4], [5], [6], [7], [8], and [13]. The use of bamboo as truss reinforcement has not been much researched. Dewi et al. (2011) [9] examined bamboo as a reinforcement material for simple house horses and his research showed that the cracking patterns that occur are due to the flexural effect. The main principle of the truss as a load-bearing structure is the arrangement of the truss elements into triangular configurations so that it becomes a stable shape. External load is a centralized load that works at knot points. This external load effect causes pure tensile force and compressive force on each truss element. The truss structure from reinforced concrete has an uncertain element of the knot point so that the compressive force and tensile force are not completely pure axial forces. This is due to the restraint at the knot point and its considerable weight. Theoretically, the maximum force that can be resistant by every bamboo reinforced concrete frame element is the load that causes the f'c stress on the concrete. The frame element with area Ag with width b and height h, area of reinforcement of Ab bamboo, then the net area of the cross-section of the bamboo reinforced concrete frame element is Ag-Ab. The maximum centric load capacity on a bamboo reinforced concrete frame can be obtained by adding concrete contributions, ie (Ag-Ab)f’c and the contribution of Abfyb bamboo. Thus, the maximum centric load capacity, Po can be stated as follows Equation (1).   b yb c b g o xA f f A A P    ' (1) Centric load causes the pressure to be evenly distributed on the cross-section so that the stress and strain will be the same throughout the cross-section. In reinforced concrete design, the assumption of concrete tensile strength is ignored because the tensile strength of the concrete is small so that the tensile force is fully retained by the reinforcement. However, at elastic loads, before cracking occurs in the concrete, the tensile strength is restraint by the concrete and bamboo reinforcement. So that the tensile capacity of frame elements is calculated by calculating the tensile strength of concrete such as Equation (2) [9], [10].   bamboo tr bamboo g cr o A f A A f P . 85 , 0 '    (2) where f'cr = concrete tensile stress, ftr = tensile yield stress of bamboo, Ag = Area of cross section of concrete elements, Abamboo = area of bamboo reinforcement.