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Journal : Journal of the Civil Engineering Forum

Cold-Formed Steel Truss Roof Structure Failure Considering Seismic Load and Buckling Analysis Muslikh; Iman, Miftahul
Journal of the Civil Engineering Forum Vol. 12 No. 1 (January 2026)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jcef.13069

Abstract

There were many incidents of cold-formed steel roof truss structures in the last 5 years in Indonesia. Various kinds of allegations have been addressed to cold-formed steel material applications especially in the case of seismic resistance. Some of them concern the authenticity of the steel material itself and the selection of cold formed steel material. On the other hand, recently, people have installed (assembled) cold-formed steel trusses without involving a certified cold-formed steel applicator. This research is based on a numerical study that modeled the collapse pattern of cold-formed steel truss roof structures by considering buckling failure and the seismic load capacity. The cold-formed steel roof truss structure was modeled with 3D-truss elements in two model types: the overall structure and a single compression member element in 3D solid idealization. Buckling analysis with eigenvalue and nonlinear static analysis was performed to evaluate the critical load (Pcr). The buckling mode shape also was also compared with the mode shape of modal analysis. This research also evaluated the effect of seismic load on the overall cold-formed steel truss structure and the slenderness of the compression member. The numerical simulation of cyclic loading on the single compression member was conducted in this research. The numerical analysis results showed that cold-formed steel roof truss structure have high vulnerability to seismic hazard effect. The cold-formed steel material has lower ductility than hot rolled steel material. This causes the lateral displacement that occurs to be lower than the displacement produced by the hysteretic curve of numerical cyclic simulation. This research also evaluated the dynamic properties, such as frequency, periods, and mode shapes, of some typical cold-formed steel for roof truss structure.
A Flexural Behavior of Full-Scale RC Beam Strengthened Using Glass Fiber Reinforced Polymer: Experimental Research Putri, Oktalia Wuranti; Setiawan, Angga Fajar; Siswosukarto, Suprapto; Muflikhun, Muhammad Akhsin; Nor, Noorsuhada Md; Muslikh
Journal of the Civil Engineering Forum Vol. 12 No. 2 (May 2026)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jcef.22499

Abstract

Reinforced Concrete (RC) structures, though strong and economical, may need to be strengthened due to increased load demand for upgraded room functions. Strengthening an RC beam element with Glass Fiber Reinforced Polymer (GFRP) offers flexural strength enhancement, corrosion resistance, and cost efficiency. However, the study that considers the full-scale dimension of a beam strengthened with GFRP is still limited. Therefore, more studies on the flexural strength enhancement of RC beams with GFRP need to be conducted. This research investigated the flexural performance of full-scale RC beams strengthened with externally bonded GFRP. This study involved testing five beam specimens, each with a different number of GFRP layers attached to the outermost tensile zone of the cross-section. Flexural testing was conducted using a four-point bending setup with a loading–unloading scheme to capture the specimens’ elastoplastic behavior, considering recovery during unloading. The analyzed parameters included stiffness, yield strength, debonding strength, ultimate strength, and ductility. Furthermore, the flexural strength was predicted through analytical calculations based on the fiber section method, while the shear strength was estimated following the ACI 318M-14 code. The experimental results showed that GFRP strengthening considerably increased stiffness and first flexural strength of RC beams as a proportion of the number of layers during the pre-debonding state. Despite the debonding occurrence initiating a temporary lapse in the role of GFRP at 0.67% to 0.93% of displacement-span-ratio, it decreased the flexural resistance momentarily. Then, the strengthened beams with two-to-four-layer GFRP still exhibited second ultimate flexural strength enhancement within the range 14.35% to 39.22%. Furthermore, GFRP strengthening generally preserved beam ductility at the second ultimate flexural strength due to the catenary action from debonded GFRP in the plastic hinge zone. Thus, additional GFRP for strengthening RC beams could be effective in the case of a positive bending moment to enhance the stiffness, strength, and ductility