Optimal depth selection of composite tubular-floor trusses based on cost estimation

The significance of this study initiates from the need to produce a selection guidance on the span range, span-to-depth ratio and scheme of the composite floor truss system to provide optimum performance and cost effectiveness for a particular application area. With this objective a parametric study was designed, based on three parallel chord trusses (Pratt, Howe, and Warren) using Rectangular Hollow Structural Shapes, a constant panel size of 2.5 m, four composite floor European-profiles and a range of load intensities. Hence, the span-to-depth ratios, RS/D, and dead-to-live load ratios, RDL/LL, were ranged from 3 to 27 and 0.84 to 3.22, respectively, for each truss type. The optimization was performed by using the design results of RFEM (2018) software for approximately 675 composite floor trusses with the objective of selecting optimal depth for each truss model. In addition, this paper attempts to introduce a cost function by considering the material, fabrication and painting costs and comparative figures allowing the design to be tailored with a focus on cost reduction. Accordingly, for all truss types, span-to-depth ratio of 9 to 12 with a span range of 7 to 23 m provides the most cost effective solution. Structural steel and the welding process are the two parameters that are found to have the highest impact on total cost.

Kajian Model Struktur Rangka Atap Baja Canai Dingin Studi Kasus Gedung Limbah UBP Saguling. (Hal. 1-8)

ABSTRAKBaja canai dingin merupakan salah satu material yang dianggap memiliki waktu konstruksi yang cepat, aman, nyaman, dan tidak merusak estetika dari bangunan. Baja canai dingin memiliki dimensi yang tipis dan ringan namun memiliki kekuatan tarik dan tekan yang tidak kalah dengan baja konvensional. Studi banding dilakukan untuk mengetahui model rangka atap yang paling ringan serta memenuhi syarat nilai kekuatan dan kekakuan. Profil baja yang digunakan adalah C 150x50x20x2,8. Berdasarkan perhitungan kapasitas desain dan kapasitas penampang untuk struktur rangka atap baja canai dingin, maka rangka atap yang dipilih adalah Scissoels. Room In Attic merupakan rangka atap yang paling ringan dengan berat sebesar 72,24% dari jenis rangka atap terberat yaitu Valuated Paralel Chord. Batas kelangsingan untuk batang yang mengalami tarik adalahle le/r < 300 dan untuk batang tekan adalah le/r < 200Kata kunci: baja canai dingin, tarik, tekan, kekakuan, kekuatan, rangka atap, ringan ABSTRACTCold rolled steel is one material that is considered to have a fast construction time, safe, comfortable, and does not damage the aesthetics of the building. Cold rolled steel has dimensions that are thin and light but have tensile strength and tap that is not inferior to conventional steel. The comparative study was conducted to find out the most lightweight roof frame model and qualify for strength and stiffness values. The steel profile used is C 150x50x20x2,8. Based on the calculation of the design capacity and the cross-sectional capacity for cold rolled steel roof frame structure, the selected roof frame is Scissoels. Room In Attic is the lightest roof truss with a weight of 72.24% of the heaviest roof frame types are Valuated Parallel Chord. The slimness limit for a tensile rod is le/r < 300 and for the press rod is le/r < 200Keywords: cold rolled steel, tensile, compressive, stiffness, strength, roof truss, undermanding

SPATIAL STRUCTURES OF CLOSED PROFILES

The article presents a new design of steel space trusses, arches, frames of complex application, the main advantages of which are lightness, durability of plane, cost efficiency, reliability, reduction of construction period and investment cycle, energy savings at manufacture, transportation and construction. Based on the previously performed experimental and theoretic studies, the expediency of using box-shaped section parallel chord trusses has been proved. Therefore, new constructive decisions for light efficient trusses, arches, frames that can be used at erection of civil and industrial objects are presented below. The suggested efficient structure of a steel truss with spatial upper chord, using tubes or rectangular hollow box-shaped sections, steel trifurcate spatial truss construction, spatial arch truss, spatial arch. Considered the use of closed cross-sections for spatial arch elements. It has been revealed that using the two-hinges spatial frame the construction cost of a building can be reduced due to reducing of the basement’s dimensions.

Strength and stiffness of glulam trusses with punched metal plated joints

Several Canadian wood truss manufacturers expressed a need to develop technical information to initiate the fabrication and acceptance of wood trusses made with glued-laminated timber (glulam) members and connected by punched metal plates. In collaboration with industrial participants, Forintek Canada Corp. developed a program for testing and analysis of metal plated glulam trusses. Twelve 3/12 pitched chord trusses and three parallel chord trusses, all 13.7 m long, were designed by three different plate manufacturers. All truss fabrication took place at a single truss manufacturing plant. Trusses composed of 79 mm wide and 152-229 mm deep glulam members connected by 16-gauge punched metal plates were tested to failure. The ratio of ultimate to design load averaged 3.5, and varied between 2.7 and 4.4. Both wood and plate failure modes were observed. The results suggest that the sizes of glulam members used in this study are structurally suitable for use with 16-gauge metal connector plates. Key words: wood, trusses, glued-laminated timber, truss plates, strength, stiffness.