DESIGN CRITERIA 1. INTRODUCTION This appendix summarizes the codes, standards, criteria, and practices that are generally used in the design and construction structural engineering system for the Sarker Steel Ltd. More specific project information will be developed during execution of the project to support detailed design, engineering, material procurement specification, and construction specifications. 2. CODES AND STANDARDS The design of structural engineering systems for the BEC will be in accordance with the laws, ordinances, and regulations of the Bangladesh government. The following codes and standards have been identified as applicable, in whole or in part, to structural engineering design and construction. American Institute of steel Construction (AISC): Manual of Steel Construction (1999)-3 rd revision. Specification for the Design, Fabrication and Erection off Structural Steel for building. Allowable Stress Design (ASD) AISC-1999. A-325 or equivalent Specification for structural fasteners as per American Society for Testing and Materials (ASTM) American Concrete Institute (ACI): ACI 318-2011 Building Code Requirements for Structural Concrete. American Welding Society(AWS): D1.1 Structural Welding Code-Steel. Load for engineering computation and capacity of the structural member is Assessed as per BNBC-1993/IBC-2006 Crane Loading and designing of crane girder as per Crane Manufacturers Association of America (CMAA). Structural Design Software: 3D modeling by STAAD Pro-v8i/ETABS 9.7.4 3. STRUCTURAL DESIGN CRITERIA
3.1 Topographic Elevations Site topographic elevations will be based on an elevation survey conducted using known local benchmark. 2. Temperature The design basis temperature for civil and structural engineering systems will be as follows: Maximum: 35 O C (At summer) Minimum: 10 O C (At winter) 4. DESIGN LOAD 4.1 General Design loads for structures and foundations will comply with all applicable building code requirements. Machineries load provided by the machine manufacturer. 4.2 Dead Loads Dead loads will consist of the weights of the structure and all equipment of a permanent or semipermanent nature including tanks, bins, wall panels, partitions, roofing, drains, piping, cable trays, bus ducts, and the contents of tanks and bins measured at full operating capacity. The contents of the tanks and bins, however, will not be considered as effective in resisting structure uplift due to wind forces; but will be considered as effective for seismic forces. 4.3 Live Loads Live loads will consist of uniform floor live loads and equipment live loads. Uniform live loads are assumed equivalent unit loads that are considered sufficient to provide for movable and transitory loads, such as the weights of people, portable equipment and tools, small equipment or parts, which may be moved over or placed on the floors during maintenance operations and planking. The uniform live loads will not be applied to floor areas that will be permanently occupied by equipment. Pitch Roofs: 12 pounds per square foot (psf) (0.57Kn/m 2 ). Floor and Platforms: As per occupancy category.
4.4 Wind Loads As per BNBC-1993 wind load contour maps, if the project location in Bangladesh. In case of export to other countries applicable local code for wind load will be applicable. 4.5 Seismic Loads As per BNBC-1993, if the project location in Bangladesh. In case of export to other countries applicable local code for seismic load will be applicable. 5. DESIGN BASES 5.1 General Reinforced concrete structures will be designed by the ultimate strength design method, in accordance with ACI 318, Building Code Requirements for structural concrete. Steel structure will be designed by the working stress method, in accordance with AISC specification for the Design, Fabrication and Erection of structural steel for Buildings. 5.2 Factor of Safety The factor of safety for all structures as per AISC/ACI 318-2011 and as per guided by structural stability research council SSRC. 5.3 Allowable Stresses Calculated stresses from governing loading combinations for structures and equipment supports will not exceed the allowable limits permitted by the applicable codes, standards, and specifications. 5.4 Load Factors and Load Combination For ASD Load Combination
Gravity Gravity+ wind Gravity+ Seismic Dead+ Wind Dead+ Seismic DL+LL DL+ LL+ W DL+LL+EQ 0.9 DL+W 0.9DL+EQ Allowable stresses may be increased 1/3 above the values otherwise provided when produced by wind or seismic loading, acting alone or in combination with the design dead and live loads. The load combination dead + lateral load is applicable when member is subjected to tremendous tension. 6. CONSTRUCTION MATERIALS 6.1 Reinforcing Steel Reinforcing steel bars for concrete will be deformed bars conforming ASTM A 615 Grade 75, Grade 60 and Grade 40 6.2 Structural and Miscellaneous Steel Structural and miscellaneous steel will generally conform to ASTM A 36, ASTM A 572-50 grade expect in special Situations where higher strength steel required. High-strength bolts, including nuts and washers, will conform to ASTM A 325 or equivalent. Bolt other than high-strength structural bolts will conform to ASTM 307, Grade A. 6.3 Other Materials Other material for construction, such as anchor bolts, shear connectors, concrete expansion anchors, embedded metal etc, will conform to industry standards and will be identified on engineering design drawings or specifications.
Page BreakExamples of few Projects constructed by Sarker Steel Limited SHED WITH MEZZANINE: Structural Analogy: The structure is designed as steel beam-column framing system including 5 R.C.C. slab in mezzanine decking. In the analysis beams & columns are idealized as 1-dimensional beam element and slab is idealized as 4-noded plate element.slab is also considered as rigid diaphragm which transferring the all other possible lateral force to the all lateral resistivity system according to the proportion of their stiffness. Some portion of the building consist rigid decking mezzanine floor and become very stiff comparable to other remaining flexible part of the building. Moreover the building of irregular planform and irregular vertical heights which is making to torsionally affected structure. So 3D structural model with proper choice and selection of bracing system is very important to minimize torsion which will be suffered due to exact loading.
External bracing is placed at the corner side of the building and roof system, to increase lateral stability and torsional potential structural system. Here double symmetric chevron bracing (Concentric bracing) is selected both in frame and roof that gives extra potential resistance and act as a semi-rigid roof diaphragm condition and protect the individual frames excessive relative movements and to control excessive sway of the whole framing structure assemblage, which is very essential for long story height of this type of building. Due to long length of column, the frame will be very flexible and that frame will experience vibrant shaking even at moderate intensity wind pressure. Without 3D model analysis, it is impossible to make economic, safe and efficient structure. SHED WITH CRANE: LLength-150meter Width-400meter Eave Height-21meter
Structural Analogy: External bracing is placed at the corner side of the building and roof system, to increase lateral stability and torsional potential structural system. Here double symmetric chevron bracing (Concentric bracing) is selected both in frame and roof that gives extra potential resistance and act as a semi-rigid roof diaphragm condition and protect the individual frames excessive relative movements and to control excessive sway of the whole framing structure assemblage, which is very essential for long story height of this type of building. Due to long length of column, the frame will be very flexible and that frame will experience vibrant shaking even at moderate intensity wind pressure. Without 3D model analysis, it is impossible to make economic, safe and efficient structure. MULTI STORIED:
Length-49meter Width-24meter Height-36meter STRUCTURAL ANALOGY: The structure is designed as steel beam-column framing system including 5 R.C.C. slab in mezzanine decking. In the analysis beams & columns are idealized as 1-dimensional beam element and slab is idealized as 4-noded plate element.slab is also considered as rigid diaphragm which transferring the all other possible lateral force to the all lateral resistivity system according to the proportion of their stiffness. External bracing is placed at the corner side of the building, to increase lateral stability and torsional potential structural system. Here double symmetric chevron bracing (Concentric bracing) is selected both in frame and roof that gives extra potential resistance and act as a semi-rigid roof diaphragm condition and protect the individual frames excessive relative movements and to control excessive sway of the whole framing structure assemblage, which is very essential for long story height of this type of building.