A warehouse with a mezzanine floor inside that building. Roof design for good performance of the roof system is highly relevant to maintaining the integrity of the roofing membrane and drainage system.
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Problems with the roof will affect the ponding, which is related to the strength and stiffness of the roof structure. The designer must consider the stability of the Roof structure in case of waterlogging
Instability when water is trapped (ponding stability). The design standards for structural steel buildings by the resistance and load factor method of the Engineering Institute of Thailand (EIT 1020) in Chapter 11.2 stated that “There must be an analytical The structure of the roof system Both in terms of power and stability in the event of waterlogging. Unless the roof is sloped enough or there is a good drainage system that will not cause water logging. is what the designer The structure must be considered on the basic principles that are important. Water is a fluid that can multiply or transform. along the surface of the roof that can be hidden and a source of water It’s something that can’t be controlled. for example Rainwater, which is considered a natural occurrence. When water is trapped on the roof The building owner should notify an engineer or architect with expertise to inspect. because water logging affects the stability of Structure and safety of building occupants The major causes of water hearing can be as follows.
- Deflection from the fixed weight of the roof structure
- Deflection of structural members Which is the part that lies between the points that are lower than the end points of that building
- The deflection of the part of the structure that supports the equipment or tools installed to the roof structure.
- 4. Structural building elements with curved backs through thinking back home
- Clogged drains
- Powder railing at the edge of the roof without drainage holes
- Railing panel at the edge of the roof where the water drain is clogged
- Shielding of water waiting to drain, which is part of the roof sap flow control design.
- Low-slope roof which causes water retention due to the hydraulic gradient
Rain water logging causes deflection of the roof system. which leads to an increase in the amount or weight of water on the roof structure The additional water retained will cause deflection and increase the capacity, which if not corrected, will continue to occur. The purpose of the waterlogging inspection is to ensure that the cause of the waterlogging is not an event of a failure of the designer or contractor and does not damage the overall structure of the water logging that occurs
Requirements of the Engineering Institute of Thailand in the design standards of structural steel buildings or warehouses that use the mezzanine floor By resistance and payload multiplier (EIT 1020), Chapter 11, Section 112, to set the limits of consciousness. The nails of the building frame that stabilize the roof system are
In general, building design will take into account Equation 11.2-2, in which case there is no need to increase the stiffness of the roof sheet. Equation 11 2-1 in many cases means that the roof sheet is conscious. quite less and would like to add stiffness to that roof rather than considering the matter Ability to carry loads Because in most cases it is found that roof structures that do not meet Equation 11.2-2 can bear shearing stresses up to Fy according to the design requirements by the resistivity factor method and Payload (LRFO)
Requirements of the Engineering Institute of Thailand (EIT 1020) Procedure for checking stability When the water retained meets the requirements of the total cross-sectional stress, if the designer can control the stiffness in accordance with Equations 112-1 and 11.2.2, then there is no need to perform Check the total cutting stress. The process of this stability check depends on
- Calculation of deflection due to water accumulation in the area of main and secondary building members with orientation The body in the beginning when the water logging occurs. These deflections are considered as sine half-waves, which can be calculated accurately enough.
- Designed with resistance and load factor (LRFD) methods. And the load from rain was equal to 1.2 and the resistance multiplier (2) was equal to 1 for constant load.
- The behavior of the building element is in the elastic region, so the deflection is directly proportional to unit of force
- Rainwater entrapment stress is etched by the value of Fy (for LRFD method) minus the resulting stress. The building body when the quarantine begins depends on the schedule used.
It is important for the integrity of the roofing to consider 3 main issues together:
- Area of the roof
- The edge or edge of the roof
The characteristics of the roof that will be discussed below are metal roofs on the structure.
- metal roofs
Metal roofs are categorized according to their installation into two types: Thou Fastened roofs (TFR) and standing seam roofs (SSR). Standing here means A type of metal roof that is not attached to the supporting structure of the roof sheet (floating type), but only supports the roof sheet with clips hidden under the sheet and causes the roof to rise, but disappears. Does not have the characteristics of floating feature e) shall be provided as Fixed metal roof
The area of the metal roof must be divided into sections. As for the roof area, there will be the following practices. For the type of roof that has brackets that have a direction parallel to the roofing, the area will be limited to a length of about 30 to 60 meters in order to prevent leakage at the bracket due to elongation of bore hole Therefore, most steel structure building fabricators rely on placing purlins at appropriate distances for slotting) roof sheets. good deformation resistance Therefore, iron powder should not be used in conjunction with a type of roof system with fasteners. Tab-shaped roof The stand will have a theoretical limitation related to the maximum movement of the closing snapper. Which will have a limitation of distance from 45 to 76 meters. As for the consideration criteria or the limit of deflection of various types of structures, it will be considered compared to the span length (L) of the building members, referring to the requirements of International Building Code (IBC)