Roof Deck Research Articles

Occupants’ responses on rain noise underneath metal deck roof system

The design of metal deck roof system should incorporate some sound insulation materials if it were to insulate structure borne impact noise such as from the rain, transmitted into a building. The noise from the rain may affect the ambient noise level within the space underneath the roof thus affect the occupants’ comfort. Thus, this paper would like to examine the relationship between the annoyance responses with noise disturbance on occupants’ activities and side effects face by occupants’. The result reveals the impact from rain noise amplified by metal correlated with annoyances which cause uncomfortable condition to the occupant.

Thermal behavior in different roof coverings on classrooms

2 . Three classrooms were covered with asphaltic bitumen of three different colors (red tile, matte white and ebony black) the last one was covered with typical clay of the region. Two temperature sensors were installed in each classroom. The first one was fixed outside of the calssrooom at 0.40 m above the roof surface and the second one was installed 0.15 m below the ceiling. The temperature data were stored over ten minutes with a set of remote terminal units which form a wireless sensor network. The results showed significant differences in temperature between the four classrooms with a grade of significance of 0.05, and it showed that the color of the roof deck significantly influences the thermal behavior inside the classrooms. The influence of external temperature over the internal temperature was quantified with the r-Person coefficient, which was found at a mean value of 0.98.

Seismic design of low-rise steel buildings with flexible steel roof deck diaphragms - a Canadian perspective

Single-storey steel buildings in Canada are generally designed with a steel roof deck diaphragm to resist and transfer lateral loads to the vertical bracing system. Current Canadian seismic design provisions for these buildings are reviewed here with a focus on the design of the roof diaphragms. An equivalent static analysis method is generally used for these structures and comprehensive capacity design principles are applied to achieve a proper strength hierarchy in order to develop the intended yielding mechanism along the lateral load path. The method is illustrated with the help of a numerical example. The influence of roof diaphragm in-plane flexibility on the dynamic seismic response is discussed.

Elliptical Deformation of a Floating Roof Pontoon Due to Radial Second Mode of Sloshing (Effect of the Geometry of Pontoon Cross-Section on the Hoop Membrane Stress)

The radial second mode of sloshing in a circular cylindrical oil storage tank induces an out-of-plane deformation of the floating roof deck. The radial contraction of the deck due to this out-of-plane deformation contains modal components with circumferential wave numbers 0 and 2, thereby causing an elliptical deformation of the pontoon, which encloses the deck. In a previous paper, the stress caused by this elliptical deformation was analyzed by regarding the radial contraction of the deck as an enforced displacement of the whole pontoon. This paper presents an improved method for this stress analysis by considering the radial contraction of the deck as an enforced displacement of the joint between the deck and the pontoon. First, the effectiveness of the previous method in estimating the hoop membrane stress at the joint with the deck is confirmed by comparing the results obtained from the previous and improved method. Next, the improved method is used to predict also the other stress components in each portion of the pontoon. Numerical results reveal that the bending stresses are magnified locally near the joint with the deck and that the hoop membrane stress in the outer portion of the pontoon sensitively depends on the geometry of the cross-section of the pontoon. It is found that the hoop membrane stress near the joint between the outer rim and the top (or bottom) of the pontoon can be significantly reduced by increasing the slope of the top (or bottom) of the pontoon.

Shear capacity and tension capacity of arc-spot welds for multi-overlap deck panels

Arc-spot welds fabricated in multi-overlap configurations are found in roof deck construction when steel sheets are stacked at a sidelap or endlap. A welding technique that maximizes the quality of arc-spot welds fabricated through several layers of thick sheets is presented. Weld specimens were fabricated through 1, 2 or 4 layers of steel sheets with thicknesses ranging from 0.76 to 1.52 mm (22 to 16 gauge). The most important factors to control during the welding are the current (high intensity), the electrode type (E4311) and the welding technique. Various sheet steel/weld configurations found in roof deck construction were included. Adequate weld quality could be achieved in all cases except that welds were undersized when the ratio of the thickness of the underlying material to total sheet thickness was less than 0.7. A total of 72 tension tests and 107 shear tests were completed. Of those, 31 shear specimens were loaded with a reversed cyclic protocol to examine the behaviour of arc-spot welds subject to seismic loading. All other specimens were loaded under monotonically increasing displacement. The results were compared with the provisions of the CSA S136 North American Specification for the Design of Cold-Formed Steel Structural Members. The CSA S136 equations for shear and tension resistance of arc-spot welds are generally conservative, even for welds fabricated through multi-overlap configurations with total sheet steel thicknesses exceeding the 3.81 mm limit. Nonetheless, modifications to the equation for the effective diameter and to Equations E2.2.1.2-2, E2.2.2-1, and E2.2.2-2 are recommended.

Impact of Diaphragm Behavior on the Seismic Design of Low-Rise Steel Buildings

Modern building codes allow engineers to use reduced seismic loads in design provided that the seismic load resisting system (SLRS) of the structure is adequately designed and detailed to withstand strong ground shaking through ductile inelastic response. This approach has been adopted by the North American model codes which typically include special provisions to achieve satisfactory inelastic seismic performance. Single-story buildings often incorporate a steel roof deck diaphragm that is relied on to transfer lateral loads to the vertical bracing bents. The vertical braces are usually selected as the energy dissipating fuse element, while the diaphragm and other elements in the SLRS should be designed such that their capacity exceeds the nominal resistance of the braces. Steel bracing members designed for compression inherently possess significant reserve strength when loaded in tension, which means that large brace tension loads must be considered in the design of the surrounding protected structural components. Capacity design seismic provisions have led to the need for much thicker roof deck panels and more closely spaced diaphragm connection patterns compared with past practice in Canada. This paper describes the current U.S. seismic design approach and provides examples as it is applied to single-story buildings and their diaphragms. An overview of the related aspects of an on-going research project on the flexibility and ductility of the roof diaphragm in low-rise steel buildings is also included.

Flanking noise transmission in condominiums via steel roof deck.

Noise was found to transmit horizontally via a structure borne path. A lightweight roof consisting of ribbed steel deck spanned two adjacent loft-style condominium residential spaces. This noise transmission path significantly flanked the demising partition wall with known high-transmission loss. Two remedies were attempted to reduce transmission, by adding concrete on top of the roof deck. One remedy was successful.

Flanking paths associated with exposed roof decks in condominiums.

An award winning residential/commercial condominium project featured two-story loft condominiums with an industrial look. The building was constructed with steel structure, exposed concrete on metal deck floors, and an exposed metal deck roof. Condominiums were separated by gypsum board on metal stud walls. A number of owners in the building complained of poor sound isolation from adjacent units. Field tests showed that sound isolation of the walls fell below expectations for the design. Subsequent investigation showed that a variety of structureborne and airborne flanking paths contributed to poor sound isolation. Improving sound isolation required a combination of conventional and creative methods.

Steel Hexagonal Honeycomb Core Equivalent Elastic Moduli for Bridge Deck Sandwich Panels

Glass fiber-reinforced polymer (GFRP) materials possess inherently high strength-to-weight ratios, but their effective elastic moduli are low relative to civil engineering (CE) construction materials. While elastic modulus may be comparable to that of some CE materials, the lower shear modulus adversely affects stiffness. As a result, serviceability issues are what govern GFRP deck design in the CE bridge industry. An innovative solution to increase the stiffness of a commercial GFRP reinforced-sinusoidal honeycomb sandwich panel was proposed; this solution would completely replace the GFRP honeycomb core with a hexagonal honeycomb core constructed from commercial steel roof decking. The purpose of this study was to perform small-scale tests to characterize the steel hexagonal honeycomb core equivalent elastic moduli in an effort to simplify the modeling of the core. The steel core equivalent moduli experimental results were compared with theoretical hexagonal honeycomb elastic modulus equations from the literature, demonstrating the applicability of the theoretical equations to the steel honeycomb core. Core equivalent elastic modulus equations were then proposed to model and characterize the steel hexagonal honeycomb as applicable to sandwich panel design. The equivalent honeycomb core will enable an efficient sandwich panel stiffness design technique, both for structural analysis methods (i.e., hand calculations) and finite-element analysis procedures.

Push-off tests on pin-connected shear studs with composite steel–concrete beams

A new stud system fastened with high strength pins was investigated experimentally in this paper. This system is reported to be the fastest and the most economical method for installing studs to steel roof and floor decking in composite construction. It is 5–10 times faster than welding, screwing, or using powder actuated tools, which will directly reduce the fastening cost. These advantages would make significant contribution to the popularity of composite construction. The shear capacity of headed studs in composite steel–concrete beams has been determined experimentally in seven full-scale push-off tests. The tests were used to study the strength and ductility of the proposed stud system. Maximum resistances from the experimental tests are compared with the predictions of EC 4 and results from other researchers. The capacity of the stud is reduced due to fracture of the pins that occur before the shear stud had yielded. The proposed stud system can be improved further by increasing the size and the strength of the pins and base plate.

Finite Element Modeling of Single Lap Shear Screw Connection in Steel Sheeting in Fire

The load bearing steel deck is used in insulated metal deck roofing system for industrial buildings with low- pitched roof areas. The steel sheeting sections are manufactured with cold forming from thin steel strip and are attached to the underlying purlins or more commonly straight to the steel trusses by self-drilling or self-tapping screws. The behavior of sheeting connections is important in fire especially when the sheeting is in catenary action and tensile forces are devel- oped at supports where the screw connectors are located. A 3D finite element model is created using ABAQUS software to simulate the single lap screw connections connecting thinner sheet (0.8 mm) to thicker sheet (10 mm) under static shear at both room and high temperatures. This model considers the material nonlinearity, large deformation and contact behav- ior. The connection model is analyzed through the elastic and plastic ranges up to failure. The analysis reveals that the failure modes of the connection for both room and elevated temperatures are bearing failure of the thinner sheet. The load bearing capacity of the connections depends on the friction between the washer and the thinner sheet, the direct bearing of the screw shank against the thinner sheet and the postbuckling resistance of thinner sheet. Degradation of material at ele- vated temperature further reduces the strength and stiffness of the connections. This connection model can be taken as a component model in the analysis of the behavior of steel sheeting system in fire, which is highly non-linear so as to save the computing time.

Impact of suspended acoustical ceilings on the fire performance of open spaces.

An architectural design trend referred to as the “exposed structure” look is becoming increasingly popular due to a number of emerging design factors. In some cases, there is a desire to expose the overhead mechanical systems and roof deck, thus providing a feeling of spaciousness and economy. Or, in other cases, the desire for openness is driven by the installation of underfloor air distribution, in which case a traditional overhead ceiling is not needed to cover plenum mechanicals. The architects and building owners must, however, be reminded that the occupant safety, satisfaction, and performance will often be negatively impacted by these architectural design decisions. In particular, the response time of fire safety devices may be adversely affected, as shown by simulation tests.

Influence of nonstructural components on roof diaphragm stiffness and fundamental periods of single-storey steel buildings

The stiffening effect of nonstructural roofing components on the in-plane shear stiffness of metal roof deck diaphragms was studied. Tests were performed to determine the properties of the non-structural roofing materials and the typical diaphragm connectors. A linear elastic FE model was used to establish stiffness values for common diaphragm configurations, and the results were applied to evaluate the impact of nonstructural roofing elements on the fundamental period of vibration of single-storey steel buildings. The shear stiffness increase due to the nonstructural components was found to be more pronounced for the flexible steel deck diaphragms. The influence on the period of vibration was negligible for most of the buildings studied.

TESTING AND CALCULATING THREE‐HINGE SUSPENSION STRUCTURES OF HOLLOW CONCRETE‐FILLED STEEL TUBULAR MEMBERS

Recently in the research publications an information about a new type of suspended straight‐line 3‐hinge roof structures has appeared. In this sources it was stressed that straight‐line elements is easy to manufacture and erect, roof decking service conditions are good. In the world building practice during last 30 years very effective composite structures were introduced, even hollow concrete‐filled steel tubular members. At this time no information about the application of such members for suspended roofs was obtained. In some sources very simple straight‐line suspended roofs structures were analysed, and for these shapes an effective centrifuged hollow concrete‐filled steel tubular members may be successfully applied. These members do not require additional roof stabilisation. These composite ropes may be attributed to the elements of final flexural stiffness, and they are effective and simple to decrease deflections of a suspended roof. However, for such composite ropes methods of their calculations must be developed. Investigations made into the deformation properties and methods of deflection, definition of straight‐line circular hollow concrete‐filled steel tubular members allows to declare a possibility of useful application of such members as ones of final flexural stiffness in suspended roof structures.

Combination sound and vibration isolation curb for rooftop air-handling systems

This paper introduces the new Model ESSR Sound and Vibration Isolation Curb manufactured by Kinetics Noise Control, Inc. This product was specially designed to address all of the common transmission paths associated with noise and vibration sources from roof-mounted air-handling equipment. These include: reduction of airborne fan noise in supply and return air ductwork, reduction of duct rumble and breakout noise, reduction of direct airborne sound transmission through the roof deck, and reduction of vibration and structure-borne noise transmission to the building structure. Upgrade options are available for increased seismic restraint and wind-load protection. The advantages of this new system over the conventional approach of installing separate duct silencers in the room ceiling space below the rooftop unit are discussed. Several case studies are presented with the emphasis on completed projects pertaining to classrooms and school auditorium applications. Some success has also been achieved by adding active noise control components to improve low-frequency attenuation. This is an innovative product designed for conformance with the new classroom acoustics standard ANSI S12.60.

Helix Pedestrian Bridge

Amgen Incorporated, one of the world's largest biotechnology firms, recently developed a new research center on the Elliot Bay waterfront of Seattle, Washington. As part of the research center, a pedestrian bridge was built to connect the campus with a major transportation corridor. The owner's goal for the new pedestrian bridge was to create a signature gateway to Amgen's campus. The pedestrian bridge is a three-arch structure that depicts a three-dimensional helix. The overall shape of the bridge both reflects the helical DNA that connects all life and references the vital research under way at Amgen. The arches create the outline of the basic DNA helix, and the deck support and roof trusses complete the remaining components of the helix. The abstract double helix provided many design and construction challenges. The slim profile, large enclosed areas, and suspended deck meant wind and pedestrian vibration would be critical design considerations. The unique shape made it difficult to apply the standard building or bridge design codes. The contractor was faced with erecting this twisting structure over active railroad tracks while meeting tight geometric specifications. The bridge stands today as a testimony to the owner's vision, teamwork, innovation in bridge design, and creative construction techniques. The bridge combines both form and function to show how an ordinary pedestrian bridge can become an extraordinary statement while serving its intended function. The project has won broad community support in the few months that it has been open.

2209 地震時動揺を考慮した石油タンクのダブルデッキ浮屋根の強度評価(OS13 貯槽の防災と設計I)

Structural integrity assessment method for floating roof of oil tank against semi-long period (2-15 sec.) ground motion is presented. To obtain the roof motion and maximum dynamic pressure profile loaded on lower roof deck from oscillating oil during earthquake, structure-fluid coupled analysis between roof and oil was conducted with actual waveform of the Tokachi-Oki earthquake in 2003. Detailed stress analysis with non-liner FEM for floating roof was performed to evaluate buckling and welded joint strength of floating roof component. It is concluded that strength assessment results of welded joint is good agreement with observed actual damage of oil tank.

The influence of Good air on architecture. A « Formal Cure » ? The appearance of the Alpine sanatorium in Switzerland, 1880-1914

Abstract : Beginning in 1890, the development of health tourism saw the construction of many sanatoria in the Swiss Alps. Their architects sought a kind of edifice that would be most suited to the needs of patients suffering from tuberculosis. A rational layout, sober facades, new and economical materials : these were the principal characteristics of sanatoria at the turn of the century. Around 1910, the appearance of more specific models responded to the evolution of cures, and the invention of heliotherapy in particular. One such example was the Freilufihaus, a clinic featuring stepped balconies and roof deck solaria. These architectural models prefigured the Terrassenbau of the Twenties, of which the Passy sanatoria are the most interesting examples.

ANALYSIS, TESTING AND DESIGN OF STEEL ROOF DECK DIAPHRAGMS FOR DUCTILE EARTHQUAKE RESISTANCE

An experimental program was conducted to study the inelastic response of steel roof deck diaphragms for low-rise steel buildings subjected to seismic loading. Tests were performed on 3.6 m×6.1 m diaphragm specimens made of corrugated steel deck panels. The parameters examined were the thickness and configuration of the sheet steel panels, the type and spacing of the fasteners, the applied loading history and the influence of end lap joints. Diaphragms built with screwed side lap fasteners and nailed deck-to-frame connectors exhibited a pinched hysteretic behaviour, but could sustain large inelastic deformation cycles with limited strength degradation. This type of diaphragm construction could be designed to resist earthquake effects in the inelastic range. Higher shear resistance and less pinching was observed for systems that included welded with washer connections. However, their strength decreased rapidly after the peak load was reached, and hence, these systems should be designed for limited inelastic response. Deck systems with button punched side laps and frame welds without washers showed a brittle response and should be designed to remain elastic under severe earthquake motions. The inelastic demand was found to increase when the spacing of the fasteners was reduced. Specimens constructed with an internal overlap joint exhibited extensive warping of the cross section mainly due to the shorter panel length.

New Hybrid Precast Concrete Building Provides Optimum Solution for Metal Recycler

When a St. Louis, Missouri, company needed expanded facilities for its metal recycling operations, the contractor suggested a new hybrid precast concrete building system for fast-track construction of a facility that would provide durable open space for heavy equipment. Prestressed Casting Company designed a structure with loadbearing precast concrete wall panels and long-span double-tee frames in conjunction with a bar joist and metal deck roof system. The minimal cost premium for the hybrid precast solution (over a standard metal-framed structure) provided important additional value in early occupancy and a more functional and durable facility.