Roof Truss Research Articles

Raising the roof on design in Russia: Pulkovo airport

Pulkovo International airport near St Petersburg is nearing completion of a €1 billion redevelopment as a vital new gateway into Russia. Its new main terminal opened in December 2013 and by the end of 2015 the airport will have a capacity of 17 million passengers per year. It is also one of the first public–private partnership projects of its kind in Russia. Use of conventional construction techniques in innovative ways was a key factor in successful on-time completion of the new terminal building. Developing a flexible concrete frame allowed the contractor to work productively and continuously through the harsh Russian winters. In addition, early geometric studies developed a diagonal spanning roof truss system to realise the competition-winning architectural design. The Russian market has its own unique set of challenges and this paper outlines the techniques utilised to strike the right balance between local compliance and innovation to deliver a major international transport facility.

Dendrochronologická analýza krovu kostela Nanebevzetí Panny Marie a sv. Ondřeje ve Starém Hobzí

The work deals with dendrochronological analysis of the roof truss of parish church in the locality of Stare Hobzi. The dendrochronological analysis gave an integrated view on a complicated development of this building and it helped us to restore the succession of building adjustments performed on this building. The work is also to introduce the dendrochronology branch to people who participate on or direct perform building-historical research and to show them that it could be an essential helper in their work.

Stability and Load Bearing Capacity of a Bars with Built up Cross Section and Elastic Supports / Badania Stateczności I Nosności Prętów Złożonych Z Podporami Sprężystymi

Abstract The present paper is devoted to the numerical analysis and experimental tests of compressed bars with built-up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static analysis results, with material and geometrical nonlinearity, are presented for the bar with built-up cross section which was used as the top chord of the truss made in reality. Diagonals and verticals which are supports for the top chord between marginal joints were replaced by the elastic supports. The threshold stiffness (minimum stiffness) for the intermediate elastic supports which ensures maximum buckling load was appointed for the beam and shell model of the structure. The magnitude of limit load depended on length of the battens was calculated for models with initial geometric imperfections. The experimental tests results for the axially compressed bars with builtup cross section and elastic support are presented.

Analysis of Brace Stiffness Influence on Stability of the Truss

The paper is devoted to the numerical and experimental research of stability of a truss with side elastic supports at the top chord. The structure is a model of a real roof truss scaled by factor ¼. The linear buckling analysis and non-linear static analysis were carried out. The buckling length factor for the compressed top chord was calculated and the limit load for the imperfect truss shell model with respect to brace stiffness was obtained. The relation between brace normal force and loading of the truss is presented. The threshold stiffness of braces necessary to obtain the maximum buckling load was found. The truss load bearing capacity obtained from numerical analysis was compared with Eurocode 3 requirements.

Structural Behaviour of Cold-formed Cut-curved Channel Steel Section Under Compression

Cold-formed steel (CFS) with variety of shape, thickness and steel grade is becoming a popular choice of structure in civil engineering work and building, especially for roof truss system, pallet racking, wall panel and etc. Curved steel element is important in the analysis that be suited by the architectural drawing and structural demand. CFS with a curved section for unique roof truss design is studied. The CFS is curved by using the method of cut-curving in which the CFS section is cut at a certain length and then curved into desired profile. The experiment for determining the mechanical behaviour of the section is by using the compression strength of the column. The height of column is fixed at 600mm but the method for strengthening the cut-curving is varied. There are four types of cut-curving with a variation of strengthening method. The method for strengthening the cut-curved section is by using welding, plate and self-drilling screw. From the compression strength experiment, the cut-curved with full weld and plate is recorded, 21.26% less than the normal straight column.

Applications and Analysis of the Composite wall on Construction in Heilongjiang Province

Applications and Analysis of the Composite wall on Construction in Heilongjiang Province

Экспериментально-теоретические исследования стальных ферм покрытия легкоатлетического манежа в г. Тюмени

Экспериментально-теоретические исследования стальных ферм покрытия легкоатлетического манежа в г. Тюмени

Research on the Seismic Performance of Brick-Concrete Structural Buildings in Indonesian Rural Areas

By investigating on rural housing construction in Djetis county, a region of Java Island Banjul, Indonesia, modeling according to their different weight of roofs and other factories, and combining with 3D seismic wave that was gotten by American EL Centro-seismic wave amplitude modulation to analyze by the finite element, it is shown that the larger quality of roof and the greater the displacement of itself each part, the bigger influence of structure and the easier causes damage. Maximal displacement produced by out-of-plane is larger than maximal displacement produced by in the plane, so the out-of-plain damage is the main cause of structure damage. In addition, based on the finite element analysis, precaution against earthquake measures of limiting to widen the top roof truss girder cross section and setting continuous wall between coupling beam are presented.

Fractal-Based Generative Design of Structural Trusses Using Iterated Function System

The purpose of this study is to apply the notion of fractal geometry in designing structural roof trusses. Fractal geometry, commonly characterized by the features of recursive self-similarity, is considered as a rule-based geometric system that can be generated by using the process of the Iterated Function System (IFS). Lattice configurations of conventional trusses generally show some extend of ‘self-similarity’ features that loosely and sometimes closely resemble with the properties of fractal shapes. The typical configurations of these regular trusses are strategically designed to provide adequate strength and stability to the structures for carrying enough vertical and wind loads. This paper, using the Iterated Function System based on Barnsely's contraction mapping as a generative design method, proposes a new family of truss designs that follow the concept of fractal geometry. The Hausdorff dimensions and the Box Counting dimensions are evaluated to measure the fractality and detailness of the lattices of proposed fractal-based trusses. It also briefly investigates their mechanical properties for analyzing their practical feasibility in construction.

Analysis of Damage to the Historic Roof Truss in Terms of Internal Environment

The main threats that endanger the historical roof trusses in our geographical conditions are wood decaying fungi and wood destroying insects. For these threats to occur and spread across the historical roof truss, several criteria have to be fulfilled within the indoor environment. These critical criteria include wood moisture, relative humidity, amount of daylight and airflow. In addition to these monitored parameters and their critical values, we must not forget the impact of local geographical specifications and wider dependencies. This article is focuses on comparison of theoretical knowledge in this area with in-situ measurements of historical roof trusses on several reference buildings – churches and chapels in Southern Moravia. These were chosen due to their long-lasting nature and circumstances of the construction. The influence of specific local conditions (especially indoor environment) on the extent of damage is also examined in addition to general comparison.

Effect of human error on the reliability of roof panel under uplift wind pressure

Post disaster investigations indicate that the roof damage often occur during strong wind events. Human or construction error could be one of the contributing factors for the observed damage. In this study, a survey was carried out at the IRLBH (The Insurance Research Lab for Better Homes) facility (at the University of Western Ontario) to inspect the quality of construction, especially the fasteners used to fasten the plywood roof panels to the roof trusses. Statistics of missing nails which are required for the fastening are obtained. It was suggested that the occurrence of the missing nail could be modeled using binomial process with the occurrence rate of 1.5%. The effect of the missing nail on the statistics of the panel uplift capacity to wind pressure, which are evaluated using the nonlinear finite element techniques by considering the uncertainty in nail withdrawal behavior, is assessed and compared to those without missing nails. Also, the influence of the missing nail on the reliability of roof panel under wind load is investigated. The implication of the results on the codified design is discussed.

Cross Section Optimization of Plane Truss among Different Spans

Cross sectional areas optimization is to be implemented to study the influence of the cross section shape on the optimum truss weight. By the aid of analysis and design engines with advanced finite element analysis that is the steel design software STAAD. Four rolled steel sections (angle, tube, channel, and pipe) which are used in industrial roof trusses are applied for comparison. Many previous studies, use the areas of cross sections as design variables without highlight to the shape of cross section at the start of the process, consequently the result area will be adequate if the designer choose the effective shape than others. Results of this research show that the chosen cross section shape has a significant impact on the optimum truss weight for same geometry of truss type under the same circumstances of loading and supports.

Geometric Analysis of the Truss above the Nave and Presbytery of the Roman-Catholic Church in Village Bela Dulice

The truss above the nave and presbytery was managed to date to the year 1409d and is one of the few well-preserved medieval structures in this region. This truss has a rafter structure with collar tie and lengthwise binding of the Central frame. At the time of the truss creation the geometry had an important significance, as evidenced by its position in the system of education, since it was a part of seven liberal arts. The part of seven liberal arts was Music and Musica Humana (the theory of proportions) as well, based mainly on Pythagorean theory of proportions. In the Middle Ages geometry substituted complicated static calculations by using the mutual geometric and harmonic spatial connections. The result of our research is the geometric analysis with logical dependencies and a description of a process in the truss design, pointing to evaluative relations came out from especially the Pythagorean Geometry. The typical main roof truss was analyzed and a central longitudinal frame truss as well. Our results point to the use of one of musical ratios: harmonic and irrational proportion. On the basis of the mutual interdependence of the transverse links and central geometrical frame stool we can determine the sequence of key points and reciprocal relationships. Key points create important intersections, which determine the location of the various elements and their mutual carpentry joints. The result is the knowledge of a geometric procedure of a static scheme medieval truss dependent on knowledge of harmonies and ratios.

Strengthening Masonry Cross Vaults Damaged by Geometric Instability

Cross vaults can be easily destabilised when their thrusts are not sufficiently contained by the stiffness of their lateral walls or systems of buttresses. A quarter-scale model from the aisles of Holyrood Abbey church in Edinburgh, which collapsed in 1768 due to excessive load from diaphragm walls that substituted the original roof trusses, demonstrated earlier the pattern of cracks that leads to failure under horizontal spread of supports. A recent model of this vault aimed to study the effects of applying Aramid fibre reinforcement against such failure exactly at the critical cracks, compared to other tests that studied arches or vaults under point load, reinforced continuously. The paper presents how the quality of certain areas of the fabric diverted failure from the longitudinal vertex merging with the detachment of the ribs, as originally observed. Moreover, the repair allowed the vault to resist 50% more spread of its supports, and failure occurred ultimately when new cracks formed in parallel to the repaired ones. The tests and repairs validate qualitative observations on crack patterns and failure of real cases and highlight the benefits and limitations when specific repairs are made instead of wholesome application of a reinforcing mesh at the extrados of vaults.

Structural and Economic Viability of 2D/3D Finite Element Analysis of Conical Arched Roof Truss

Arch and conical roof trusses are employed when dealing with large span roof trusses. But a combination of the two geometrical shapes may lead to a better economical sections and a means of dealing with larger spans of roof truss that are not suitable for an arch or conical roof truss. Consequently, this paper examines the structural and economic viability of arched conical roof truss system based on 2D/3D finite element method analysis. Analysis of the results showed that truss members were subjected to higher axial forces in 2D analysis than 3D analysis, which will result to overdesign of the structural members and the attendant high construction cost. There are some variations observed in the axial forces for trusses located at edges of polygon when compared with the trusses located mid-point between two polygonal edges. This observation is quite significant in the sizes of the steel section properties of the members as well as in the fabrication and installation cost.

Low Cost Roof System For Rural Housing

1.1 Near about 5.6% of the total tribal population of India live in “MEWAR” and “VAGGAR” region of Rajasthan state. In this region, lot of tribals are residing in the out-skirts of Banswara, Udaipur, Pratapgarh and Dungarpur districts. They prefer to live in the jungle with the nature and build their huts by using local material and local skill. It is imperative to introduce the innovative technology of the construction of rural cost-effective huts, which is based on the adoption of the local environment and constructed with the house-hold themselves without the need of the modern tools & equipment. If, we analyze the building costs and its break up, it is observed that the main components of the building are foundation, wall, roof, door & window, flooring and finishing etc. The maximum expenditure for rural houses after construction of walls is in roofs which is 25 % of total expenditure. Therefore, to reduce the cost of the roof of the rural houses this study was under-taken. Necessary sustainable cost-effective techniques are developed for supporting system by use of Bamboo roof trusses and Bamboo spaced column for costeffective rural huts. The average cost break-up of rural hut are shown as below A rural house is a structure providing the suitable place for protecting rural people from heat, cold, rain and wild animals. It can be built with different types of roof covering materials like thatch, tiles, slate, galvanized iron sheets and corrugated asbestos sheets over a supporting structure at present it is a baulk or trunk of a tree and the mud walls. In place of the high cost of supporting structure, bamboo trusses are introduced as the cost-effective system for supporting the roof covering

The effect of roof systems on seismic performance of reinforced concrete frame-bent main building of large-scale thermal power plant

The roof systems of turbine hall in large-scale thermal power plant are often simulated by approximate rigid beam model. Wenchuan earthquake again revealed the frequent destruction of these roof systems. In this study, three kinds of general roof systems as space grid, trapezoid steel roof truss and reinforced concrete (RC) mansard roof truss were considered. Also, the numerical model of RC frame-bent main building in large-scale thermal power plant was established. Seismic performance of main building was compared with approximate rigid beam model, and the damage mechanism of roof systems was also investigated. The results indicate that the response calculation of frame part by rigid beam model is feasible, and roof systems give most contribution to the response of bent part. After considering roof systems, overall collaborative performance is enhanced, but bent part is still unable to become a second defence part after shear walls fail. The torsional irregularity of roof systems is very serious, and more attentions should be paid to the bearing shear failure of space grid and components strength failure of RC roof systems. Copyright © 2014 John Wiley & Sons, Ltd.

The Effect of Dust Overload on Security of Single Layer Steel Structural Workshop

Based on the investigation of a single layer steel structure industry workshop in Baoshan Steel Incorporated Company, the effect of dust overload on the security of single layer steel structural workshop is analyzed, which is the basis of maintenance and monitor of the building. The results show that the dust-load overload 16%, the ratio of resistance-load of roof truss, bracket and framework column separately reduce 4%,4%,0.5%. If the dust-load overload 100%, the ratio of resistance-load of roof truss, bracket and framework column separately reduce 20%, 20%,1%.

Damage avoidance design for buildings

Seismic Damage Avoidance Design (DAD) principle that incorporates rocking wall with armoured steel wall to foundation seat details are presented for a class of warehouse type building. The walls consist of a mix of seismic wall panels and non-seismic infill cladding panels. The seismic wall panels are used to seat the rafters. Lateral loads are transmitted via diaphragm action through a roof truss. This design procedure involves seven steps. A key step of this procedure is the evaluation of total effective damping which includes intrinsic, hysteretic and radiation damping arising from rocking of the wall panels. Damping reduction factors for short, medium and long periods for the seismic design demand spectrum are also considered. The design is confirmed and validated using nonlinear time-history analysis under various earthquake ground motions.

Design, testing and implementation of a Cu-SMA-based device for improving the thermal behavior of steel tie-rods

Steel cables, tendons and tie-rods are the key components of many structures including masonry arches and vaults, timber roof trusses and several post-tensioned structures. In this paper, a device prototype based on the superelastic properties of Cu-based Shape Memory Alloys (SMAs), is proposed to enhance the thermal behavior of such structural elements. The thermal behavior of steel tie-rods with and without SMA is evaluated through comprehensive experimental tests in thermal room. During the tests, different temperature–time histories are considered, with air temperature varied between −10°C and 40°C. The results of the experimental tests confirm the great effectiveness of the proposed SMA device, with reductions of force changes due to air temperature variations of the order of 80–90%, compared to steel tie-rods without SMA. In the paper, the main structural components and basic functioning principles of a SMA-based device prototype for masonry arches and vaults are presented and aspects related to its implementation in practice are discussed in detail.