Main Structural Members Research Articles

FIRE RESISTANCE PERFORMANCE OF CELLULAR STEEL BEAM (CSB) AT ELEVATED TEMPERATURES

Cellular steel beam (CSB) is getting more and more popular to be used as the main structural member for steel building structure in the United Kingdom (UK). Despite quite costly to erect and assemble a steel structure member compared to concrete, it has several advantages in terms of lightweight material, higher strength, easy to assemble and aesthetic value. Even though the use of CSB is quite significantly positive, the negative side also needs to be addressed. Any steel structures are prone to fire exposure scenario. The strength of CSB will be significantly decreased when exposed to elevated temperature due to fire. Large deformation from experimental procedure will be clearly seen after the time-temperature curve reach critical stage. Vierendeel bending mechanism and web-post buckling are some of the drawbacks of the CSB at elevated temperature. In this paper, general purpose ABAQUS Finite Element (Version 6.14) on large deformation of protected and unprotected CSB at elevated temperature is proposed. Performance based approach is introduced to validate the numerical analysis with the experimental results from the available Compendium of UK Standard Fire Test Data produced by British Steel Corporation Research Services, Swinden Laboratories, UK.

Seismic response of steel braced frames equipped with shape memory alloy-based hybrid devices

This paper highlights the role of innovative vibration control system based on two promising properties in a parallel configuration. Hybrid device consists of two main components; recentering wires of shape memory alloy (SMA) and steel pipe section as an energy dissipater element. This approach concentrates damage in the steel pipe and prevents the main structural members from yielding. By regulation of the main adjustable design parameter, an optimum performance of the device is obtained. The effectiveness of the device in passive control of structures is evaluated through nonlinear time history analyses of a five-story steel frame with and without the hybrid device. Comparing the results proves that the hybrid device has a considerable potential to mitigate the residual drift ratio, peak absolute acceleration and peak interstory drift of the structure.

外圧を受けるリング補強円筒殻の胴板座屈強度および補強リングの横倒れ座屈強度に関する研究

Ring stiffened cylinder is generally used as main structural members of offshore and submergible structures. In designing of such structures, it is very important to estimate the buckling strength of ring stiffened cylinder under external pressure accurately. The buckling mode of ring stiffened cylinder under external pressure can be divided into the following four modes. The first is the general buckling mode which occurs over the entire length of the cylinder involving ring stiffeners. The second is the shell buckling mode which is the buckling of cylindrical shell between the ring stiffeners. The third is the frame tripping mode of ring stiffener. The fourth is the local buckling mode of ring stiffener’s web or face. The purpose of this research is to propose the simplified formula for predicting the elastic shell buckling strength included the influence of stress ratio of shell and ring stiffener, and to propose the simplified formula for predicting the elastic ring frame tripping strength combined the proposed formula of the elastic shell buckling strength. The elastic shell buckling strength and the elastic ring frame tripping strength predicted by these simplified formulas are compared with the result of finite element analysis by changing various parameters, such as the scantling of ring stiffener and shell thickness. From the comparison of these results, accuracy of these simplified formulas is examined.

A parametric study on the use of passive fire protection in FPSO topside module

Fire is a continuous threat to FPSO topside modules as large amounts of oil and gas are passing through the modules. As a conventional measure to mitigate structural failure under fire, passive fire protection (PFP) coatings are widely used on main structural members. However, an excessive use of PFP coatings can cause considerable cost for material purchase, installation, inspection and maintenance. Long installation time can be a risk since the work should be done nearly at the last fabrication stage. Thus, the minimal use of PFP can be beneficial to the reduction of construction cost and the avoidance of schedule delay. This paper presents a few case studies on how different applications of PFP have influence on collapse time of a FPSO module structure. A series of heat analysis and thermal elasto-plastic FE analysis are performed for different PFP coatings and the resultant collapse time and the amount of PFP coatings are compared with each other.

강봉댐퍼로 보강한 기존 저층 철근콘크리트 필로티 건물의 내진성능

In this study, shaking table test was carried out to evaluate the seismic behavior and performance of low-rise reinforced concrete (RC) piloti structures with and without retrofit. The specimens were designed considering the characteristics of existing building with pilotis such as natural period, distribution factor of strength and stiffness between columns and core wall on the first soft story. The test for the non-retrofit specimen showed that damage was concentrated on the stiffer member on the same floor as the core wall failed by shear fracture whereas columns experienced slight flexural cracks. Considering the failure mode of the non-retrofit specimen, the retrofit method using steel rod damper was presented for improving the seismic performance of piloti structures. The results of the test for retrofit specimen revealed that the retrofit method was effective for controlling the damage as the main RC structural members were not destroyed and most of input energy was dissipated by hysteretic behavior of the damper.

Enlargement of Atocha Railway Station (Stage I)

Stage I of the enlargement of Atocha Railway Station aimed primarily to adapt the facility to a new operating model, raising the station's capacity essentially by separating arriving and departing passenger traffic.This article describes the project background, scope and justification, as well as the main structural members and most significant works involved in the enlargement, distinguishing between construction in platforms and tracks and existing facility restructuring.In light of the complex geometry of the new roofs over Atocha Station, computational fluid dynamics (CFD) techniques were deployed to verify the pressure coefficients initially adopted for the new platform canopies by extrapolation from the existing legislation. The structural engineering involved is addressed.Lastly, logistics and planning are discussed, with an account of all the possible scenarios and the challenge of performing many activities simultaneously on a tight schedule in limited quarters (power outages, track beds, high voltage works,…). The exceptional constraints inherent in the need to maintain high-speed train (“AVE”) service during the works intensified the overall complexity.

Ampliación del Complejo Ferroviario de Atocha (Fase I)

Stage I of the enlargement of Atocha Railway Station aimed primarily to adapt the facility to a new operating model, raising the station's capacity essentially by separating arriving and departing passenger traffic.This article describes the project background, scope and justification, as well as the main structural members and most significant works involved in the enlargement, distinguishing between construction in platforms and tracks and existing facility restructuring.In light of the complex geometry of the new roofs over Atocha Station, computational fluid dynamics (CFD) techniques were deployed to verify the pressure coefficients initially adopted for the new platform canopies by extrapolation from the existing legislation. The structural engineering involved is addressed.Lastly, logistics and planning are discussed, with an account of all the possible scenarios and the challenge of performing many activities simultaneously on a tight schedule in limited quarters (power outages, track beds, high voltage works…). The exceptional constraints inherent in the need to maintain high-speed train («AVE») service during the works intensified the overall complexity.

Behavior of a steel coupled beam moment frame based on nonlinear analyses

A steel coupled beam moment frame (CBMF) is an innovative seismic resisting moment resisting frame that is composed of coupled beams and steel columns. A coupled beam features a pair of steel beams, post-tensioning elements, and energy dissipation devices. Coupled beams can be fabricated in shop and pin-connected to columns on site, facilitating the field construction. Energy dissipation is provided by a special energy dissipation device, not by damage to the main structural members or to the energy dissipation device itself. Rotations at beam–column joints are the result of a relative slide mechanism of the coupled beams, not the result of beam plastic hinges. During unloading, the force in the PT elements eliminates coupled beam relative slide as well as rotations at beam–column joints, offering the potential of minimal residual rotations to coupled beam–column connections. This paper presents conceptual details, conceptual behavior, and design considerations for CBMFs. For behavior study, a prototype building using CBMFs as the lateral resisting frames was designed. A nonlinear analysis model for the prototype building was created. Static pushover and cyclic push analyses were conducted to assess the concepts. Dynamic time history analyses using a 44-ground motion record set were performed to study the post-earthquake residual story drift and residual connection rotation response of the prototype CBMF building. Analysis results showed that the global behavior and connection response of the prototype CBMF supported the conceptual behavior and design considerations, and that post-earthquake story drifts and connection rotations of the prototype CBMF building are ignorably small.

Development of One-hour Fire-resistive Building Materials Made of Combustible Japanese Cedar Using Laser Incising

Conventional glued-laminated timber (glulam) was not permitted any more to be applied to a wooden building in the fire preventive district since the amendments of the Building Standard Law in 2000. The Japanese Government set the self-sufficiency rate of the domestic wood supply at 50% within ten years in 2011 and enacted the new legislation to promote wooden structures and wooden interior decorations in public buildings as long as possible. Therefore, it is strongly desired to develop fireproof structural materials usable in urban area to achieve goals. Therefore, one-hour fireproof glued-laminated timber (glulam) and cross laminated timber (CLT) were developed made of Japanese cedar (Cryptomeria japonica D. Don) which is the major species in Japan and combustible by incision to fire-die-out part of lamina with CO2 laser. The structure in cross-section of the glulam consists of three zones, namely, load-bearing part (untreated glulam), fire-die-out part impregnated fire-retardant chemicals and surface part (untreated lamina). An one-hour fire-resistive CLT was also developed using the same concept as the glulam and its performance was confirmed by the fire-resistance test. The first wooden building whose main structural members were made of the fireproof glulam marketed as FR wood® was also introduced briefly.

Energy dissipation system for earthquake protection of cable-stayed bridge towers

For economical earthquake resistant design of cable-stayed bridge tower, the use of energy dissipation systems for the earthquake protection of steel structures represents an alternative seismic design method where the tower structure could be constructed to dissipate a large amount of earthquake input energy through inelastic deformations in certain positions, which could be easily retrofitted after damage. The design of energy dissipation systems for bridges could be achieved as the result of two conflicting requirements: no damage under serviceability limit state load condition and maximum dissipation under ultimate limit state load condition. A new concept for cable-stayed bridge tower seismic design that incorporates sacrificial link scheme of low yield point steel horizontal beam is introduced to enable the tower frame structure to remain elastic under large seismic excitation. A nonlinear dynamic analysis for the tower model with the proposed energy dissipation systems is carried out and compared to the response obtained for the tower with its original configuration. The improvement in seismic performance of the tower with supplemental passive energy dissipation system has been measured in terms of the reduction achieved in different response quantities. Obtained results show that the proposed energy dissipation system of low yield point steel seismic link could strongly enhance the seismic performance of the tower structure where the tower and the overall bridge demands are significantly reduced. Low yield point steel seismic link effectively reduces the damage of main structural members under earthquake loading as seismic link yield level decreases due their exceptional behavior as well as its ability to undergo early plastic deformations achieving the concentration of inelastic deformation at tower horizontal beam.

An efficient genetic algorithm for the design optimization of cold-formed steel portal frame buildings

The design optimization of a cold-formed steel portal frame building is considered in this paper. The proposed genetic algorithm (GA) optimizer considers both topology (i.e., frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables. Previous GAs in the literature were characterized by poor convergence, including slow progress, that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented that is shown to be an effective means of enhancing the dissimilarity of the solutions in each generation of the GA. Thus, population diversity is maintained and premature convergence is reduced significantly. Through benchmark examples, it is shown that the efficient GA proposed generates optimal solutions more consistently. A parametric study was carried out, and the results included. They show significant variation in the optimal topology in terms of pitch and frame spacing for a range of typical column heights. They also show that the optimized design achieved large savings based on the cost of the main structural elements; the inclusion of knee braces at the eaves yield further savings in cost, that are significant.

Contribution of the fill to the static behaviour of arched masonry structures: theoretical formulation

In the paper, one presents the theoretical set-up of an original formulation aimed at accounting for the contribution of the fill to the structural strength of masonry vaults and arches and at providing an evaluation about its skill of cooperating to stress absorption with the main vaulted resisting structure. Usually the action of components ordinarily regarded as non-structural members is often neglected in static analyses. Actually, it is a common practice to assume a number of elements of vaulted or arched constructions, such as the fill and the buttress, as completely unable to exert any structural action, rather than trying to evaluate their contribution; therefore, those are usually assumed to be a dead weight, unable to contribute to the bearing capacity of the vault. Starting from the consideration that the fill is somehow subject to some pre-compression because of the permanent load, an approach is proposed where the fill is considered to be able to provide a partial absorption of the variable loads with a reduced load transmission onto the main structural members. The procedure leads to more realistic evaluations about the safety assessment of vaulted structures, which are in major agreement with their real behaviour.

Tests of damaged members of facade scaffolding bearing frames

The preparation and execution of laboratory tests for analysis of influence of operational damage in the main structural member of facade scaffolding bearing frame on the frame capacity are presented in this paper. Virtually unavoidable presence of defects demands reduction of the material strength in comparison to the theoretical one. Numerical analysis has been preceded by author’s own laboratory tests which allow to description in detail the behavior of scaffolding member.

Failure analysis of Upright & Base for Shelving Rack

Shelving system is used for the display & storage of Books, Pharmacy products, FMCG goods, electronic goods, canned goods, hardware etc. CAEM is shelving Engineering for the Retail Sector which manufactures modular metal shelving systems for the shop fitting industry. The main structural members of steel storage racks are uprights & Bases. CAEM India imports upright & bases from CAEM Italy for shelving racks. In this work, the commercial software, ANSYS, is used for material and geometric nonlinear analysis of the upright & base and the results are compared with analytical data obtained & providing a suitable design for the same.

플레이트형 에너지 흡수장치를 가지는 기둥-보 접합부에 관한 연구

Recently, there is a growing interest on sustainable connection system that makes it possible to reuse of main structural members by concentrating most of the damage in the frame caused by strong horizontal force, such as earthquake, to damper. In this study proposed a new type of damage-controlled connection system applying these concepts and analysed the major structural performance of the proposed system through the full-scale cyclic loading test and nonlinear finite element analyses. According to the result, it derived the optimal damper/beam strength ratio that minimize the damage of main members and satisfy at least the fully plastic moment of the beam. And it was to verify the possibility of applying as seismic connection details.

Structural assessment of a modern heritage building

A structural assessment study on “Palazzo del Lavoro” in Turin, a masterpiece by Pier Luigi Nervi, was carried out within a National Research Project dedicated to the analysis of modern heritage architecture in Italy. Based on the original design documentation collected through records, a complete finite element model of the building was generated. The study included detailed models of the main structural members, represented by monumental reinforced concrete columns, a mushroom-type steel roof and reinforced concrete ribbed gallery slabs, and the main non-structural systems, constituted by continuous gallery-to-roof glazed façades. The results of the linear and non-linear analyses developed by these models, aimed at fully understanding the original design concept of the various members, as well as at evaluating their current static and seismic safety conditions, are reported in this paper. The non-linear computations include a buckling analysis of the slender steel beams constituting the roof, and an “integral” seismic pushover analysis of the monumental columns. The results of the analyses highlight safe conditions and good performance objectives in general, but for some important exceptions. Indeed, the roof beams failed to pass the verifications on global and local panel flexural–torsional buckling, and some cantilever beams of the gallery floors showed poor shear resistance. Retrofit hypotheses are also formulated for these elements, so as to help the entire structure to comply with the requirements of the new Italian Technical Standards.

Non Linear Static Analysis Of Knee Bracing In Steel Frame Structures

In order to dissipate input earthquake energy in the moment resisting frame (MRF) and concentrically braced frame (CBF), inelastic deformation in main structural members, requires high expense to repair or replace the damaged structural parts. The proposed knee braced frame (KBF) is a steel frame structure in which the diagonal brace provide most of the lateral stiffness and the knee anchor that is a secondary member, provides ductility through flexural yielding. In this paper the results and analysis on affects of knee bracings on steel structure is provided by considering non linear static pushover analysis of knee braced framed structure . various parameters such as ductility , base shear , displacement is studied by analysis of moment resisting frame and other types of knee braced frames on Sap2000. finite element modelling software.

Static Analysis of Loading Properties of Small-Size Single-Pylon Cable-Stayed Bridge

This paper introduces the design of a small-size single-pylon cable-stayed bridge to be built in Xingtai city, China. The main structural members of this bridge including box-girder, stayed cables and pylon were selected to meet the requirement of bearing properties and artistic display. The numerical model for analyzing the static properties of the bridge structure was made by the design software MIDAS/Civil. The distribution and ultimate value of internal forces, stress and displacement of these main members are summarized, which provide the basis for calculating the reinforcement and prestressed strands of the bridge.

Numerical and experimental investigation on the temperature distribution of steel tubes under solar radiation

The temperature on steel structures is larger than the ambient air temperature under solar radiation and the temperature distribution on the affected structure is non-uniform and complicated. The steel tube, as a main structural member, has been investigated through experiment and numerical analysis. In this study, the temperature distribution on a properly designed steel tube under solar radiation is measured. A finite element transient thermal analysis method is presented and verified by the experimental results and a series of parametric studies are carried out to investigate the influence of various geometric properties and orientation on the temperature distribution. Furthermore, a simplified approach is proposed to predict the temperature distribution of steel tube. Based on both the experimental and the numerical results, it is concluded that the solar radiation has a significant effect on the temperature distribution of steel tubes. Under the solar radiation, the temperature of steel tubes is about <TEX>$20.6^{\circ}C$</TEX> higher than the ambient air temperature. The temperature distribution of steel tubes is sensitive to the steel solar radiation absorption, steel tube diameter and orientation, but insensitive to the solar radiation reflectance and thickness of steel tube.

지붕 구조 내화성능 분류체계 설정을 위한 실험적 연구

건축물은 화재시 그 피해를 최소화하기 위해 건축물 주요 구조부를 일정 수준의 내화구조로 시공하고 있으며, 이러한 주요 구조부 중 하나인 지붕의 경우 현재 지붕틀에 대하여만 내화성능을 정부에서 확인하여 인정한 법정내화구조로 규정하고 있다. 또한 이경우도 규정된 후 상당한 시일이 경과되어 최근의 건축재료 및 공법의 기술발전을 적절히 수용하지 못하고 있는 실정이다. 이에 따라 현재 주요구조부와 법정내화구조로 규정된 지붕구조에 대한 성능확인 등을 통한 내화성능을 재설정할 필요가 있으며. 이에 본 연구에서는 국내의 주요구조부와 법정내화구조로 규정된 지붕 구조를 대상으로 내화성능을 평가하여 내화구조를 세분화한 기초자료를 제시하였다. To minimize the damages under fire conditions in buildings, the main structural members of buildings shall be fire-resistance-rated structural members. For the roof which is one of the main structural members, the relevant authority only specifies the prescriptive fire-resistance-rated roof frames whose fire resistance performance has been checked by the relevant authority in building laws at present. But, these prescriptive fire-resistance-rated roof frames don't properly reflect the recent construction materials and the technical development of methods of construction as a long time has passed. Consequently, it is needed to reset the fire resistance performance through the performance evaluation for the roof constructions specified as the present main structural member and the prescriptive fire-resistance-rated construction. This study was intended to give the fundamental materials that prescriptive fire-resistance-rated roofs are departmentalized as each structure by evaluating the fire resistance performance of the roof construction specified as the present main structural member and the prescriptive fire-resistance-rated construction.