Floor Beams Research Articles

Numerical study on the flexural behaviour of slim-floor beams with hollow core slabs at elevated temperature

Slim-floor beams are a novel typology of steel beams where the steel profile is fully embedded within the concrete floor depth. While the use of this system is increasing fast in the construction practice, the available investigations on its fire performance are still scarce. This paper focuses on analysing the fire behaviour of slim-floor beams combined with hollow core slabs as flooring system. Two configurations are studied, namely Integrated Floor Beam (IFB) and Shallow Floor Beam (SFB). A finite element model is developed and validated by comparison with experimental results available in the literature as well as with thermal tests carried out by the authors. Subsequently, parametric studies are conducted with the aim of providing practical design recommendations. The influence of the composite beam configuration, concrete type, longitudinal reinforcement and steel plate thickness is studied. The conclusions drawn in this paper suggest that the SFB configuration may provide a significant enhancement in terms of fire resistance compared to IFB, provided that the appropriate combination of the parameters studied is used.

Ultimate strength capacity of composite self-compacting castellated steel beams

Castellated steel profile sections can be used in order to increase the flexure strength of composite concrete-steel beams for building large spans. Castellated beams are fabricated by cutting I-section steel girders in a special manner before welding to produce an opening throughout the web. The depth of the new section is enhanced by a specific percentage, which increases the performance of the beam against bending. Castellated beams can be used compositely in long span floors where floor beam heights are kept to a minimum by passing services through the web-openings. This paper will focus on the composite behaviour of specimens in two types of concrete with different strengths. The ultimate strength for these types of structures with different degrees of castellation will be considered. The study consisted of two parts: the first part tested six specimens using push out test specimens to understand the real behaviour of their shear connectors. The second part tested eight specimens under a third point static load. Three of the push out test specimens were of normal concrete, and the others were self-compacting concrete.Four of the composite beam specimens were normal concrete slabs, while the other four specimens were made from self-compacting concrete. The experimental programme also included fabrication of I-section steel beams with different castellation degrees of 0%, 25%, 33.8%, and 50%. The effects of concrete type and degree of were thus studied. It was found that the maximum load capacity was significantly affected by these parameters such that it was increased with both the increase of compressive strength of the concrete and the degree of castellation. The push out test showed that the slip behaviour was linear below 70 to 80% of the ultimate load capacity. At this linear stage, the amount of slip is very low and rarely exceeds 0.5 mm.

Response of Asymmetric Slim Floor Beams in Parametric-Fires

State-of-the-art slim floor systems are a newest addition to the composite construction industry and several types are currently being used for building and construction purposes. Asymmetric slim floor beams are a type of slim floor systems which consist of a rolled section with a larger bottom flange. The larger bottom flange induces asymmetry and offers an efficient use of the material strength as a composite beam. It also offers a larger area to support the steel decking and pre-cast slab units during the construction of floor. Experimental and analytical investigations on response of asymmetric slim floor beams have shown that these beams offer a higher fire resistance in comparison to the conventional composite systems with down-stand steel beams. Previous investigations on these beams have been conducted in standard fire exposure conditions, hence, their response to natural fire scenarios still deems further examination. This study addresses response of asymmetric slim floor beams in natural fire exposure conditions. For this purpose, finite element models developed and verified by the authors are employed to study the thermal and structural response of slim floor beams in fast and slow parametric-fire exposures. Results obtained show that the asymmetric slim floor beams behave differently in parametric-fires in comparison to that in standard fire exposure conditions. Asymmetric slim floor beams continued to support the loads for the whole duration of parametric fires without undergoing excessive deflections and offering a better fire resistance. Unlike in case of the standard fire where the temperatures keep on increasing throughout the duration, temperatures on the slim floor beams decrease after reaching a maximum point in parametric-fires. It was found that for fast parametric-fires, the thermal gradient across the section is more severe as compared to that for the slow parametric-fires at earlier stages of fire exposure. In case of the fast parametric-fires, the rise and fall of temperatures on the slim floor beams are rapid while in case of the slow parametric-fire, these variations in temperatures are subtle. It was observed that the structural response of slim floor beams in standard and parametric fires depends on the average temperature across the steel section. Deflections predicted for the beams were found to be directly related to these average temperatures. Outcomes of this study will benefit in understanding the response of asymmetric slim floor beams in natural fire conditions and will aid to develop simple fire design methods for future use.

Cover Picture: Steel Construction 4/2018

AbstractTorre Diamante in the heart of Milano is with 130 m the tallest steel building in Italy. The use of high strength steel sections enables a low total weight, advantageous costs, less transport, slender columns and a preferred raft foundation. With long span composite floor beams flexible column‐free offices and integrated building services can be realised. For the LEED certification the recycling‐material steel played a major role. (Foto: Bernhard Hauke)

Automated, strain-based, output-only bridge damage detection

This paper presents a framework for automated damage detection using a continuous stream of structural health monitoring data. The study utilized measured strains from an optimized sensor set deployed on a double track, steel, railway, truss bridge. Stringer–floor beam connection deterioration, a common deficiency, was the focus of this study; however, the proposed methodology could be used to assess the condition of a wide range of structural elements and details. The framework utilized Proper Orthogonal Modes (POMs) as damage features and Artificial Neural Networks (ANNs) as an automated approach to infer damage location and intensity from the POMs. POM variations, which are traditionally input (load) dependent, were ultimately utilized as damage indicators. Input variability necessitated implementing ANNs to help decouple POM changes due to load variations from those caused by deficiencies, changes that would render the proposed framework input independent, a significant advancement. To develop an automated and efficient output-only damage detection framework, data cleansing and preparation were conducted prior to ANN training. Damage “scenarios” were artificially introduced into select output (strain) datasets recorded while monitoring train passes across the selected bridge. This information, in turn, was used to train ANNs using MATLABs Neural Net Toolbox. Trained ANNs were tested against monitored loading events and artificial damage scenarios. Applicability of the proposed, output-only framework was investigated via studies of the bridge under operational conditions. To account for the effects of potential deficiencies at the stringer–floor beam connections, measured signal amplitudes were artificially decreased at select locations. It was concluded that the proposed framework could successfully detect artificial deficiencies imposed on measured signals under operational conditions.

Effect of air-gap on response of fabricated slim floor beams in fire

PurposeThe purpose of this study is to investigate the effect of the airgap on thermal behaviour and structural response of fabricated slim floor beams (FSFBs) in fire.Design/methodology/approachA detailed analytical model is established and validated by replicating the response of FSFBs. The validated finite element modelling method is then used to perform sensitivity analysis. First, the influence of the airgap presence is analysed, and later, the effect of the airgap size on thermal behaviour and structural response of FSFBs at elevated temperatures is investigated.FindingsResults from the study demonstrate that the presence of the airgap has a considerable influence on their thermal behaviour and structural response of FSFBs. The size of the airgap, however, has no significant influence on their thermal and structural response in fire.Originality/valueNo investigations, experimental or analytical, are available in literature addressing the effect of airgap on the structural response of FSFBs in fire. The presence of airgap is helpful and beneficial; hence, the findings of this research can be used to develop designs for structural members with airgap as an efficient and inexpensive way to improve their response in fire.

Service and Ultimate Behaviour of Slim Floor Beams: An Experimental Study

Slim floor systems represent an economical and competitive solution for building applications that combine the advantages of concrete floors, prefabricated steel sections and a shallow depth. The distinctive feature of this form of construction relies on the fact that the lower steel flange is wider than the top flange to provide a continuous support along the beam length for the slab formwork. The latter is usually specified in the form of either profiled sheeting or cellular slabs. In this structural typology, the steel section is embedded within the thickness of the slab.This paper presents an experimental study aimed at evaluating the service behaviour of slim floor beams induced by the time-dependent behaviour of the concrete and at establishing the possible influence of creep effects on their ultimate response. For this purpose, two slim floor samples were prepared in a simply-supported configuration. Their long-term deflections and deformations were monitored over time for about ten months, after which the specimens were tested to failure. The specimens possessed identical concrete and steel geometries. The shear connection was provided by transverse steel reinforcing bars installed within regularly spaced holes incorporated in the steel web. The samples were cast unpropped so that the self-weight of the wet concrete was carried by the steel member. The only difference between the two specimens consisted in the loading history specified over time. In particular, one slim floor sample was kept unloaded for the entire duration of the test to monitor the influence of shrinkage effects while the second specimen was subjected to a sustained load to evaluate the effects of both creep and shrinkage. The experimental data reported in this study provides insight into their long-term and ultimate response, and valuable benchmarking data for the calibration of numerical models and design procedures related to the serviceability and ultimate limit states of slim floor systems.

Re-examination of steel frame office buildings in preventing collapse when subject to intense fires

The purpose of the paper is to investigate the extent to which present-day design of steel framed buildings is susceptible to total collapse when subjected to extreme fire events. We select a 50 storey structure in which 2 and 4 adjacent storeys located at different above-ground heights are, in separate scenarios engulfed in raging fires. A total of 8 scenarios are analyzed, employing Newtonian mechanics and realistic energy dissipating properties of H-shaped columns and normal concrete floor slabs possessing secondary (shrinkage and temperature) reinforcement alone. While the present Canadian building code is the basis for our column designs, other standards provide very similar specifications. Although fire proofing is required in virtually all high rise building construction, we are excluding such materials in order to simplify the analyses, but clearly do not advocate its omission – quite the opposite in fact. As well, attributes such as floor beams, partitions and furnishings of every description, all of which would in practice participate in absorbing the kinetic energy of a crush-down upper block are excluded. Despite such a vast array of conservative assumptions, it is shown that partial collapse may occur during crush-down, however, in no case will total collapse be the consequence. These results should provide some comfort to code writers that their requirements should indeed prevent the most catastrophic of failures due to fires.

Weight optimization of composite cellular beam based on the differential evolution algorithm

In this study, the differential evolution algorithm is used for solving the optimum design problem of composite cellular beams. The design variables are hot rolled profile from which the cellular beam will be produced as well as opening size and its spacing. The objective function is the minimum weight of cellular beam while the design constraints include satisfying the ultimate limit states, the serviceability limit states and the geometric limitations. The design method adopted in this study is based on EN 1994-1-1. Furthermore, a parametric study is conducted to evaluate the influence of beams spacing to the weight of floor beam system. As a result, an optimal spacing of composite cellular beams is proposed.
 Keywords: composite beam; cellular beam; web opening; steel beam optimization; differential evolution.

Robust and Reliability-Based Design Optimization of a Composite Floor Beam

This study investigates the advantages and disadvantages of using probabilistic optimization methods in aircraft structural design. The necessity to achieve a design insensitive to system's variations (robust) and less likely to fail (reliable) is addressed, in order to reduce costs and risk of accidents. Because of the complex nature of composite structures, the need of surrogate models to predict structural responses arises. In order to build a meta-model, Design of Experiments (DOE) methods are used to determine the location of sampling points in the design space. Monte Carlo Simulations (MCS), creating random samples, are used to propagate uncertainties from the surrogate model inputs to variations in model outputs. Different optimization algorithms and surrogate models are compared, in order to speed up the optimization process and reduce modelling errors. The deterministic design resulted in a design which is neither robust nor reliable. Stochastic approaches accounting for uncertainties, on the other hand, resulted in enhanced robustness (Robust Design), enhanced reliability (Reliable Design) or a combination of both (Robust and Reliable Design).

Perencanaan Proyek Pembangunan Office Centre Anfen Jalan Pringgading – Semarang

AnFen Office Center building is used for office rentals, expected to be a place of business opportunity. The AnFen Office Center building includes office buildings that are used for professional business, administrative or commercial operations. This building has 5 floors with an area of ± 2023,44 m 2 . The roof of the building is planned using a concrete plate. The shear wall is planned to use the type of l frame wall from the ground floor to the 5th floor which aims to withstand the lateral force caused by the earthquake. Calculation of structures in AnFen Office Center building using SNI 03-1726-2012 for earthquake resistant building count and SNI 03-2847-2002 for construction calculation. Lower structure planning includes pile foundation, pile cap, tie beam, while the top structure includes floor plate, column, beam, roof plate, ladder and shear wall. In the calculation of moments and reactions that work on this building using software SAP 2000 Version 17.2.0. The result of design calculation of floor plate plate with thickness of 20 cm for ground floor plate and 12 cm for floor plate plate 1-5 up to roof plate. Design of beam design with dimensions B1 = 450 × 700, B2 = 300× 550. Design planning column with design K1 = 800 x 800. Design planning pile foundation diameter 60 cm at a depth of 12 m.

ADAPTATION AND CONSERVATION OF THE SRI MANGANTI HALL AT YOGYAKARTA’S KERATON PALACE COMPLEX

Abstract - Yogyakarta’s Keraton palace forms part of the Special Region of Yogyakarta (DIY) that has architectural values of high standing. Apart from this, the hall called Sri Manganti takes specific pride of place in this palace. The purpose of this research project is to reveal these architectural aspects through establishing their cultural significance, meaningful architectural elements and the conservational measures applied to this particular hall. The theories employed for this piece of research include the Capon theory, the Orbasli theory, the Feilden theory, the Forsythe theory, and finally the Javanese Tradition Architectural theory. The methods used consist of the descriptive and the qualitative method along with the architectural approach to the matter of the building’s form and function, and the local conservation of the various cultural meanings. The cultural significance of the Sri Manganti hall lies in the application of the Javanese architectural concept of Joglo Mangkurat (referring to the roof’s steep upper section) along with the hanging structure known as Lambung Gantung, aesthetic appreciation of Javanese culture and tradition and exhibition and performance of Javanese art. The architectural and aesthetic values can be discerned in its architectural components consisting of the fundament, floor, poles/pillars, supporting and upper wooden beams called ander & molo, ceiling, roof, various decorations and the general lay-out. A valuable building like this has apparently suffered from loss of quality in the components of its construction. This decline in quality could have been caused by the impact of the tropical climate, faulty maintenance and certain questionable human measures taken. On the other hand, it turns out that the change of function into an exhibition venue for art has actually brought added value in terms of the building’s usefulness.This building falls under the essential buildings that make up the Keraton palace, so its general condition needs to be properly maintained, both with the measures taken to adapt and conserve it for the future.Keywords: architectural value, aesthetic value, conservation, adaptation, preservation

Stiffness Effects of Structural Elements on the Seismic Response of RC High-Rise Buildings

Abstract The stiffness of structural elements (columns, beams, and slabs) significantly contributes to the overall stiffness of reinforced concrete (RC) high-rise buildings (H.R.B.s) subjected to earthquake. In order to investigate what percentage each type of element contributes to the overall performance of an H.R.B. under seismic load, the stiffness of each type of element is reduced by 10% to 90%. A time history analysis by SAP2000 was performed on thirteen 3D models of 12-story RC buildings in order to illustrate the contribution of column stiffness and column cross sections (rectangular or square), building floor plans (square or rectangular), beam stiffness and slab stiffness, on building resistance to an earthquake. The stiffness of the columns contributed more than the beams and slabs to the earthquake resistance of H.R.B.s. Rectangular cross-section columns must be properly oriented in order for H.R.B.s and slender buildings to attain the maximum resistance against earthquakes.

Strength and Cost Analysis of New Steel Sets as Roadway Support Project in Coal Mines

Roadway support in swelling soft rocks in coal mines has become a critical challenge in recent years. For deformation control in swelling soft rocks, high strength sets are preferred in sites. But high strength always means high costs. Therefore, higher strength sets with not too much cost will be more welcomed in situ. Based on this, three new sets, including a floor beam set, a roof + floor beams set, and a roof + floor beams + braces set, have been developed in the present research. Strength comparisons and costs comparisons have been conducted in this research. Results illustrate that compared with the original set, in the floor beam set, the relative strength of bottom corners reaches 2.964, while the relative cost reaches 1.294; compared with the original set, in the roof + floor beams set, the relative strength of the top arch reaches 2.345, while the relative strength of bottom corners reaches 2.964, and the relative cost reaches 1.568; and compared with the original set, in the roof + floor beams + braces set, the relative strength of the top arch reaches 2.635, and the relative strength of bottom corners reaches 5.905, but the relative cost reaches 1.930. Floor beam set and roof + floor beams set illustrate higher strength and not too higher costs than the original set. Although the roof + floor beams + braces set exhibit much higher strength, they also demonstrate much higher costs than the original set. These new sets can be chosen according to different geological conditions in situ.

Determining internal forces in modular building elements under action wind load

The research paper focuses on internal forces determination in the elements of modular buildings under wind load. It provides a methodology for determining dynamic characteristics of a building and for calculating wind loads. This method is based on the following assumptions: coupling of the modules elements is rigid; coupling of block-modules with foundations is hinged-fixed; connection of blocks to each other is hinged in angular points; the floor disk in its plane is not deformed. On the basis of these assumptions the authors derived approximate and refined equations for determining forces in modules elements under static and pulsation components of wind load. The equation of bending moments determination in the pillar bearing cross-section is obtained by approximation of the graph of moments variation, calculated for the spectrum of the ratio of the pillar stiffness and the floor beam in the range from 1/64 to 64. The paper further introduces the calculation results of forces based on the proposed methodology and on the finite element method. The calculations were done while taking different values of wind load and different number of storeys in a building (from 1 to 4 floors). The obtained results are similar, the error does not exceed 5%.

Assessment of Bearing Capacity and Stiffness in New Steel Sets Used for Roadway Support in Coal Mines

There is high demand for roadway support in coal mines for the swelling soft rocks. As high strength steel sets can be taken as an effective alternative to control large deformation in this type of rocks, based on an original set, three new sets, including a floor beam set, a roof and floor beams set, and a roof and floor beams and braces set, are proposed in this research. In order to examine the strengths of new sets, four scaled sets of one original set, and three new sets, have been manufactured and tested in loading experiments. Results indicated that three new sets all exhibited higher strength than the original set. In experiments, the roof beam in set plays a significant effect on top arch strengthening, while the floor beam plays significant effect on bottom arch strengthening. The maximum bearing capacity and stiffness of the top arch with roof beam are increased to 1.63 times and 3.06 times of those in the original set, and the maximum bearing capacity and stiffness of the bottom arch with floor beam are increased to 1.44 times and 3.55 times of those in original set. Based on the roof and floor beams, two more braces in the bottom arch also play a significant effect in bottom corners strengthening, but extra braces play little role in top arch strengthening. These new sets provide more choices for roadway support in swelling soft rocks.

A kind of control technology for squeezing failure in deep roadways: a case study

ABSTRACTUnder high horizontal ground stress, the squeezing failure has been a common failure pattern for deep roadway. And the large deformation of surrounding rock mass around the roadway has also been a major challenge for deep mining practices. This paper describes a case study of the failure mechanisms and stability control technology of deep roadway under high horizontal ground stress in Jinchuan mine in Gansu Province, China. And this paper also aims to propose a kind of support strategy to prevent the plastic slippage around the floor of roadway. This study started with an in situ broken zone measurement programme to determine the depth of broken zone at each part of the roadway. Combined with long bolt and floor beam, an improved support strategy has been proposed. The field test results show that the improved support strategy can successfully solve the problems of side wall collapse and floor heaven. It can significantly restricts rock mass large deformation and avoid frequent repair. Compare to the original support, the improved support strategy can greatly save investment of mines and also has good application value.

Perencanaan Struktur Gedung Kantor Dishub Kota Pagar Alam Berbasis Program SAP 2000

Building construction has a structural component of beams, columns, and plates. Realize a building structure that is able to withstand the loads that work on the building, it is necessary to select the right type of structural materials such as steel strutur, concrete structure and composite structure. The goals of research to obtain the dimensions of beams, columns and plates capable of withstanding loads that worked planning building structure. The analysis of the calculation of dimensions of beams, columns and plates using SAP 2000 program applications that are safe or capable of carrying the planned load of columns 1 and 2 floors using WF 350 x 350 x 12 x 19 and for floors 3 and 4 using WF 300 x 300 x 10 x 15 with BJ 37 steel quality. 1, 2, 3 and 4 floor beams use WF 200 x 150 x 9 x 16 with BJ 37 steel, and 1, 2, 3 and 4 floor plates using K300 Concrete with 12 cm thick BJTS steel quality 30 Ø12 distance of 20 cm (two layers).

Design of Composite Cold-Formed Steel Flooring Systems

Recently conducted experimental and numerical investigations have shown that mobilisation of composite action within systems comprising cold-formed steel beams and wood-based floorboards is feasible and can lead to substantial improvements in structural performance. However, no design rules have yet been established for these systems in order to allow the beneficial effect of composite action to be exploited. In this paper, proposals for the design of such systems are devised and their theoretical basis is presented. At the core of the proposals is the calculation of the attained degree of partial shear connection and the shear bond coefficient for the composite members as a function of the geometric and material properties of their components and connectors. The accuracy of the devised design method for the prediction of moment capacity and flexural stiffness is demonstrated through comparisons with the results of 12 physical tests and about 80 numerical simulations reported in the literature. The proposals provide practical design rules for composite cold-formed steel floor beams, which are suitable for incorporation into future revisions of the Eurocodes.

Experimental study of an innovative modular steel building connection

In modular steel building (MSB) built by unit-prefabricated on-site assembled construction method, connections are critical parts that can strongly influence the overall structural stability and robustness of the MSB. Previous MSB connections mainly use intermediate connecting plates, which may pose practical difficulties to certain modular arrangements or installations. Thus, this paper proposed an innovative MSB connection design with an intermediate plug-in device and a beam-to-beam bolt system as the horizontal and vertical connections, respectively. This connection design can ensure convenient installation, eliminating on-site welding. Two static uniaxial loading tests and four quasi-static cyclic loading tests were conducted on the T-shaped MSB connection to explore its load transfer capacity and aseismic behavior. Results showed that gaps would form between the upper and the lower columns because of its two-unit-joint structure. This gap can influence the deformation patterns and bending demand distributions in each unit joint. The weld quality in the unit joints was critical to ensure overall safety. Stiffeners can effectively strengthen the stiffness and load-bearing capacity. The deformation capacity of the connection was significantly influenced by the stiffness of floor beam–column joint and ceiling beam–column joint as well as the relative magnitudes between them.