Parametric Study on Composite Beams with Web Openings Fire Protected with Reactive Intumescent Coating

When service ducts and cables are required to pass through the structural beams,it is a common practical solution to use composite beams with rectangular or circular openings.The fire safety standards in many countries have recommended design methods for composite beams without openings,while the design method for composite beams with web openings is not addressed yet.Due to the complicated distribution of temperature and stress around the openings in the web of the steel beam,extra complexity has been introduced in determination of the structural capability of the beam and the failure mode in fire.These failure modes generally occur at lower limiting temperatures than the solid beam with same size.It is recognized that the thickness of a reactive coating required to provide a given fire resistance to a composite beam with web openings is affected by the beam’s web thickness,opening configuration,the degree of the beam asymmetry and the structural utilization factor,as well as the nature of the proprietary fire protection itself.Therefore it is necessary that such beams are structurally evaluated taking into account all possible modes of structural failure under both ambient and fire conditions.It is also necessary for additional thermal data to be measured around the web openings and on the web posts from fire tests.The additional thermal data will be used in conjunction with a structural model to determine limiting temperatures of beams with web openings.Steel Construction Institute(SCI)has produced a structural analysis model referenced as report RT1356,which divides a composite beam with web openings into different stress blocks,and then analyses the global bending,vertical shear,local Vierendeel bending,web-post buckling etc.The Association for Specialist Fire Protection(ASFP)recommended the test protocol in the Yellow Book,to determine the temperature distribution around the openings and web post.This paper will discuss a series of fire tests having been carried out in the laboratory of EXOVA Warringtonfire to establish temperature distribution in composite beams with web openings.Test result shows that the distribution of temperature is product specific and strongly affected by opening configuration and opening distance.EXOVA Warringtonfire has also developed a sophisticated calculator,ThermCalc,for analyzing temperature and structural following the method presented in RT1356.Using ThermCalc,parametric study has been carried out,and the effect of load utilization factor,opening size,opening distance,slab depth,decking configuration etc.was investigated.

Finite element analysis and structural design of pretensioned inverted T-beams with web openings

This paper presents the results of a research project aimed at providing standard circular web openings to the popular precast pretensioned inverted T-beam.Opening size and placement and required materials strengths were investigated.In this paper the nonlinear analysis and design of simply supported pretensioned inverted T-beam with circular web openings are presented.Two design parameters are varied:opening location and number of openings.The results from nonlinear finite element analysis were substantiated by test results from five pretensioned inverted T-beams with web opening and one solid beam.Good agreement is shown between the theoretical and the experimental results.The test results obtained from this investigation show that the performance of the specimens with web openings is almost identical to that of the specimen without web openings.A simple design method for pretensioned inverted T-beam with circular web openings is proposed.

Ultimate load analysis of pretensioned inverted T-beams with circular web openings

The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts,it also translates into substantial economic savings in the construction of a multi-storey building.In this paper,ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented.Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized.An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web open-ings.It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.

Effect of Web Opening on Buckling Instability of Simply Supported Steel I-Beam

The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling instability is not considered in the design codes. In this paper, the effect of web opening on both lateral torsional buckling and local buckling behaviors has been investigated. A simply supported steel I-beam has been studied under uniform bending moment around the major axis. Buckling analysis has been performed using the finite element method. Linear regression analysis has been conducted for output data to formulate an equation for the critical moment including web opening effect. The results have shown a limited reduction in the lateral torsional buckling capacity and a significant reduction in the local buckling capacity.

Structural Performance of Prefabricated Timber-Concrete Composite Floor Constructed Using Open Web Truss Joist Made of LVL Paraserianthes Falctaria

This paper investigates an open web truss joist (OWTJ) made of laminated veneer lumber (LVL) Paraserianthes falctaria as a prefabricated timber-concrete composite floor system. The four-point bending test showed that structural performances of the OWTJ, conventional composite floor (CCF), and prefabricated composite floor (PCF) were similar. Although composite action was not developed as no lateral deformation was observed at the shear connectors, installing a concrete slab above the OWTJ can slightly increase the ductility factor of the composite floor. Furthermore, a finite element model was developed, and the model proved to be suitable for simulating the structural performance of the composite floor.