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.