Steel-concrete composite beams for slim floors - Specific design features in scope of steel frames design

Abstract

Welded steel beams with trapezoidal box cross-sections and specially punched webs were developed to be preferably applied together with hollow core pre-stressed concrete slabs as composite beams in slim floors. Heights of standard produced Deltabeams copy the range of produced HC-units heights. Utilization of these slim composite beams enables to achieve an effective solution also in combination with filigree or in-situ cast concrete decks. Optimized solutions development from point of view of minimized structural height, high load carrying capacity, simply and very fast erection, versatile utilization and standardized details creates a solid basis for successful and technically efficient usage, not only in scope of concrete, but also steel and composite constructional systems. Reliable solution of fire resistance up to R180, proved by several realized fire tests and supported by appropriate design procedures, eliminates any needs for special on fire case oriented additional structural improvements. Design process in agreement with EC3 and EC4 covers with complexity all the relevant bearing capacity and structural stiffness questions for beams and also for supported slab elements. Specific requirements on acceptable parameters of floor vibrations are covered by experience and tests, carried out on realized structures and supported by suitable calculation models. All unique solutions are verified as a standard by corresponding experimental methods. Utilization of Deltabeams in slim floors is saving constructional heights, reduces energy consumption in buildings, simplifies the realization of constructional cable and pipe lines; parallel to that it significantly reduces time of erection and total costs. Paper presents specific requirements on slim floor Deltabeams in the field of ultimate and serviceability limit states and joint design suitable in steel frames. Requirements on floor vibration acceptance, methods and principles on how to achieve the project defined fire resistances are listed as well. © 2012 Published by Elsevier Ltd.