37º IAHS World Congress on Housing: - Universidad de Cantabria

XXXVII <strong>IAHS</strong><strong>World</strong> <strong>Congress</strong> on HousingOctober 26 – 29, 2010, Santander, SpainCODE: 282EVOLUTION AND SUSTAINABILITY OF IN-SITUCONCRETE FLAT SLABS IN OFFICE BUILDINGSLiébana, O. 1 ; G. Pulido 1 , MD; Gómez Hermoso J. 21University of San Pablo CEU (Madrid), 2 University Politécnica de Madrid1 e-mail: oliebana@ceu.es,Key words: in-situ concrete, sustainability, flat slab, minimum reinforcing ratios, CO 2 emissionAbstractIn the current office building construction practice, flat plate is the most common floorstructural system due to its economic and practical advantages. Traditionally, high materialcosts have had a great impact on total construction cost, so voided options as ribbed or waffleslab have been used extensively. However, recently there is a tendency to design solid slabsoptions, especially due to rising labor costs, simpler and quicker construction, which reducesexecution timeframe and increases construction safety.The use of post-tensioned (PT) floors in building structures has been growing in recent years.This type of construction allows thinner slabs and thus, it creates lighter structures, produces alarge reduction in rebar tonnage, with the subsequent advantages in transportation, storage orlabor. Also, these slabs have other advantages as reduced cracking and deflections, reducedfloor to floor height or quick construction. In most countries these design mechanical andeconomical features have enabled the system to compete economically with traditional in-situconcrete floor slabs; however, this is not the case in some other countries like Spain.Introduction of sustainability criteria and specialization in construction can allow for thissystem to be introduced in the market, which can also mean lower costs, improvedperformance and focusing on sustainability in construction.Different solutions have been studied for an actual project, in terms of material quantities,minimum structural thickness and it has also been checked the impact of costs andenvironmental criteria based on CO 2 emission. With these data, we could assess that thecurrent status of low production of flat slabs in Spain it is not related to real economicreasons; it is actually related to a combination of reasons as lack of technical knowledge ofdesigners or builders, inconsistencies or deficiencies in current national codes in each country.The construction industry is following an inertial period that resists changing known systems,apparently satisfactory, and that especially shows an unsustainable view of the construction.Post-tensioned concrete slabs will not always be the most suitable and sustainable option, butit should be evaluated while considering other more familiar techniques of construction withupdated considerations.37º <strong>IAHS</strong> <strong>World</strong> <strong>Congress</strong> On Housing Science 164