The influence of the structural possibilities on the transition point between demolition and transformation of multi-story concrete office building structures

The influence of the structural possibilities on the transition point between demolition and transformation of multi-story concrete office building structures

Vermond, M.

Nijsse, R. (mentor)
Pasterkamp, S. (mentor)
Braam, C.R. (mentor)
Robbemont, A.J. (mentor)

Civil Engineering and Geosciences

Building and Stuctural Engineering

2015-04-24

Since the crisis in 2008 affected the global financial market, the economic climate changed drastically. A significant increase in the amount of vacant office buildings was introduced. Combining this fact with the increasing demand for living space in urban areas, transformation of vacant office buildings to residential buildings seems to be a simple solution to the problem. Redevelopment and transformation of vacant office buildings experience however many obstacles. Research into the structural opportunities of vacant office buildings could be helpful to overcome several obstacles. Due to the complexity of the projects, transformation asks involvement of many parties in an early stage of the development. The developers consult several advisors on financial, structural and architectural aspects. The aim of this research is creating a better understanding of transformation possibilities, emphasizing on the structural modifications of the transformation plan. The investigation answers the main research objective; the influence of the structural possibilities on the transition point between demolishing and transforming multi-story concrete office buildings. The building structures within this research exist of reinforced concrete and are built between 1950 and 1980. The transformation plan changes the office building function to residential function. An assessment tool is composed during the design study and consists of general- and structural selection criteria. This assessment tool is used to obtain a good and comprehensive understanding of the transformation potential. If the buildings have passed the veto criteria ( (1) demand for housing and (2) the environmental regulations), they have been examined to the general selection criteria. If the results are below 50% of the maximum achievable score, the building is not suitable for any further investigation. These buildings are omitted in the next step; the selection criteria of the structural aspects. The aim of this intermediate examination step is to gain a better view on the structural aspects of the potentiometer. Eight potential projects have passed the selection criteria and have been clustered in three groups; low-, medium- and high transformation potential. Two buildings have been chosen for further investigation during the design study; the Shell-building and Cool75, both located in the center of Rotterdam. The architectural design and the corresponding structural modifications have been analyzed on their feasibility. The results of the investigated case study projects correspond with the outcome of the selection criteria. Important structural aspects of successful transformation projects are the availability of original information, the possibility to attach balconies to the current structure and vertical expansion. Other important influences on the transition point between demolition and transformation of the existing office building structure are the free floor height and the installation of ducts in horizontal and vertical direction. The adjustability and flexibility of the structural layout are remaining important factors, flexible floor plans enlarge the feasibility when a change of function is investigated. The strength and stability of the existing structure with the implemented change of function have to be checked on the structural key factors; (1) the horizontal deformation at the top, (2) the shear forces in the normative lintels, (3) the axial forces on the foundation piles and (4) the compressive and tensile stresses of the stabilizing elements. The structural key factors are applicable for a larger range of similar building structures. If the structural key factors fulfill the requirements according the Eurocode, the structural performances of the existing structure on vertical expansion, attachment of balconies and other possible structural modifications have to be investigated. If the structural key factors do not fulfill the requirements, there has to be looked into the integration of required structural modifications which also lead to an increase of the architectural and economic value of the building. The maximum wind load exposure according Eurocode 1-4 is significantly higher for tall buildings than the TGB 1955. The wind loads have a large influence on the bending moment at the bottom of the core and the horizontal displacement at the top of the tower. The Shell-building shows an increase in bottom core moments of ±50% in SLS and ±25% in ULS. The increment of the wind loads is an important factor to the structural performances of office buildings with an equivalent height. The wind load of low-rise buildings is not significantly increased. An important aspect on the transition point is the relation between the structural modifications and the economic revenues of the structural modifications. To determine the transition point between demolishing or transforming an office building, the structural modifications should be justified on economic reasoning. Due to the comprehensive field within the transformation market of office buildings, not every design and feasibility aspect is considered during this investigation. More research needs be done on the structural performances and visual assessment of the case study projects. Furthermore, not all non-structural transformation motives have been taken into consideration. These aspects are open for further investigation.

http://resolver.tudelft.nl/uuid:d328ba02-6e62-4cbb-b2dc-fdadf2754832

2015-04-24

Student theses

master thesis

(c) 2015 Vermond, M.