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High-Rise Buildings

High-rise buildings in the course of history

Technology of high-rise buildings

Risk potential



Mnchener Rck Munich Re Group

ContentsPage 1 2 2.1 2.2 2.3 2.4 2.5 2.6 3 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.3 3.3.1 3.3.2 3.3.3 3.4 4 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 Introduction 4 4.3 4.4 4.5 4.5.1 4.5.2 4.6 4.7 4.7.1 4.7.2 4.7.3 4.7.4 4.8 4.8.1 4.8.2 4.8.3 4.8.4 4.9 5 5.1 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6 5.2 5.2.1 5.2.2 5.2.3 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.5 Fire fighting Organizational measures Atriums Windstorm Earthquakes Foundations, settlement and subsidence Foundations Settlement and subsidence Water Special structural measures Conversions Rehabilitation Demolition Disposal Other risks Terrorism Impact Collapse Wear Loss of profit Insurance Property insurance Contractors and erection all risks insurance Advance loss of profit insurance Insurance of contractors plant and machinery Decennial liability insurance Insurance of buildings, fire insurance Loss of profit insurance Loss of rent Additional costs Contingency planning Prevention of access Third-party liability insurance Insurance of the designers risk Insurance of the construction risk Insurance of the operational risk Problem of maximum loss Construction phase Decennial liability insurance Operating phase Accumulation control Underwriting considerations Contractors and erection all risks insurance Contractors plant and machinery Decennial liability insurance Insurance of buildings, fire insurance Reinsurance Page 110 111 111 111 115 119 119 121 122 122 122 122 123 126 126 126 127 132 132 132 138 139 139 141 142 144 144 145 145 145 145 145 147 147 147 148 149 149 149 149 152 153 153 153 153 153 155

High-rise buildings in the course of history, technology and the environment 8 Historical development Architectural aspects and urban development today Financing models Infrastructural aspects Economic aspects Social and ecological aspects Technology of high-rise construction Planning Planners Regulations and directives Technical analyses and special questions Construction licensing procedure Other constraints Execution Foundations Supporting structure Load-bearing parts Special construction methods Facade Roof Interior finishing Service systems Installations Deliveries, vehicles Passenger transport, vertical development Waste disposal Occupancy Maintenance, administration Conversions Rehabilitation High-rise construction in the future Risk potential Design errors Fire Examples of losses during the construction phase Fire protection on construction sites Examples of losses during the occupancy phase Fire-protection regulations, loss prevention Regulations Structural fire protection Active loss-prevention measures 9 12 14 17 21 21 24 25 25 25 26 26 29 31 31 35 35 42 45 46 46 48 48 49 49 50 51 51 53 53 54 84 85 86 86 89 99 107 107 107 108


Summary and outlook


1 Introduction


Page 5

1 Introduction

High-rise buildings have always triggered major debates and aroused emotion. That is hardly surprising, considering that this type of building radiates more symbolic power than almost any other.


Introduction Up until the end of the last century, high-rise buildings were still made of solid brick masonry, which ultimately required foundation walls up to 1.8 m thick. When steel frames adapted from steel bridge construction were introduced, with their increased strength and lower weight, builders and architects were able to soar to greater heights. With this steel skeleton, the net weight of the structure was considerably lower than that of a solid masonry building; it thus not only cut the costs of construction, but also gave wings to the architects imagination. By the turn of the century, they were designing buildings that also looked light and delicate as even at that time the skeleton structure permitted a large proportion of windows on the outer facade. Since then, the construction of high-rise buildings has continued to change with the requirements imposed by air-conditioning and particularly office communications. The high-rise office buildings of the nineties have little in common with their predecessors. Instead of compact walls and ceilings, we now have a high-tech structure made up of largely prefabricated elements which are welded and bonded together on site. The building comprises a skeleton of steel or reinforced concrete which is rounded off by suspended ceilings and false floors creating the space required for installations. The originally

From their beginning in the middle of the last century and right up to the present day, high-rise buildings have always been a dominant landmark in the townscape, visible from far and wide, like the towers of Antiquity and the Middle Ages. At the same time, this sky-scraping construction method has always been an ideal means of displaying power and influence in the community. In the light of this goal, reasonable economic considerations often recede into the background during the erection and subsequent use of these high-rise buildings. A prestige object for the builder, these edifices not only have an effect on their immediate neighbours, but also influence many areas of urban life in very different ways. These aspects will also be taken up in this publication. In the early years, the builders urge to rise to dizzying heights was limited by unsolved technical problems. In recent years, however, a real competition has developed among the builders of skyscrapers to be world champion at least for a few months before being outdone by a rival with an even higher building. Even seemingly Utopian projects now stand a good chance of becoming reality. This rapid development has only become possible because the technical conditions and methods used in constructing high-rise buildings have improved decisively and in some cases changed fundamentally in the last few years.

1 Introduction

Page 6


load-bearing outer wall has been replaced by a prefabricated facade. However, this complex method of construction promotes the spread of fire and fumes, and therefore, in conjunction with the considerable concentration of values involved, represents an extremely sensitive risk both during construction and throughout the service life of the building. The major fires which broke out in a number of high-rise office buildings shortly before their completion in the early nineties show how correct the appraisal of the fire risk in high-rise buildings is. The losses incurred through these fires are several times higher than the amounts of indemnity known to date. This is consequently one of the main reasons why highrise buildings constitute a new dimension of risk for the insurance industry, one which has made it necessary to draw up new concepts for underwriting, loss assessment and PML determination throughout every phase of construction and subsequent use. We therefore believe that this publication on high-rise buildings is an appropriate addition to our comprehensive series of special publications, particularly those on underground railways and bridges. We are fully aware of the fact that many of the aspects considered with regard to the construction, use and insurance of high-rise buildings naturally apply in the case of lower buildings too. Nevertheless, we do not wish to limit ourselves to aspects which only apply specifically to highrise buildings. After a brief historical overview, we will therefore consider in detail all the risks and problems

associated with high-rise buildings and the techniques that are applied in order to illuminate possible solutions from the point of view of both construction technology and insurance. Moreover, the more broadly based general information available will make it easier not only to assess the risk of high-rise building projects but also to arrive at a price for insuring such projects. The definition of a high-rise building differs from one country to the next. For our purposes, we will proceed on the basis of a minimum height of 30 m and will restrict ourselves to buildings used for residential or office purposes. Despite the various critical voices raised, the construction of high-rise buildings has by no means reached its zenith. The problem of high-rise buildings is one which we as insurers and reinsurers will also have to consider in the future. This special publication is also intended, last but not least, as a means of passing on to others our experience from the major losses that have occurred in the recent past.


2 High-rise buildings in the course of history, technology and the environment

22.1 Historical development 2.2 Architectural aspects

2.3 Financing models 2.4 Infrastructural aspects

2.5 Economic aspects 2.6 Social and ecological aspects


2 High-rise buildings in the course of history, technology and the environment

According to the Bible, the Tower of Babel was to reach unto heaven (Genesis 11).But when the Lord saw what the people had done, He confused their language and scattered them abroad over the face of all the earth so that they left off building the city.

2 2.1

High-rise buildings in the course of history, technology and the environment Historical development edge of the roof was no less than 130 feet (roughly 38 m) above the road surface. Due to its elevator, the upper floors were in greater demand than the lower floors. Following completion of the Equitable building, it was the done thing to reside on one