Revision of European Building Code En1991 for Static and Dynamic Roof Loading by Volcanic Ash

Abstract

This thesis presents a numerical procedure for testing the effects of both static and dynamic loading of volcanic ash deposition on concrete roofs. The study aims to propose changes by adding additional action (i.e., volcanic ash loads) to the building regulations to make existing and future European buildings more robust. The investigation uses a Multiphysics simulation approach. A mathematical model is developed to investigate the volcanic ash effects in the context of the EN1991 code. A numerical modelling tool (EDEM software) to implement the Discrete Element Method DEM and a structural analysis tool (ANSYS) for the Finite Element Method (FEM) is used to investigate the scaled models, which are used to subject the pressure loads considering the wind and no-wind effects. The modelling and simulation tests accounted for wind effects, various volcanic ash sizes and the density of the ash material. Still, it can be changed to reflect a range of relevant (measured) eruptive products. The key parameters and the results are illustrated as follows. While using DEM and FEM simulation results, various diameters were used. The modelling technique has been able to interrogate the exploration of the volcanic ash loading effects of various geological and environmental conditions during deposition.

The number of simulated volcanic particles of 160,000, the density of 3000 (kgm-3) for the flat concrete roof and volcanic particle 170,000, and 1000 (kgm-3) density for the 20 degrees pitched concrete tile roof. The variable densities will enable the study to have a different perspective on the effects of stress and the deformation of the volcanic ash particle on the roofs of buildings. The Simulated flat concrete roof for the volcanic ash particles diameter results for wind effects in the horizontal direction of (1 ms-1) are as follows: the volcanic ash particles diameter for 10 mm the DEM maximum Pressures 8581.1 (Pa), the FEM maximum deformation as 0.081 (mm) and the FEM maximum stress as 4.424 (MPa). The no wind effect (controlled condition) simulations particle variable results are as follows:

the DEM maximum pressures aas 4716.3 (Pa),

the FEM maximum deformation as 0.040 (mm) and

the FEM maximum stress as 2.074 (MPa)

The Simulated pitched tile roof for the volcanic ash particles diameter results for wind effects in the horizontal direction of (1 ms-1) are as follows: the volcanic ash particles diameter for 10 mm the DEM maximum Pressures 3472.2 (Pa), the FEM maximum deformation as 0.70084 (mm) and the FEM maximum stress as 11.988 (MPa). The no wind effect (controlled condition) simulations particle variable results are as follows: the DEM maximum Pressures 940.33 (Pa), the FEM maximum deformation as 0.17444 (mm) and the FEM maximum stress as 2.6009 (MPa). As expected, the wind effect resulted in an uneven distribution of the ash on the roof surface, which in turn produced areas of high-pressure load and stress levels. These results will have a possible impact on the designs of buildings on flat roof considerations. The thesis concluded its study by proving the need for the proposition of European building code EN1991-1-1-4 for volcanic ash load arrangement on the roofs of buildings within volcanic prone areas in Europe.

The Implication of the Results

The study aims to investigate the resilience of building roofs against the load due to volcanic ash weight in the volcanic prone area of Europe and propose a revision of the European building code EN1991 (in the current European code regulation) within the volcanic prone areas in Europe. These aims are directly linked to the study's objectives and focus on the gap and contribution to the research. That is the effect of the volcanic ash on the roofs of buildings within the volcanic prone areas, as this wasn’t part of the European building code E1991.

The study could ascertain the effects of the volcanic ash loading using static and dynamic approaches on the roof of the building within the volcanic prone area using the DEM and FEM simulations as illustrated in objective 3. Furthermore, the results of the study have indicated in chapter 5 the effects of the variable volcanic ash densities (1000 kg/m3, 2000 kg/m3 and 3000 kg/m3) that have led to the collapse of buildings within the volcanic prone areas in Europe as indicated by the study.

This part of the recommendation relates to objective 1, and objective 2 illustrates the research's contribution to the geographical distribution of the regions that will benefit all volcanic-prone areas in Europe from the revision of the building regulation. However, Europe will benefit from this study, but the world at large with countries' experiencing the effect of volcanic ash loadings on the roofs of buildings.

The proposal of the revision of the EN1991 is linked led to objective 4 clearly shows that the

results from the various tests indicated the impact of the volcanic ash effects on the roof within the volcanic prone area in Europe. Furthermore, it was clear that the buildings with flat concrete roofs would be more impacted than the pitched roofs within the volcanic prone.

As already indicated, the preliminary simulation test for the tile pitched roof, with the angle of inclination from 35 degrees to 45 degrees, shed most of the volcanic ash on its roof, resulting in less deformation and stress on the roofs. The study, therefore, recommended the strengthening of all those flat roofs as follows:

All existing flat roofs should be retrofit or structurally reinforced to increase the roof's resilience against the volcanic ash loading effects.

Flat roofs should not be encouraged in the design of new buildings within the volcanic prone areas unless buildings designers can increase the strength of buildings with flat roofs within the volcanic prone areas in Europe and the world at large.

3) All existing pitched roofs in the volcanic ash-prone areas should be retrofit or structurally reinforced to increase the roof's strength.

Existing pitched roofs within the range of 20-30 degrees are prone to roof failures. Therefore, they must not be encouraged in volcanic prone areas unless they can be retrofit or structurally reinforced to increase the roof's resilience against the volcanic ash loading effects.

Pitched roofs buildings with steep roof angles that can flash off the volcanic ash quickly must be recommended within the volcanic prone areas as that helps sheared off the deposition of the volcanic ash loading on the roofs.

This measure means cost implications for owners of buildings within the volcanic-prone areas.

This approach will require government support to avert situations where buildings will collapse and kill people in volcanic-prone areas.

Existing pitched roofs with an angle of inclination between 20-30 degrees should be retrofit to increase the strength of the roofs within the volcanic-prone areas. However, this will need government and political will to undertake such a policy to avert a situation of the hazard of the collapse of the pitched roof within the angle of inclination affected during a volcanic eruption.

The study recommended that newly built buildings should be encouraged to use pitched roofs with steep a steep roofs angle that can flash off the volcanic ash quickly must be recommended within the volcanic prone areas as that will help sheared off the deposition of the volcanic ash loading on the roofs.

Though the designs approach will increase the cost of buildings within the volcanic-prone areas in Europe and the rest of the world, it will help avert the hazard of volcanic ash loading leading to the collapse of roofs of buildings in the volcanic-prone areas and save lives. Every life matters and people who live in the volcanic prone areas in Europe and the rest of the world matter.

This study approach will help make buildings within the volcanic prone areas more resilient against the volcanic ash particle loadings on the roofs and will also contribute to Knowledge.

Date of Award	May 2022
Original language	English
Supervisor	Nick Petford (Supervisor) & Stefan Kaczmarczyk (Supervisor)