Civil and Architectural Engineering

Holistic design method for the urban acoustic environment

The aim of the project is to combine subjective and objective parameters in the design of future acoustic environments. A holistic design method for urban acoustic environments will be developed, combining the knowledge gained from decades of soundscape studies, early stage noise mapping, architectural parameters and the fundamental understanding of acoustics.

The intended use of the method is at the earliest design stages, where it can inform decisions that are fundamental for the final outcome of the acoustic environment. The method will be integrated in BIM software and will be therefore be easily accessible.  The results from the method will inform non-acoustic specialists and different stakeholders of how different design solutions influence the acoustic environment. Multi Criteria Decision Making (MCDM) methods will be used to structure the design problem and evaluate multiple conflicting criteria.

With implementation in BIM, using MCDM methods for decision making, the method can become an integrated part of a holistic design process.

ABOUT THE PROJECT


Project title: Holistic design method for the urban acoustic environment

PhD student: Arnthrudur Gisladottir

Contact: arg@eng.au.dk

Project period: Aug 2017 to July 2020

Main supervisor: Prof. Poul Henning Kirkegaard

Research section: Civil and Architectural Engineering


Actual stress estimation

Marius Glindtvad Tarpø

Offshore structures accumulate damage during operation because environmental and operational forces vary and fluctuate continuously. The irregular forces cause propagation of cracks, which leads to fatigue failure. The practical design of offshore structures allows for these uncertainties by simplifying reality.

Many offshore platforms in the North Sea are reaching the end of their designed lifetime, but the actual integrity of the structures is unknown. This project aims to obtain better knowledge of the actual stresses during operation by the use of tools like operational modal analysis. This knowledge might lead to a better understanding of the remaining lifetime of the existing structures in the North Sea.

ABOUT THE PROJECT


Project title:  Actual stress estimation

PhD student: Marius Glindtvad Tarpø

Contact: martar@eng.au.dk

Project period: Aug 2017 to July 2020

Main supervisor: Prof. Christos Georgakis

Co-supervisor: Rune Brincker (DTU)

Research section: Civil and Architectural Engineering


Wave measurements using LIDAR

Cases of extreme waves at or in the vicinity of offshore platforms have recently been identified. The most recent accident in the North Sea involved an extreme wave generated slamming load on the COSL Innovator, which lead to broken windows, the deformation of the forward bulkhead and the loss of one life. Based on the aforementioned observations and events, it is becoming increasingly clear that structural safety may well be dominated by the large level of uncertainty related to the probability of the occurrence of breaking waves and their associated loads. Therefore, it is of vital importance that an improved method of measuring waves is investigated.

Recently, a set of advanced LIDAR measurement systems has been purchased, the first of which is installed on a platform in the North Sea. This system is capable of recording surface elevation data over an area of roughly 200 by 200m, with a claimed accuracy of 10cm in the vertical. This project will characterise and validate the accuracy of the surface elevation measurements, establish data handling and processing protocols, and develop a unique database of full-scale, breaking wave events for use in validating numerical models and developing statistical load cases. Ideally, one LIDAR system will also be installed over the course of this project on an instrumented pole at an approximately 1:10 scale coastal facility to provide additional data for comparison.

ABOUT THE PROJECT


Project title: Wave measurements using LIDAR

PhD student: Thomas Kabel Pedersen

Contact: tk@eng.au.dk

Project period: June 2017 to May 2020

Main supervisor: Prof. Christos Georgakis

Co-supervisor: Robert Read (DTU MEK)

Research section: Civil and Architectural Engineering


Effective indoor climate and air quality control via optimal ventilation air distribution

Khem Raj Gautam

This PhD project focuses on the optimal design and air distribution control of hybrid (integrated natural and mechanical) ventilation systems and the application in large buildings including public, agricultural and industrial buildings.

The research involves laboratory and field investigations, CFD (Computational Fluid Dynamics) modelling and simulations, characterisation of air motion in a room, heat mass transfer in the boundary layer and controlled experiments for hypothesis testing.

The major activities include investigation of the air motion in ventilated room spaces using varied ventilation design, system configurations and control, as well as the effects of indoor partitions, equipment and occupants. An important focus is on air distribution in intensively occupied large room spaces. Such knowledge is key to achieving an optimal solution for a desired indoor thermal climate and air quality.

ABOUT THE PROJECT


Project title:  Effective indoor climate and air quality control via optimal ventilation air distribution

PhD student: Khem Raj Gautam

Contact: krg@eng.au.dk

Project period: May 2017 to April 2020

Main supervisor: Senior Researcher Guoqiang Zhang

Research section: Civil and Architectural Engineering


Optimizing refurbishment projects through lean processes

Hasse Højgaard Neve

Refurbishment or renovation of housing buildings are a challenge worldwide and well debated both in industry and in academia. The construction industry consumes up to 40 percent of the total energy production. The construction industry is therefore under pressure to radically reduce the energy consumption, both in the use phase (operational energy) and in the manufacturing and construction process (embedded energy). 75 percent of all constructions we have today will still exist in the year 2040. To reach the ambitious energy targets much more knowledge about how to optimize refurbishment processes is needed.

In new building projects, we have already succeeded in increasing productivity radically and to reduce waste and thereby the embedded energy consumption of construction by implementing lean based tools and principles. However, in refurbishment projects, knowledge about implementation and the effect of lean construction principles is limited, which also indicates an unexploited potential for sustainable renovation processes.

This research will continue to investigate the potential sustainable effect that lean processes can have on the construction process in refurbishment projects.

ABOUT THE PROJECT


Project title: Optimizing refurbishment projects through lean processes

PhD student: Hasse Højgaard Neve

Contact: hn@eng.au.dk

Project period: Feb 2017 to Jan 2021

Main supervisor: Prof. (Docent) Søren Wandahl

Research section: Civil and Architectural Engineering


Soil-pile interaction in soft soils

Jakub Kania

Precast driven piles or cast-in-place bored piles are often used in connection to construction work on sites with soft soil conditions. If the upper layers of soft soil later experience settlement, then the piles will, in addition to the building load, also be affected by a downwards acting force (termed negative skin friction or down drag) resulting from the adhesion between the soil and the pile in those layers which settle relative to the pile.

Hence, a reliable assessment of negative skin friction is a vital part of pile design when piles are installed in soft ground conditions. However, current guidelines and design practice in Denmark are believed to be overly conservative due to limited understanding of the governing mechanism and limited knowledge regarding the effect of pile material and ground conditions on the development of negative skin friction. Especially the influence of bitumen coating on the development of negative skin friction is poorly understood and in Denmark and also generally in the Nordic countries, there exist only very limited documentation to prove the actual effect of bitumen coating.

ABOUT THE PROJECT


Project title:
Soil-pile interaction in soft soils

PhD student: Jakub Kania

Contact: jgk@eng.au.dk

Project period: Oct 2016 to Sept 2019

Main supervisor: Prof. (Docent) Kenny Kataoka Sørensen

Research section: Civil and Architectural Engineering


InDirect Estimation of Loads from Abnormal Waves

Michael Vigsø

Large breaking waves has been observed in areas of the North Sea that are normally not encountered. The potential impact of these extreme breaking waves on offshore installations is yet to be fully understood. Despite numerous models on load estimates from breaking waves by recognised parties such as DNV GL, the full-scale impact from these extreme waves remains uncertain. Many small-scale tests have been conducted with the aim of describing the kinematics of the breaking waves. However, due to the nature of the breaking wave such as nonlinearities and significant scaling effects, further investigation is needed in order to evaluate the response on real structures.

The aim is to use system identification techniques such as Operational Modal Analysis, OMA, and Autoregressive Moving Average, ARMA, to evaluate indirectly the effect of extreme sea states on offshore installations through the structural response. Throughout the project, the objectives are to gather new knowledge about wave loads and statistics of abnormal waves and possibly improve the basis of design. 

The project is carried out in close co-operation between Department of Engineering at Aarhus University and the Danish Hydrocarbon Research and Technology Centre DHRTC, also referred to as Centre for Oil and Gas – DTU.

ABOUT THE PROJECT


Project title:
InDirect estimation of loads from abnormal waves

PhD student: Michael Vigsø

Contact: mvigso@eng.au.dk

Project period: Sept 2016 to Aug 2019

Main supervisor: Prof. Christos Georgakis

Research section: Civil and Architectural Engineering


Energy renovation of social housing units - added value through architectural transformation

Stina Rask Jensen

The building sector is responsible for 40-50 percent of the total European energy consumption. Adding to this, 75 percent of the existing Danish building mass is expected to be in operation by 2040. This makes energy renovations an important area of focus in the years to come.

There is an estimated number of 600.000 social housing units in Denmark of which a considerable number were built before the national building regulations were tightened in 1979. As such, there is an identified potential for reducing the overall energy consumption in the building sector by addressing this particular typology through energy renovations.

The challenge of transforming the building mass to be more energy-efficient not only calls for separate technical development and innovation, but for a holistic approach which considers both quantitative and qualitative aspects with special attention to the occupants. This PhD project aims to develop guidelines for architectural transformation, which can help articulate and realise the potential for added cultural and social value within the technical transformation processes. The project has an application oriented focus, taking its point of departure in Research through Design as the overall methodological framework. 

ABOUT THE PROJECT


Project title:
Energy renovation of social housing units - added value through architectural transformation

PhD student: Stina Rask Jensen

Contact: srj@eng.au.dk

Project period: Aug 2016 to July 2019

Main supervisor: Prof. Poul Henning Kirkegaard

Co-supervisor: Anders Strange, partner and CCO, AART Architects

Research section: Civil and Architectural Engineering


Change Management i Building Performance: An Engineering Design Methodology for Sustainable Retrofitting

Aliakbar Kamari

A sustainable energy sector has a balance in energy production and consumption and has no, or minimal, negative impact on the environment (within the environmental tolerance limits). It allows for the opportunity for a country to employ its social and economic activities. It can be seen as the final goal: a balance of social activities, economic activities and the environment. In this framework, compounding the typical challenges of retrofitting implementation, due to the potential of different types of stakeholders, is the lack of a comprehensive methodology to enhance both communication in a learning process among different stakeholders and multi-optimisation among different criteria in a sustainable perspective.

Therefore, in a real sustainable retrofitting context, an understanding of the level of connectivity and level of criticality of the dependencies (building features, limitations, constrains, etc.) is required initially towards application of an appropriate decision support system which needs to be embedded in the early design stages (conceptual design phase).

The motivation for this research is related to identifying and developing a suitable methodology to carry out and improve learning using a mix of methods. This involves the application of systematic approaches to identify and catch the complexity in retrofitting of existing buildings when dealing with complex problems and multiple decision makers as well as multiple criteria based on a holistic vision. It also includes considering and addressing the processes involved in an optimised retrofitting process among the existing alternatives using MCDM methods.

ABOUT THE PROJECT


Project title:
Change Management in Building Performance: An Engineering Design Methodology for Sustainable Retrofitting

PhD student: Aliakbar Kamari

Contact: ak@eng.au.dk

Project period: Jan 2015 to Dec 2017

Main supervisor: Prof. Poul Henning Kirkegaard and Prof. Rossella Corrao, Department of Architecture, University of Palermo

Research section: Civil and Architectural Engineering


Direct measurements of wave forces from abnormal and breaking waves

Julie Carøe Kristoffersen

Offshore structures are increasingly exerted by extreme loads from abnormal waves and breaking waves. The breaking wave introduces high loads including impulsive load contributions resulting in dynamical response of the offshore structures. The nature of breaking waves is highly nonlinear with following complex mechanism of the impact on the structures.

Many different approaches have been taken previously to investigate the impact forces such as computational methods, analytical and wave basin measurements in smaller and larger scale. The focus of this project will be to study measurements of forces from abnormal and breaking waves in wave tanks and, eventually, experimental investigations in the open sea. The main goal is to examine the amplification of wave loads due to extreme seas, and be able to describe the essential physical mechanism and statistics of abnormal and breaking waves.

ABOUT THE PROJECT


Project title:
Direct measurements of wave forces from abnormal and breaking waves

PhD student: Julie Carøe Kristoffersen

Contact: jck@eng.au.dk

Project period: May 2016 to April 2019

Main supervisor: Prof. Christos Georgakis

Research section: Civil and Architectural Engineering


Performance simulations and information flow in building information models

Pil Brix Purup

The building design industry is challenged by increased demands regarding energy as well as thermal comfort, air quality and daylight. These demands require that design decisions in the early design stage are based on careful considerations about their potential impact on energy efficiency and environmental comfort. To ease this design task, there are research-based efforts focusing on enhancing efficient use of performance simulations as design support. However, there seems to be a low uptake of these research efforts in professional design practise. A reason might be that current proposals for procedures interpret wrong what architects actually need. Therefore, the approach seems rather to adapt the performance simulations to fit the design practise, than suggesting new procedures.

Another issue known from practise is that knowledge and information regarding functional demands, which is carefully selected in the early design stage, is often lost when replacing people in transition between design phases. The performance of the final building is consequently not fulfilling the initial intentions and demands, resulting in costly remediation.

This PhD project aims to develop performance simulations conformed to fit the design practise, as well as appropriate protocols for information flow through building design phases. Both embedded in building information model (BIM), and tested through case studies of building projects in the industry. Thus, performance will, hopefully, be considered in the early design phase, and valuable information will become the basis for the subsequent design phases.

ABOUT THE PROJECT


Project title:
Performance simulations and information flow in building information models

PhD student: Pil Brix Purup

Contact: pil@eng.au.dk

Project period: Feb 2016 to Jan 2019

Main supervisor: Assoc. Prof. Steffen Petersen

Co-supervisor: Hanne Schwarz (ALECTIA A/S)

Research section: Civil and Architectural Engineering


Dynamic modelling of ventilation airflow and indoor air quality in naturally ventilated buildings

Qianying Yi

Natural ventilation is extensively used in intensive livestock production systems. Maintaining desired environmental conditions contributes to the productivity and welfare of the animals in the livestock buildings, which is dependent on the design and control of the ventilation system. On-line measurement or estimation of ventilation airflow rate is important for control of indoor thermal condition, air quality and airborne contaminant removal via building ventilation. However, such a measurement or estimation is a challenge for a naturally ventilated system.

Thus, the objectives of the project are to develop, investigate and validate a new modelling concept for describing the airflow characteristics and estimation of ventilation airflow rate in a naturally ventilated building based on building configuration geometry, wind conditions, etc. The hypothesis is that the characteristic link between indoor air and wind for a defined building structure and varied ventilation openings can be found based on spectral analysis of measured flow data.

In order to achieve this goal, the project will use both a numerical modelling method and analysis of the field data collected in field measurements to discover the approaches for a dynamics modelling of indoor airflow and estimation of the total ventilation rate of a naturally ventilated building.

ABOUT THE PROJECT


Project title: 
Dynamic modelling of ventilation airflow and indoor air quality in naturally ventilated buildings

PhD student: Qianying Yi

Contact: qianying.yi@eng.au.dk

Project period: Oct 2015 to Sep 2018

Main supervisor: Senior Researcher Guoqiang Zhang

Research section: Civil and Architectural Engineering


Development of retrofit solutions for utilisation of the smart grid potential in existing one-family dwellings

Rasmus Elbæk Hedegaard

The Danish Government has issued that by 2050 the total energy production in Denmark entirely based on renewable energy sources. Renewable energy production introduces a range of new challenges in relation to ensuring both grid stability and energy security.

To address these issues, research in smart energy technology has been on a steady incline throughout recent years. A smart energy system is by definition an energy distribution system that is able to take information about consumption and production rates into account, but also to distribute such information between energy system actors to increase energy efficiency and security.

This PhD project aims at investigating the potential of introducing smart energy technology in existing one-family dwellings, before and after a retrofit has been carried out. The work is intended to identify the economically viable balance between investments in energy savings and smart energy management during a building retrofit.

ABOUT THE PROJECT


Project title: 
Development of retrofit solutions for utilisation of the smart grid potential in existing one-family dwellings

PhD student: Rasmus Elbæk Hedegaard

Contact: reh@eng.au.dk

Project period: Aug 2015 to July 2018

Main supervisor: Assoc. Prof. Steffen Petersen

Research section: Civil and Architectural Engineering


Optimisation of building retrofit in an integrated energy system based on renewable energy

Martin Heine Kristensen

Old buildings account for much of the energy consumed in society and need to be energy renovated and retrofitted in order to cope with the ambitious political goals requiring a more sustainable and flexible energy supply, based on renewable energy technologies. But how do we identify the optimal retrofit solutions that we should rely on?

The PhD project aims at setting up a platform/tool to quantify the operational energy demand and demand-side flexibility of the different types of buildings in a city district depending on their application, location, construction year etc. The purpose of the platform is to enable the identification of cost-optimal solutions that minimise the life-cycle energy need (i.e. include embodied energy), maximise the demand flexibility and guarantee high-quality indoor environments for the end-user. These solutions should not only consider the performance of individual buildings but the whole city district including operation of the energy supply. 

The platform/tool is initially set up and calibrated using Aarhus energy district as case study, but should be generally applicable when finalised.

ABOUT THE PROJECT


Project title: 
Optimisation of building retrofit in an integrated energy system based on renewable energy

PhD student: Martin Heine Kristensen

Contact: mhk@eng.au.dk

Project period: Aug 2015 to July 2018

Main supervisor: Assoc. Prof. Steffen Petersen

Research section: Civil and Architectural Engineering


Development of retrofit solutions for utilisation of the smart grid potential in existing residential buildings

Theis Heidmann Pedersen

Project description:
The Danish Government has passed an agreement that by 2050 the total energy production in Denmark should constitute of renewable energy sources. This implies a new challenge as renewable energy production is fluctuating with weather conditions. Therefore, a flexible relation between the consumers and producers, referred to as smart energy, is necessary.

Taking offset in the retrofit demonstration project READY, this PhD project aims at investigating the smart energy potential in existing residential buildings. Retrofit solutions that increases the buildings' smart grid potential is then identified and tested in an actual retrofit case. The objective is to set up a general methodology for targeting and quantifying the effect of different energy flexibility technologies related to energy retrofit of buildings.

ABOUT THE PROJECT


Project title: 
Development of retrofit solutions for utilisation of the smart grid potential in existing residential buildings

PhD student: Theis Heidmann Pedersen

Contact: thp@eng.au.dk

Project period: May 2015 to April 2018

Main supervisor: Assoc. Prof. Steffen Petersen

Research section: Civil and Architectural Engineering


Pore water pressure response and heave of Palaeogene clays in connection to deep excavation and pile driving

Thomas Rye Simonsen

Constructions in the city centers have changed over the last 10-20 years. The buildings are increasingly getting higher, moving into coastal areas and more often include excavations for multi-story basements. When removing a large amount of soil due to deep excavations the foundation substrate is relieved from a massive load – often even when the weight of the building is included. When building in areas with clay of high plasticity (Palaeogene Clay) near the surface, the relieving pressure on the underlying substrate pose a challenge. Deep excavations generate negative pore water pressures within the clay which cause the soil to heave. However, it is believed that positive pore pressures generated by pile driving can reduce the subsequent heave.

Through literature/archive study, field monitoring at construction sites and testing in the laboratory we aim at extending our current knowledge of the pore pressure development and ground deformations in connection to pile driving in combination with deep excavations in clay. The results of the work should provide the basis for the development of an analytical method which can be used to predict ground deformations and pore pressure development in Danish Palaeogene Clays. The project will furthermore aim at establishing guidelines of how to include the partial equalization of the pore pressures in the design of future foundations.

ABOUT THE PROJECT


Project title:
Pore water pressure response and heave of Palaeogene clays in connection to deep excavation and pile driving.

PhD student: Thomas Rye Simonsen

Contact: thrs@eng.au.dk

Project period: April 2015 to March 2018

Main supervisor: Prof. (Docent) Kenny Kataoka Sørensen

Co-supervisor: Nik Okkels, Geo

Research section: Civil and Architectural Engineering


Adaptive Smart (Natural) Ventilation Control for Cattle Housing and Integrated Climate Sensing

Xiaoshuai Wang

Natural ventilation is an increasingly popular approach to offer a good indoor climate without any mechanical technology aid. Comparing with the mechanical ventilation, natural ventilation has a very significant advantage in terms of energy savings. However, obvious defects such as the absence of precise control of the air movement, vulnerability to the persistent severe situation and lack of adaptability restrict the natural ventilation in becoming more widespread. Therefore, innovative design and control are needed to improve its performance to ensure optimal indoor climate.

To achieve this goal, knowledge on animal heat loss and thermal well-being influenced by air temperature, speed, radiation and evaporation effects in a space is crucial.

The aim of this project is to develop an adaptive smart (natural) ventilated barn for cattle. An investigation of integrated climate sensing methods and precision zone ventilation techniques will be conducted. Both experiment and numerical simulation methods will be applied in the project.

ABOUT THE PROJECT


Project title:  
Adaptive Smart (Natural) Ventilation Control for Cattle Housing and Integrated Climate Sensing

PhD student: Xiaoshuai Wang

Contact: xiaoshuai.wang@eng.au.dk

Project period: Oct 2014 to Sept 2017

Main supervisor: Senior Researcher Guoqiang Zhang

Co-supervisor: Prof. Christopher Choi, University of Wisconsin, USA

Research section: Civil and Architectural Engineering


Annette Beedholm Rasmussen

Annette Beedholm Rasmussen

Analytical and Numerical Modelling of Reinforced Concrete including Tension-Stiffening Effects

Project description:
Initially when designing reinforced concrete structures, focus is on the ultimate limit state (ULS), assuring the structure's strength by preventing failure from happening. Afterwards, the serviceability limit state (SLS) is investigated where stress limits as well as requirements concerning crack widths and deformations should be met. Due to the fact that stress levels and crack development are highly dependent on the reinforcement ratio and configuration, the choices made in the ULS concerning the design of the reinforcement have a high impact on the behaviour of structures in SLS.

The stiffness of a material with non-linear behaviour like reinforced concrete is closely associated with the level of crack development. Though, often, the material is assumed fully cracked or not cracked at all where the effect of tension-stiffening is disregarded. This can have consequences on the behaviour, for example in statically indeterminate structures where the static system in the elastic stage is dependent on the stiffness.

Tension-stiffening is an effect that causes the stiffness to be considerably larger than the one of a fully cracked member. The concrete between adjacent cracks is modelled to carry tensile stresses which are transferred from the reinforcement to the concrete by means of the bond.

The aim of this project is to establish the link between ULS and SLS through understanding of the actual physical behaviour. This will be described through analytical models based on concrete mechanics combined with principles of elastic energy. Advantage is taken of numerical modelling to support experimental results as well as to investigate relevance and reliable magnitudes of different material parameters concerning tension-stiffening.

ABOUT THE PROJECT


Project title:
Analytical and Numerical Modelling of Reinforced Concrete including Tension-Stiffening Effects

PhD student: Annette Beedholm Rasmussen

Contact: abra@ase.au.dk

Project period: May 2014 to April 2019

Main supervisor: Prof. (Docent) Lars German Hagsten

Research section: Civil and Architectural Engineering

 

 


Automated Operational Modal Analysis

Peter Olsen

In the future, the application of Structural Health Monitoring (SHM) will be a key element when considering structures such as large span bridges, high-rise buildings or wind turbines.

SHM is a network of sensors placed wisely on the structure, monitoring the physical parameters of the structure. The sensors inform the control centre or the maintenance crew if any change in the structure is detected revealing crack growth or failure of secondary structural elements. This increases the safety of the structure and makes it possible to replace parts or fix the structure before failure.

The SHM system consists of sensors and an analysis part to process the measured signals. In this process, the identification of the structures’ physical parameters is essential. As it will be an enormous amount of data which have to be analysed, this procedure will have to be automated.

The focus of this project is on Automated OMA. OMA is short for Operational Modal Analysis and is used in modal testing to find the modal parameters such as eigenfrequency, modeshapes and damping ratio of a machine or a structure. The process of automating the estimation process when working with OMA demands development of an algorithm that is stable and need no interaction from the user.

The main objective of the project is to investigate the use of well-known identification techniques in both time domain and frequency domain in combination with filtering techniques to automate the identification process. The identification of several criteria for choosing the physical parameters is another main focus of the project.

ABOUT THE PROJECT


Project title:
Automated Operational Modal Analysis

PhD student: Peter Olsen

Contact: pto@ase.au.dk

Project period: Nov 2012 to Oct 2017

Main supervisor: Prof. Rune Brincker

Research section: Civil and Architectural Engineering