Ibell Tim

University of Bath | UB · Department Architecture and Civil Engineering

The construction industry is responsible for a considerable share of the carbon emissions annually. Despite the wide body of literature addressing the embodied carbon of superstructures, limited attention is given to the embodied carbon of substructures. This research introduces an optimization algorithm to minimize the embodied carbon of deep foun...

ABSTRACT: Many studies have addressed the embodied carbon of superstructures, however, the carbon footprint of substructures has only been investigated to a limited extent. This study aims to optimize the design of reinforced concrete piles through finding the best combination of concrete design parameters, this is done using a hybrid-optimizatio...

Concrete production and construction are responsible for a considerable share of the total carbon emissions annually. With the emerging need to cut carbon emissions from the construction sector, there has been a big interest in optimising the embodied carbon of superstructures. However, limited attention is given to optimising the embodied carbon o...

The construction industry is one of the main contributors to the increasing carbon emissions globally. With an increasing interest in optimising the embodied carbon of superstructures, very little attention is paid to optimising the embodied carbon of substructures although foundations are responsible for a considerable share of the total carbon em...

A recent UN report shows that the construction industry was responsible for around 37% of CO2 emissions in 2020. Many studies have addressed the carbon footprint of superstructures and proposed innovative designs with a lower carbon footprint. However, the carbon footprint of substructures has only been investigated to a limited extent due to a lac...

The latest available high-level top-down analysis shows that the embodied carbon of the UK construction in 2018 was 43 MtCO 2e , of which 80% came from materials and on-site activities. In this paper, for the first time, we combine a detailed bottom-up model of representative residential and non-residential buildings with top-down infrastructure an...

A recent UN report has shown that the construction industry is one of the seven major sectors that contribute significantly to environmental pollution and was responsible for around 20% of energy-related CO2 emissions in 2020, and this is expected to increase during the upcoming years unless preventive actions are taken. Many studies have addressed...

A recent UN report has shown that the construction industry is one of the seven major sectors that contribute significantly to environmental pollution and was responsible for around 20% of energy-related CO2 emissions in 2020, and this is expected to increase during the upcoming years unless preventive actions are taken. Many studies have addressed...

Faced with a climate emergency, civil engineers need to start reducing, reusing and repurposing now. But the profession first needs to debunk its sustainability myths, say James Norman of the University of Bristol, Tim Ibell of the University of Bath and Oliver Broadbent of Constructivist.

A recent UN report has shown that the construction industry is one of the seven major sectors that contribute significantly to environmental pollution and was responsible for around 20% of energy-related CO2 emissions in 2020, and this is expected to increase during the upcoming years unless preventive actions are taken (UN Environment program, 202...

This paper seeks to establish the current state of research into adaptive building reuse with the view to highlighting new approaches and opportunities for expanding the collective knowledge on this subject. This approach focuses on appraisal and evaluation of current methods by looking through a structural engineering lens and considering the most...

This paper presents a new methodology for cost- and carbon-optimal generation of multi-storey building designs. The methodology features algorithms for automatic optimised design of concrete, steel, and timber frames; established as well as novel decking technologies; and foundation options. Applying the methodology, we illustrate the potential car...

The present climate emergency demands the construction industry to minimise the carbon footprint of concrete buildings. In this paper, the potential different optimisation strategies to reduce ‘cradle-to-gate’ embodied carbon of concrete floors which require different levels of modifications to the conventional design and construction practice were...

Minimising carbon emissions from the building construction industry is of paramount importance in the present context due to the rising concerns of climate change. This paper explores the potential of minimising embodied carbon in reinforced concrete flat slabs by parametrically varying the slab thickness, grade of concrete, column spacing, column...

A significant number of studies have addressed the environmental footprint of superstructures, however , the environmental footprint of substructures has only been investigated to a limited extent. This research focuses on the environmental impact of deep foundations and means of minimising their embodied carbon. An analytical model is used to exam...

Minimising the carbon footprint of concrete buildings is vital in the presence of the climate emergency. In this paper, a framework to reduce the embodied carbon of concrete floors with the resources available at the market and adopting cutting-edge construction methods are investigated in a progressive approach. Starting from conventional reinforc...

Multi-objective optimisation of concrete floors for economic and environmental performance is critical in the present context since the building construction sector is responsible for a rising share of the global economy and greenhouse gas emissions. This study explores how the designs with optimum cost and embodied carbon are governed by the selec...

The construction industry has received attention due to its significant contribution to global carbon emissions. In this paper, conventional design and construction practices of reinforced concrete beams are scrutinised to explore the potential for reductions in embodied carbon. For a given set of design criteria, a family of discrete beam designs...

Decarbonisation of the energy industry and enforcement of strict targets for operational energy consumption means that non-operational greenhouse gases (GHG) emissions, also known as embodied carbon (EC), will soon represent the majority of whole life carbon associated with buildings. EC assessments are often presented as deterministic, single-poin...

The enormous environmental impact of construction is becoming increasingly apparent and unacceptable to many structural engineers, whose designs typically account for the majority of a building's embodied carbon. It is timely, therefore, that consensus is forming around a methodology for calculating embodied carbon. This encourages the inclusion of...

The construction industry is responsible for nearly half of the UK’s carbon emissions, mainly due to the large amount of concrete used. Traditional formwork methods for concrete result in prismatic building elements with a constant cross-section, but the shear forces and bending moments that beams have to withstand are far from constant along their...

James Norman, Tim Ibell and Oliver Broadbent examine the challenges engineers will face in persuading clients to repurpose existing buildings in place of building new ones.

Tim Ibell, James Norman and Oliver Broadbent challenge structural engineers to steer their clients away from a presumption of a new building.

A combination of flexible moulds as external formwork and bespoke robotically fabricated fibre reinforced polymer cages as tensile reinforcement offers a new opportunity for the manufacture of structural concrete components that have been optimised to minimise material use. This technology could potentially help in our quest to reduce carbon emissi...

This paper explores the potential of thin concrete shells as low-carbon alternatives to floor slabs and beams, which typically make up the majority of structural material in multi-storey buildings. A simple and practical system is proposed, featuring precast textile reinforced concrete shells with a network of prestressed steel tension ties. A non-...

We can’t wait for breakthrough technologies to deliver net-zero emissions by 2050. Instead, we can plan to respond to climate change using today’s technologies with incremental change. This will reveal many opportunities for growth but requires a public discussion about future lifestyles.

Interest in the shape optimisation of concrete members is increasing alongside the availability of fabric formwork as a relatively simple technique to cast non-prismatic concrete structures. Research has shown that up 40% of concrete can be saved when shape optimised concrete beams are cast in fabric forms. However, optimisation results in members...

There is no reason why concrete elements should be prismatic. Concrete is mouldable and can be cast in efficient forms which follow the stresses varying along the length of a concrete element. One option to achieve this is to use fabric as flexible formwork. Fabric deforms under the hydrostatic pressure exerted by wet concrete during construction,...

The built environment accounts for 39% of global energy related CO2 emissions, and construction generates 13% of global GDP. Recent success in reducing operational energy and the introduction of strict targets for near-zero energy buildings mean that embodied energy is becoming the dominant component of whole life energy consumption in buildings. O...

Rapid global urbanisation and population growth is driving unprecedented levels of building construction, with the total worldwide floor area expected to almost double over the next 40 years. Since most of the structural material in a building exists within the floors, these present a significant opportunity for structural engineers to contribute t...

A new report that details the results of a survey of structural engineering practitioners that examined both culture and practice in design relating to material efficiency, undertaken as part of the EPSRC funded project “Minimising Energy in Construction” (MEICON) led by Dr John Orr. The first MEICON report is the beginning of a conversation. As...

Buildings are being constructed at ever faster rates, fuelled by population growth and urbanisation. The total worldwide floor area of buildings is expected to almost double over the next 40 years, the equivalent of constructing Paris every five days [1]. The majority of the mass and embodied energy (60% to 70%) in a typical multi-storey building s...

A reduction in ductility after applying fiber-reinforced polymer (FRP) materials to strengthen existing reinforced concrete (RC) structures has been reported in previous research. Consequently, design standards worldwide employ cautious guidance for the design of FRP strengthening systems, which limits the exploitation of moment redistribution in c...

Shells have the potential to considerably reduce material consumption in buildings due to their high structural efficiency compared to equivalent structures acting in bending. Textile reinforced concrete (TRC) is a promising material for the construction of thin concrete shells due to its strength, geometric versatility, and durability. Existing de...

Shells have the potential to considerably reduce material consumption in buildings due to their high structural efficiency compared to equivalent structures acting in bending. Textile reinforced concrete (TRC) is a promising material for the construction of thin concrete shells due to its strength, geometric versatility, and durability. Existing de...

With the goal of achieving sustainable design, being able to combine optimized geometries with durable construction materials is a major challenge for Civil Engineering. Recent research at the University of Bath has demonstrated that fibre-reinforced polymers (FRP) can be woven into geometrically appropriate cages for the reinforcement of optimised...

This project has made progress towards the development of a novel alternative reinforcement technique for concrete structures with complex geometries, which are difficult to reinforce with conventional steel. Fibre-reinforced polymers (FRP) are woven into geometrically appropriate reinforcement cages to provide the required strength exactly where i...

The findings of a durability study undertaken on pultruded glass fibre reinforced polymer (GFRP) cladding panels are presented. Sourced at demolition from the Second Severn Crossing Visitors' Centre building in the UK, the panels offered the rare opportunity to assess the characteristics of naturally aged composite material. Mechanical properties w...

Steel-reinforced concrete, cast in flat prismatic forms, dominates multi-storey building construction around the world. Despite the fluidity of the material, opportunities to create efficient geometries through manipulation of form are habitually overlooked, resulting in inefficient cracked sections, high steel requirements and large carbon footpri...

The Deep Embedment (DE) or Embedded Through Section (ETS) technique is a new retrofit method to increase the shear capacity of reinforced concrete (RC) structures using fibre-reinforced polymer (FRP) or steel bars. Following the development of this technique, the structural behaviour of RC continuous beams strengthened with the DE method needs to b...

The periodic assessment of our existing concrete infrastructure is a crucial part of maintaining appropriate levels of public safety over long periods of time. It is important that realistic predictions of the capacity of existing structures can be made in order to avoid unnecessary and expensive intervention work. Assessment is currently undertake...

Spike anchors are a promising way to enhance the maximum capacity and post-peak load-strain response of externally-bonded fibre-reinforced polymer (FRP) materials for retrofitting of concrete structures. Although laboratory testing has proven the effectiveness of these spike anchors (also known as fan anchors), little work has been conducted to pro...

The periodic assessment of our existing concrete infrastructure is a crucial part of maintaining appropriate levels of public safety over long periods of time. It is important that realistic predictions of the capacity of existing structures can be made in order to avoid unnecessary and expensive intervention work. Assessment is currently undertake...

Spike anchors are a promising way to enhance the maximum capacity and post-peak load-strain response of externally-bonded fibre-reinforced polymer (FRP) materials for retrofitting of concrete structures. Although laboratory testing has proven the effectiveness of these spike anchors (also known as fan anchors), little work has been conducted to pro...

This project brings together modern developments in computational design, materials and construction methods to propose a novel thin-shell concrete flooring system for multi-storey buildings, aiming to create a low embodied energy and lightweight alternative to traditional reinforced concrete flat slabs.

The Deep Embedment (DE) technique is an innovative shear-enhancement retrofit technique for concrete structures that requires introduction of Fibre-Reinforced Polymer (FRP) or Steel bars upwards into vertical or inclined holes which have been drilled through the beam section. An experimental campaign consisting of ten two-span continuous reinforced...

The Deep Embedment (DE) of Fibre-Reinforced Polymer (FRP) or steel bars is a shear-enhancement retrofit technique for concrete structures. This technique requires introduction of FRP or Steel bars upwards into vertical or inclined holes which have been drilled through the beam section. To test the DE technique an experiment which incorporated ten t...

The built environment is materially inefficient, with structural material wastage in the order of 50% being common. As operational energy consumption in buildings falls, due to continued tightening of regulations and improvements in the efficiency of energy generation and distribution, present inefficiencies in embodied energy use become increasing...

The built environment is materially inefficient, with structural material wastage in the order of 50% being common. As operational energy consumption in buildings falls, due to continued tightening of regulations and improvements in the efficiency of energy generation and distribution, present inefficiencies in embodied energy use become increasing...

Because of the premature debonding of fiber-reinforced polymer (FRP) materials that results in a reduction in ductility, the problem of how to exploit moment redistribution (MR) in FRP-strengthened continuous reinforced concrete (RC) structures is unresolved. To date, limited research has been conducted into MR in such structures; a reliable and ri...

The findings of a durability study undertaken on pultruded glass fibre reinforced polymer (GFRP) cladding panels are presented. Sourced at demolition from the Second Severn Crossing Visitors’ Centre building in the UK, the panels offered the rare opportunity to assess the characteristics of naturally aged composite material. Mechanical properties w...

Despite numerous studies, shear behaviour before or after strengthening is still not fully understood, particularly in continuous concrete structures which are the norm. Upgrading shear resistance is altogether more difficult since Externally Bonded Reinforcement (EBR) or Near Surface Mounted (NSM) techniques do not allow the FRP material to be anc...

Concrete is the most widely used construction material. Worldwide consumption of cement, the strength‐giving component in concrete, is now estimated to be 4.10 Gt per year, having risen from 2.22 Gt just 10 years ago. This rate of consumption means that cement manufacture alone is estimated to account for 5.2 % of global carbon dioxide emissions. C...

This paper presents data from a number of experiments carried out to measure the rate with which the force from an impact propagates from hard impacts on reinforced concrete members. It has been demonstrated that a finite, measurable time exists between a concentrated impact occurring and the force being experienced at the supports. The data presen...

Consideration of moment redistribution (MR) in the design of continuous reinforced concrete (RC) beams results in an efficient and economical design. Adding fibre-reinforced polymer (FRP) materials to reinforced structures to enhance flexural capacity leads to a reduction in ductility, such that design standards severely limit use of the MR in thei...

In this paper, the durability of fabric formwork-based concrete made from supersulfated cement was studied. The study involved comparison of chloride and carbonation resistance, pH values, and water absorption between of surfaces of SSC, the one being cast and the other cast in fabric formwork. It was shown that the use of fabric formwork minimized...

Fabric formwork is a novel concrete construction method which replaces conventional prismatic moulds with lightweight, high strength sheets of fabric. The geometry of fabric formed structures is therefore dictated by the behaviour of fabric under hydrostatic loading. While there are numerous examples of digital and physical modelling of this proble...

The main focus of this study is to significantly contribute to the current knowledge on the behav-iour of RC continuous T-beams strengthened in shear using the Deep Embedment (DE) technique where large shear forces are combined with large negative bending moments. For this purpose an experimental program consisting of ten two-span continuous T-beam...

An experimental investigation was undertaken into the effectiveness of unanchored and anchored externally bonded (EB) U-wrapped carbon fibre reinforced polymer (CFRP) shear strengthening for reinforced concrete T-beams at a range of realistic sizes. The T-beam sizes, geometry and reinforcement were chosen to reflect existing slab-on-beam structures...

This paper details a new numerical method for determining the form of a section of flexible, impermeable and inextensible hanging fabric subject to the hydrostatic load imposed by wet concrete. A closed form solution is already known to exist in the form of incomplete elliptic integrals, but this can be difficult to implement in practice. The numer...

Because of the premature debonding of fiber-reinforced polymer (FRP) materials that results in a reduction in ductility, the problem of how to exploit moment redistribution (MR) in FRP-strengthened continuous reinforced concrete (RC) structures is unresolved. To date, limited research has been conducted into MR in such structures; a reliable and ri...

Consideration of moment redistribution (MR) in the design of continuous reinforced concrete (RC) beams results in an efficient and economical design. Adding fibre-reinforced polymer (FRP) materials to reinforced structures to enhance flexural capacity leads to a reduction in ductility, such that design standards severely limit use of the MR in thei...

Fabric form-work is a technique to cast concrete structures with a great advantage of saving concrete material of up to 40%. This technique is particularly associated with the optimized concrete structures that usually have smaller cross-section dimensions than equivalent prismatic members. However, this can make the structural system produced from...

A linear elastic analytical model of curved beam with constant curvature coupled with curved strings has been developed. To model the connections between the strings and the beam, a continuous distribution of tangential and orthogonal linear elastic springs have been introduced. To evaluate the behavior of the system, a numerical integration of the...

The Author(s) 2016 Reprints and permissions. A linear elastic analytical model of curved beam with constant curvature coupled with curved strings has been developed. To model the connections between the strings and the beam, a continuous distribution of tangential and orthogonal linear elastic springs have been introduced. To evaluate the behavior...