Robert Hertle

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Armando Marques-Guedes

UNL - New University of Lisbon

Iolanda Craifaleanu

Technical University Of Civil Engineering, Bucharest

Fabián Hoyos Patiño

Universidad Nacional de Colombia (National University of Colombia)

Angel Berenguer

University of Alicante / Universidad de Alicante

Kenneth Vecchio

University of California, San Diego

Roberto Cortes

University of the Basque Country, Euskal Herriko Unibertsitatea

Isidro Martínez Mira

University of Alicante / Universidad de Alicante

William Rodriguez Serquen

Universidad Nacional Pedro Ruiz Gallo

Engr Sajid Chaudhary

University of Gujrat

mahmoud hafiz

Al-Azhar University

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Papers by Robert Hertle

Gerüstbau

Wiley-VCH Verlag GmbH eBooks, Apr 14, 2014

Strengthening of a City Center Tunnel with Concrete Screw Anchors under Special Boundary Conditions

Report, 2019

The Altstadtring-Tunnel is one of the essential east-west traffic routes in the city center of Mu... more The Altstadtring-Tunnel is one of the essential east-west traffic routes in the city center of Munich and was constructed in the late 1960s. Segment 34 of the tunnel was built directly underneath the existing Prince-Carl- Palais, a historic building from 1804. Therefore 15 pre-stressed concrete girders with an effective depth of3.5 m and a maximum span of up to 30 m were built which now form the tunnel roof slab. These girders were pre-stressed with steel nowadays well known for stress corrosion cracking. A recalculation of the slab showed that no ductile failure can be guaranteed in case of a progressive rupture of the tendons. Therefore, a concept for strengthening the slab was developed using concrete screw anchors as post installed bending and shear reinforcement. The concrete screw anchors are normally installed as anchoring elements in cracked and non- cracked concrete and are available with diameters up to 22 mm. Developing this concept further, it is straight forward to use these anchoring elements as post-installed reinforcement in existing concrete structures. This new strengthening system was developed at the University of Innsbruck in the last few years and can fulfill the special requirements of this project, such as installation of the strengthening system from underneath the tunnel slab during ongoing use of the structure. High strength steel with diameters of up to 63.5 mm will be used as post-installed bending reinforcement covered with a new shotcrete layer on the underside of the tunnel slab. In total 59.3 tons of new flexural reinforcement and 7199 concrete screws for strengthening the shear capacity of the girders will be used to ensure a ductile failure of the tunnel slab. The on-site work started in March 2019 and is expected to take two years to complete.

Practical Examples of Successful Design Review

Report, 2019

is a consultant and design review engineer spezialised in infrastructure and industrial plant str... more

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Aerodynamische Anregung von Schutzwandkonstruktionen an schienengebundenen Hochgeschwindigkeitsstrecken / Aerodynamic excitation on protection-shield-constructions along high-speed-railway-tracks

Bauingenieur, 2005

Bemessung und Konstruktion von Schallschutzwand- und Windschutzwandkonstruktionen an schienengebu... more Bemessung und Konstruktion von Schallschutzwand- und Windschutzwandkonstruktionen an schienengebundenen Hochgeschwindigkeitsstrecken werden hinsichtlich der Betriebsfestigkeit durch die aerodynamische Anregung infolge Zugvorbeifahrten bestimmt. Im vorliegenden Beitrag wird ueber die Entwicklung eines fuer analytische Untersuchungen geeigneten Lastbilds fuer Schutzwandkonstruktionen auf der Grundlage umfangreicher Messungen und ueber die Ergebnisse einer dynamischen Analyse des Gesamtsystems einer Schutzwandkonstruktion sowie deren einzelner Bauteile berichtet. Die Herleitung von bauteilspezifischen Schock-Spektren erlaubt die Ableitung von Konstruktionsempfehlungen fuer derartige Bauwerke. (A) ABSTRACT IN ENGLISH: Design and calculation of noise-protection- and wind-protection-shield-constructions along high-speed-railway-tracks are defined with the respect to fatigue by the aerodynamic excitation induced by trains. In the present paper information on the development of a synthetic load-pattern for protection-shield-constructions on the base of numerous measurements, and on the results of dynamic analyses of the global system and of the single components are given. The derivation of component-shock-spectra gives inside views on the mechanical properties of such types of constructions and forms the base for design recommendations. (A)

Particular stability aspects of temporary structures

IABSE Congress Report, 2016

When analysing the stability of temporary works equipment some structural peculiarities like the ... more When analysing the stability of temporary works equipment some structural peculiarities like the easy to erect, easy to dismantle character of the structure, the influence of shear stiffness on the deformation behaviour, not negligible eccentricities both concerning the load application and within the structural system, semi-rigid joints, the structure-to-structure interaction or the repeat- ed use with loads often touching or even exceeding the characteristic values have to be consid- ered. This paper exemplifies the structural design´s consequences of these peculiarities. Particular emphasis is laid on the interaction between temporary works equipment´s design and production principles, the on-site boundary conditions, the technical and economical restrains and the there- from resulting consequences for the responsible designer.

Challenges when enhancing the infrastructure – case studies

IABSE Congress Report, 2021

The fundamental rational of the German way to ensure structural safety and to prevent the society... more The fundamental rational of the German way to ensure structural safety and to prevent the society from undue harm is independent design review and execution supervision. This paper will explain both regarding the way in which review and supervision are performed, as well as the qualification needed for the design and supervision review engineer, who acts as a trustee of the public administration. The development of the review and supervision regime and of the underlying set of technical rules and regulations will be addressed by discussing actual and historic case studies. Special emphasis will be put on the interface-problems when different parties are involved and on the necessity of good and reliable coordination mechanisms between the involved parties. As a consequence of the increasing fragmentation of the design process in combination with the use of complex software tools and inevitable time pressure often the integrated design review process is the last line of defence to avoid incidents due to minor lapses or serious misjudgements.

Enhancement of structural safety by safety factors – a case against the common approach

IABSE Congress Report, 2021

In every available structural design code, safety concepts, which account for uncertainties in th... more In every available structural design code, safety concepts, which account for uncertainties in the design, are defined. The safety factors underlying these concepts vary strongly in their magnitude and application - one can find partial safety factors, which exhibit different values for load actions and resistances, as well as global safety factors, which are applied either on load actions, when geometrical non-linearities are prevailing, or on the structure’s resistances, when a straightforward linear determination of the forces and moments acting within the structure is sufficient. The values of the safety factors have been derived traditionally by experience before probabilistic approaches, that attempt to cover every significant epistemic and aleatory uncertainty in the design, were available. By application of stochastic methods, the objective is and was the derivation of optimal safety factors. The derived values of safety factors are subject of many discussions within the professional and scientific community, since they can shift market shares of different construction methods and materials significantly or make structural verification of existing structures impossible. The latter mentioned argument is especially valid when dealing with existing, often decades or centuries old, structures. Sometimes, the safety factors are even used to exclude certain materials from the market. However, the importance of such factors should be questioned [1]. When analysing the reasons for structural failures, widespread research show that the massively larger share of failures is associated with human error, which is, due to its very nature, not covered by safety factors. To explain the antagonism between safety factors solely relying on a probabilistic approach and the nature of human error, corresponding examples will be discussed, the corresponding probabilities of failure will be assessed and the consequences on future structural design rules will be highlighted in this paper.

Challenges towards Design Review due to Cultural and Human Factors

Report, 2019

Design review has proven effective to avoid human errors in the design process. Since human error... more Design review has proven effective to avoid human errors in the design process. Since human error is the major cause for structural collapse [1], most countries have implemented procedures for design review in their building legislation. These systems represent the lived building culture in each state and thus work differently. Within the European harmonization process, challenges regarding the integration of different building cultureshave been discovered. These cultural challenges affect structural safety in a wide array of topics, e.g. technicalapproval of building products.In this paper, the effect of differences in the building culture and the way they affect structural safety will be investigated. Furthermore, the effect on the individual due to human factors will be examined and assessed. The goal is to provide a better understanding of the impact of cultural differences on the design review procedure and on the individual.

A Critical Assessment of the Fatigue Verification Concept of Stud Shear Connectors in Steel- Concrete-Composite Members for Bridges

Report, 2018

Stud shear connectors in steel-concrete-composite structures transfer the stresses from one compo... more Stud shear connectors in steel-concrete-composite structures transfer the stresses from one composite layer to the adjacent one and thus represent vital elements for the load-bearing capacity of the structural member under consideration. In bridge structures, the fatigue strength of the stud shear connectors, which are welded onto a steel member, is especially important. Verification concepts for the fatigue strength have been developed and implemented in design codes, such as EN 1994 [1]. These design concepts generally focus on the verification of the steel while the interaction of steel and concrete, resulting in flexure of the stud shear connector and in extreme, locally confined concrete pressure, is considered only by indirect means, if at all. Studies (see [2] and [3]) showed this influence to be substantial. The verification concepts provided by design codes focus on the shear-stress-range and the corresponding number of load cycles until fatigue failure occurs. These procedures neglect the amplitude and mean stress level of the concrete, which have been proven to have significant influence on the fatigue strength [4]. This paper will analyse and explain available verification concepts. Shortcomings will be discussed and an improved approach to the S-N curve for the verification of the stud shear connectors will be presented.

A Critical Take on Eurocode 2 Concerning the Assessment of Shear Capacity of Reinforced and Prestressed Concrete

Report, 2017

Most of the infrastructure in Europe dates back to the midst of the 20th century. In recent years... more Most of the infrastructure in Europe dates back to the midst of the 20th century. In recent years it became more and more important to conserve and revamp this existing network of traffic roads and bridges to meet the actual and future requirements of the society. With the introduction of the DIN 1045-1 in 2001 and the actual generation of the Eurocodes in 2012-2013 the re-evaluation of existing structures, i.e. especially bridges, became more difficult when using these technical rules as a base. In many cases the new calculations resulted in a significant smaller load-bearing capacity than the constructions were designed for back in the day. In particular, re-evaluations of the shear capacity of these structures show big discrepancies between the amount of steel that is needed depending on the old regulations or the new Eurocodes. These discrepancies are shown by typical examples and possible ways to handle the results will be discussed. By looking at advanced shear models and non-linear finite element calculations possible further developments of the shear-limit- state formulation are suggested.

Checking of Structural Safety – Experiences with Large-Scale Structures

IABSE Congress Report, 2016

Safeguarding the structural integrity and hence preventing the people from undue hazards is an el... more Safeguarding the structural integrity and hence preventing the people from undue hazards is an elementary task of a society. The peculiarities of structural engineering make it impossible to hark back to quality management systems well known from industrial production processes. The proto- type-design typical for civil engineering structures requires different as well as enhanced strate- gies. By discussing three large scale projects, the German approach to this task will be explained. Emphasis is laid especially on the technical and economic independence of the reviewing process.

An Empricially Verified System for Quality and Risk Management

IABSE Congress Report, 2016

From experience with structural failures, one can see that human error, in design and execution, ... more From experience with structural failures, one can see that human error, in design and execution, is the major cause for these incidents. However, human error is not covered by any approach to structural reliability. Therefore, a system for quality and risk management is required that accounts for human error. Such systems are mostly organized on a national level and exhibit significant differences.This paper compares corresponding international approaches on how to handle human error and evaluates them.A proposal for an adequate quality and risk management system covering human error will be presented. The proposal will be composed of the best parts of several available systems to provide an empirically verified, widely accepted approach.

Influences on Determining Structural Reliability

Report, 2017

The influences to investigate when trying to assess the reliability of structures are manifold. E... more The influences to investigate when trying to assess the reliability of structures are manifold. Even if all the relevant stochastic parameters and data for establishing a typical reliability model are known, there are uncertainties to be considered which cannot be covered by probabilistic methods only. In a probabilistic analysis, the basic variables of a design problem, such as e.g. material strength or load effects, have to be modelled as random variables. From there, the failure probability of a mem- ber can be determined by use of methods of reliability analysis.This relatively straightforward procedure reaches its limits when additional influences like the sim- plification and/or linearization of the design problem, the model-reality-antagonism, the paper- building site transformation or human error are to be considered. Especially the three latter are not tangible by stochastic methods only. As the nature of these issues is predominantly human, individ- ual competence or its opposite deprive a purely mathematical approach to achieving sufficient reli- ability.

Special aspects concerning the incremental launching of one composite bridge

Influence of the Design Review Process on the Structural Design Engineer due to Human Factors

Report, 2018

It is common sense, that human error is the major cause for structural collapse [1]. Design revie... more It is common sense, that human error is the major cause for structural collapse [1]. Design review is the most effective way to rid human errors out of the design process and thus most societies have procedures for the design review installed. These systems work differently, e.g. preventive or repressive, and consequently affect the involved parties differently.In this paper, the effect of different design review systems on the engineer as an individual will be assessed by addressing human factors that influence design decisions. The paper will focus on the structural design engineer, the effects on other included parties will be assessed in following studies.The goal is to provide a better understanding of the impact of the design review procedure on the individual. Human factors affect the design engineer subconsciously and influence the decision- making in a significant way. Awareness of these factors and the corresponding influence due to the design review system will improve the design outcome and the relationship of design engineer and design review engineer.

Influence of Human Error on Structural Reliability

Report, 2017

In common structural design, random variables, such as material strength or loads, are represente... more In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Building Facility Development – The Renewal of a Car Plant without interfering the Production

Future development of production sites in the motor industry require an integrated approach for d... more Future development of production sites in the motor industry require an integrated approach for design and realization of the building construction works as well as coordination with the production process to find on one side a feasible solution for the building construction and to allow on the other side minimized disturbance of the plant production output. If the plant is located in the inner districts of a city, the task will be complicated by taking the boundary conditions of the adjacent areas into account. To develop the answer which fits the needs of the plant management best, it is necessary to start the basic design considerations with a survey of the existing building, sufficiently deep to elaborate all necessary information, especially concerning material qualities, geometrical dimensions, actual loading conditions etc. Based on these, the structural concept chosen has to go beyond the usual measures taken in many aspects. For example techniques like incremental launching, well known from bridge construction, soil improvement by jet-grouting, the application of mono-piles for transferring the loads to deeper situated soil-layers or gluing for the application of strengthening elements are used. Another aspect of the design exercise follows from fire-resistance considerations. Modified regulations or/and a changed profile of use may yield to a new assessment of the structural qualities when exposed to fire.

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Scheibenschub und Plattenbiegung bei der Bemessung des Stahlbetongurts von Verbundträgern

Stahlbau, May 1, 2005

Die Bemessung der Gurtplatten von Stahlverbundträgern unter kombinierter Beanspruchung infolge Sc... more Die Bemessung der Gurtplatten von Stahlverbundträgern unter kombinierter Beanspruchung infolge Scheibenschub und Plattenbiegung wird im technischen Regelwerk für Stahlverbund‐ und für Stahlbetonbauteile durch eine einfache Überlagerungsvorschrift, welche auf die Ergebnisse einer Analyse der jeweiligen Einzelschnittgrößen Scheibenschub respektive Plattenbiegung abstellt, behandelt. Vor dem Hintergrund einer Bemessung der Verbundträger unter Rückgriff auf plastizitätstheoretische Ansätze zur globalen und zur lokalen Schnittgrößenverteilung kann es, um die Gültigkeit dieser Überlagerungsvorschrift auch für diese Modellierung zu verifizieren, erforderlich werden, den tatsächlich vorhandenen kombinierten Beanspruchungszustand in der Gurtplatte zu erfassen. Hierzu ist eine Beschreibung des Beanspruchungszustands in der Gurtplatte, welche die Abtragung der Schub‐ und der Biegedruckkräfte über räumlich geneigte Druckstreben abbildet, geeignet.

Gerüstbau - Stabilität und statisch-konstruktive Aspekte

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jul 22, 2009

Failure Identification: Procedural Causes and Corresponding Responsibilities

Structural Engineering International, Aug 1, 2017

When structural members fail, there must be a physical cause, such as missing reinforcement or fa... more When structural members fail, there must be a physical cause, such as missing reinforcement or failing supports. The physical cause itself is often triggered by deficits in the design, in the execution and in the chosen reliability management procedures. Consequently, these deficits determine the level of responsibility for the failure of the involved parties. Human error generally plays a major role in the development of procedural issues; thus, the focus of avoidance in a reliability management system is of special importance. This paper defines the relevant aspects of a reliability management system, introduces practical examples of failure investigations and outlines the related measures to avoid human error that may have contributed to the failure.

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Gerüstbau

Wiley-VCH Verlag GmbH eBooks, Apr 14, 2014

Strengthening of a City Center Tunnel with Concrete Screw Anchors under Special Boundary Conditions

Report, 2019

Practical Examples of Successful Design Review

Report, 2019

is a consultant and design review engineer spezialised in infrastructure and industrial plant str... more

Download

Aerodynamische Anregung von Schutzwandkonstruktionen an schienengebundenen Hochgeschwindigkeitsstrecken / Aerodynamic excitation on protection-shield-constructions along high-speed-railway-tracks

Bauingenieur, 2005

Particular stability aspects of temporary structures

IABSE Congress Report, 2016

Challenges when enhancing the infrastructure – case studies

IABSE Congress Report, 2021

Enhancement of structural safety by safety factors – a case against the common approach

IABSE Congress Report, 2021

Challenges towards Design Review due to Cultural and Human Factors

Report, 2019

A Critical Assessment of the Fatigue Verification Concept of Stud Shear Connectors in Steel- Concrete-Composite Members for Bridges

Report, 2018

A Critical Take on Eurocode 2 Concerning the Assessment of Shear Capacity of Reinforced and Prestressed Concrete

Report, 2017

Checking of Structural Safety – Experiences with Large-Scale Structures

IABSE Congress Report, 2016

An Empricially Verified System for Quality and Risk Management

IABSE Congress Report, 2016

Influences on Determining Structural Reliability

Report, 2017

Special aspects concerning the incremental launching of one composite bridge

Influence of the Design Review Process on the Structural Design Engineer due to Human Factors

Report, 2018

Influence of Human Error on Structural Reliability

Report, 2017

Building Facility Development – The Renewal of a Car Plant without interfering the Production

Download

Scheibenschub und Plattenbiegung bei der Bemessung des Stahlbetongurts von Verbundträgern

Stahlbau, May 1, 2005

Gerüstbau - Stabilität und statisch-konstruktive Aspekte

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jul 22, 2009

Failure Identification: Procedural Causes and Corresponding Responsibilities

Structural Engineering International, Aug 1, 2017

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