Innovation zur Bestimmung der Erdstoff‐Geokunststoff‐Wechselwirkung – Pullout‐, Scher‐ und Reibungsversuche

Innovation for the determination of the soil‐geosynthetic interaction – pullout‐, shear‐ and friction tests. The use of the economical and ecological construction material “geosynthetic” plays a rapidly increasing role in a variety of civil engineering, mining and environmental protection applications. Geosynthetics captured their own place as construction material due to their diversity and their specific characteristics. The applications of geosynthetics are many‐sided. In the form of geotextiles, geogrids, geomembranes and related products, they make technically simple and low‐priced alternative solution concepts possible. For the stability analysis of geosynthetic constructions knowledge of the friction behaviour in the geosynthetic interfaces is essential. For the assessment of the main failure mechanisms of a geosynthetic reinforced construction shear‐ and friction tests are usually performed as well as now also Pullout tests. In the following, a novel experimental apparatus for the examination of the interaction behaviour of soil‐geosynthetic compound systems capable of performing both pullout and direct shear tests is described. In comparison with known geosynthetic testing practice, the novel testing apparatus offers the special advantage that a wide range of innovative shear and pullout test procedures can be carried out in the same device with negligible influence of test device configurations on friction test results.     

A Two‐Dimensional Plum‐Blossom Sensor Array‐Based Multiple Signal Classification Method for Impact Localization in Composite Structures

The growing use of composite materials on aircraft structures has attracted much attention for the impact monitoring as a kind of structural health monitoring method. Uniform linear sensor array (ULSA)‐based multiple signal classification (MUSIC) technology is a promising method because of its directional scanning ability and easy arrangement of the sensor array. However, the monitoring range of ULSA‐based MUSIC method is 0°–180°, and its beamforming properties degrade at angles close to 0° and 180°. Besides, the ULSA‐based MUSIC methods proposed require the knowledge of the direction dependent velocity profile obtained by additional experiments. This article presents a novel two‐dimensional (2‐D) plum‐blossom sensor array (PBSA)‐based MUSIC method. First, the velocity propagating at the specific direction is estimated by impact signal itself using PBSA directly. Second, 2‐D PBSA‐based MUSIC method well realizes omnidirectional 0°–360° impact localization of composite structures. Experimental results show its successful performance on epoxy laminate plate and complex composite structure.     

Forward‐Backward Approach for 3D Event Localization Using Commodity Smartphones for Ubiquitous Context‐Aware Applications in Civil and Infrastructure Engineering

An inexpensive and robust 3D localization system for tracking the position of a user in GPS‐ or WLAN‐denied environments offers significant potential for improving decision‐making tasks for civil and infrastructure engineering applications. To this end, an infrastructure‐free approach for 3D event localization on commodity smartphones is presented. In the proposed method, the position of the user is continuously tracked based on the smartphone sensory data (the Forward approach) until the user reaches a certain event. Here, an event location refers to the 3D location of a user conducting value‐added activities such as tasks involved in emergency response and field reporting of operational issues. Once an event is observed, the motion trajectory of the user is backtracked from the postevent landmark to reestimate the location of the event (the Backward approach). By integrating probability distributions of the Forward and Backward approaches together, the proposed method derives the most‐likely location of the event. To validate the proposed approach, seven case studies are conducted in a multistory parking garage. The experimental results show that the probabilistic integration of the localization results from the Forward and Backward dead reckonings can produce more accurate 3D localization results when compared to a single best estimate from a one‐way dead reckoning process. Lessons learned from several real‐world case studies and open research challenges in improving localization accuracy are discussed in detail.     

Stahlglas‐Bauweise – an einer Treppe werden neue Perspektiven im Konstruktiven Glasbau sichtbar

A self‐supporting glass staircase. This staircase is unique in regard to its span and loading capacity so far, was shown at the fair “Glasstec 2004”. Structural engineers are stretched by ambitious load‐bearing structures of glass in two ways. With the material‐appropriate design and the construction of the details of the structure, creativity and profound knowledge of the behaviour of the material and the load‐bearing structure are demanded by them. Well founded knowledge is required to make the load‐bearing structures sufficiently safe and as economic as possible, because there are no design standards. This article reports on the construction and production of the staircase built in a method of construction called “reinforced glass” (termed according to its load carrying effect – compare with “reinforced concrete”). It starts with an abstract of this method of construction including the safety concept, which has been developed at the University of Technology of Hamburg‐Harburg. The proof of the structural safety, for which loading experiments were required as well, will soon be treated in this magazine.     

Unified Vision‐Based Methodology for Simultaneous Concrete Defect Detection and Geolocalization

Vision‐based autonomous inspection of concrete surface defects is crucial for efficient maintenance and rehabilitation of infrastructures and has become a research hot spot. However, most existing vision‐based inspection methods mainly focus on detecting one kind of defect in nearly uniform testing background where defects are relatively large and easily recognizable. But in the real‐world scenarios, multiple types of defects often occur simultaneously. And most of them occupy only small fractions of inspection images and are swamped in cluttered background, which easily leads to missed and false detections. In addition, the majority of the previous researches only focus on detecting defects but few of them pay attention to the geolocalization problem, which is indispensable for timely performing repair, protection, or reinforcement works. And most of them rely heavily on GPS for tracking the locations of the defects. However, this method is sometimes unreliable within infrastructures where the GPS signals are easily blocked, which causes a dramatic increase in searching costs. To address these limitations, we present a unified and purely vision‐based method denoted as defects detection and localization network, which can detect and classify various typical types of defects under challenging conditions while simultaneously geolocating the defects without requiring external localization sensors. We design a supervised deep convolutional neural network and propose novel training methods to optimize its performance on specific tasks. Extensive experiments show that the proposed method is effective with a detection accuracy of 80.7% and a localization accuracy of 86% at 0.41 s per image (at a scale of 1,200 pixels in the field test experiment), which is ideal for integration within intelligent autonomous inspection systems to provide support for practical applications.     

RFID Enabled Knowledge‐Based Precast Construction Supply Chain

Radio frequency identification (RFID) helps improve supply chain efficiency by providing item‐level identification and real‐time information. Today, barcode continues to be the main identification technology for precast construction applications. In this research, we investigate the data‐driven mechanisms and benefits of utilizing RFID in knowledge‐based precast construction supply chains. With computer‐aided self‐learning capability, we simulate three models for manual‐, barcode‐, and RFID‐enabled precast construction supply chain. The results of 100 precast wall‐panel construction in a two‐echelon precast construction supply chain reveal that the knowledge‐based RFID system could generate 62.0% saving of operational costs, which is 29.0% higher than that of a barcode‐based system. As a result, the computer‐aided adaptive learning mechanism based on RFID is verifiable to improve the overall operational performance by reducing lead time, operational errors, and costs. Due to the lack of existing literature of data technology utilization in the precast construction industry, our findings in this research could improve the decision making regarding technology selection, as well as help with the operationalization of RFID and transformation to intelligent precast construction management in big data environment.     

Comparative study of structural material quantities of high‐rise residential buildings

A major factor in the selection of the structural system for a high‐rise building is the initial construction cost of candidate structural systems. In Korea, composite steel and concrete construction, and cast‐in‐place concrete flat plate construction are the most commonly used structural systems. However, there is a lack of data related to the relative construction costs of these two structure types. This paper compares material quantities for representative building models up to 80 stories in height using both types of structural system. Based on a typical floor plan, six models are developed and the buildings are designed for gravity and lateral loading. Quantities of materials for each model are calculated and compared. The information presented can be used with appropriate cost data to compare construction costs for the two structural system types. Copyright © 2007 John Wiley & Sons, Ltd.     

Time‐dependent analysis of steel‐reinforced concrete structures

The time‐dependent behavior is a major consideration in the design and construction of tall buildings, especially in concrete and composite structural systems. To make an analysis of long‐term effect of steel‐reinforced concrete structures, the method of using master–slave constraint to deduce substructure element model of composite members was introduced, and the problem of co‐work between steel and concrete was solved. The creep calculation method of combined Age‐adjusted Effective Modulus Method (AEMM) and finite element method was adopted. Steel Reinforced Concrete Construction Modeling (SRCCM), a calculation program based on Visual C++ and ObjectARX, was developed for simulating the construction process of high‐rise composite structures. The use of the method is illustrated through one computation example of Shanghai Center Tower, which is a super high‐rise steel‐reinforced concrete structures. The method provides valuable information about time effects that may be used in designing new structures or in diagnosis existing structures. The results also indicate that the vertical shortening of Shanghai Center Tower between column and core‐tube is significant. Such differential length changes should be compensated during the construction process of high‐rise composite structures. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of a Data‐Driven Framework for Real‐Time Travel Time Prediction

Travel time prediction is one of the most important components in Intelligent Transportation Systems implementation. Various related techniques have been developed, but the efforts for improving the applicability of long‐term prediction in a real‐time manner have been lacking. Existing methods do not fully utilize the advantages of the state‐of‐the‐art cloud system and large amount of data due to computation issues. We propose a new prediction framework for real‐time travel time services in the cloud system. A distinctive feature is that the prediction is done with the entire data of a road section to stably and accurately produce the long‐term (at least 6‐hour prediction horizon) predicted value. Another distinctive feature is that the framework uses a hierarchical pattern matching called Multilevel k‐nearest neighbor (Mk‐NN) method which is compared with the conventional k‐NN method and Nearest Historical average method. The results show that the method can more accurately and robustly predict the long‐term travel time with shorter computation time.     

VFT‐WIB‐Brücke bei Vigaun – Verbundbrücke mit externer Bewehrung

VFT‐WIB viaduct in Vigaun – a composite bridge with external reinforcement. With the introduction of the composite dowel the possibility is given to develop new construction methods for bridges. The VFT‐WIB construction method is used for the first time for the road bridge in Vigaun/Austria, which is in service since autumn 2008. The cross‐section is composed out of two prefabricated elements with halved rolled girders, working as bottom flange. The composite dowels are manufactured by cutting the rolled girder into two halves with a special cutting‐line. These halved girders work as external reinforcement, which leads to very slender and economical composite structures. Below details about the planning process, the design and the construction process of 78m long three span framing bridge over the railway line from Salzburg to Wörgl are shown.     

Hermann‐Liebmann‐Brücke in Leipzig – Herstellung mit Spannverbund‐Trägern in geteilter Bauweise

Hermann‐Liebmann Bridge in Leipzig – Construction method with Spannverbund‐Girder. The Hermann‐Liebmann bridge is a five‐span road bridge over railway tracks in the city centre of Leipzig. It is built as a prestressed double composite bridge. Taking into account the traffic on and under the bridge, the demolition of the existing bridge has got decisive influence on the conception of its replacement. Deck structures on both sides of the existing bridge were erected first and served as the platforms to remove the old steel construction, to supply the construction site, and to constantly keep open the bridge for pedestrian traffic. This way, the ambitious bridge project could be realized reducing restrictions for the railway traffic to a minimum.     

ResCol‐Versuche zur Prüfung der dynamischen Langzeitstabilität von TA/TM‐Böden unter Eisenbahnverkehr

Application of resonant column tests for the investigation of the dynamic long‐term stability of clays under railway traffic. Some resonant column tests have been done on the clays, which were taken from the foundation zones of open cut in the new railway line Nuremberg–Ingolstadt (under construction). From the tests, basic dynamic parameters were determined for the evaluation of dynamic long‐term stability of railway foundation by using a new approach, which has been developed by using well‐known soil dynamic knowledge. With the help of the test results, the practical controlling criteria in regard to the long‐term dynamic stability have been derived for construction site. In the paper presented, the design criterion, the test results and their application in practice are described.     

Creep and shrinkage analysis of reinforced concrete frames by history‐adjusted and shrinkage‐adjusted elasticity moduli

Consideration of the time‐dependent deformations due to creep and shrinkage is often necessary to ensure satisfactory behavior of complex concrete structures. The stresses and deformations of a reinforced concrete frame can be analyzed by the finite element method using time integration. However, as the full stress history prior to each time interval considered is necessary, with the increase in the number of time intervals used, the amount of computations increases dramatically. The concept of age‐adjusted elasticity modulus is further explored to develop new functions for efficient evaluation of time‐dependent behavior of concrete frames. The history‐adjusted elasticity modulus is devised so that stage construction can be modeled more accurately. Likewise, the shrinkage‐adjusted elasticity modulus is introduced to enable shrinkage analysis to be carried out using one single step. The methods can cope with frame structures built and loaded in several stages. Accurate results can be obtained by considering just a few large time intervals instead of those fine time steps used in time integration. Numerical examples are presented to demonstrate the usefulness of the new methods. Copyright © 2007 John Wiley & Sons, Ltd.     

Agglomeration and firm‐level productivity: A Bayesian spatial approach

This paper estimates the impact of industrial agglomeration on firm‐level productivity in Chinese manufacturing sectors. To account for spatial autocorrelation across regions, we formulate a hierarchical spatial model and use a Bayesian instrumental‐variable approach. We find that agglomeration of the same industry (i.e., localization) has a productivity‐boosting effect, but agglomeration of urban population (i.e., urbanization) has no such effect. In addition, the localization effect increases with the educational levels of employees and the share of intermediate inputs in gross output. These results may suggest that agglomeration externalities occur through knowledge spillovers and input sharing among firms producing similar manufactures.     

A Natural‐Language‐Based Approach to Intelligent Data Retrieval and Representation for Cloud BIM

As the information from diverse disciplines continues to integrate during the whole life cycle of an Architecture, Engineering, and Construction (AEC) project, the BIM (Building Information Model/Modeling) becomes increasingly large. This condition will cause users difficulty in acquiring the information they truly desire on a mobile device with limited space for interaction. The situation will be even worse for personnel without extensive knowledge of Industry Foundation Classes (IFC) or for nonexperts of the BIM software. To improve the value of the big data of BIM, an approach to intelligent data retrieval and representation for cloud BIM applications based on natural language processing was proposed. First, strategies for data storage and query acceleration based on the popular cloud‐based database were explored to handle the large amount of BIM data. Then, the concepts “keyword” and “constraint” were proposed to capture the key objects and their specifications in a natural‐language‐based sentence that expresses the requirements of the user. Keywords and constraints can be mapped to IFC entities or properties through the International Framework for Dictionaries (IFD). The relationship between the user's requirement and the IFC‐based data model was established by path finding in a graph generated from the IFC schema, enabling data retrieval and analysis. Finally, the analyzed and summarized results of BIM data were represented based on the structure of the retrieved data. A prototype application was developed to validate the proposed approach on the data collected during the construction of the terminal of Kunming Airport, the largest single building in China. The case study illustrated the following: (1) relationships between the user requirements and the data users concerned are established, (2) user‐concerned data can be automatically retrieved and aggregated based on the cloud for BIM, and (3) the data are represented in a proper form for a visual view and a comprehensive report. With this approach, users can significantly benefit from requesting for information and the value of BIM will be enhanced.     

Internal force monitoring and estimation of a long‐span ring beam using long‐gauge strain sensing

The internal force information of curved beam members is important evidence for the stress state evaluation and design verification of long‐span space structure during construction. Many structural analysis methods for curved beams have been proposed, but most are used to handle the complex geometric shapes. For stress state evaluation of long‐span steel‐concrete composite (SCC) ring beam, this article presents a method that employs a sectional strain distribution model (SSDM) and a fiber model to estimate the internal force distribution depending on the long‐gauge strain. The SSDM of the ring beam used in the article is based on a mechanical model of two‐dimensional (2‐D) plane bending deformation and a three‐dimensional (3‐D) solid finite element model of curved beam members. The application range of the SSDM is defined by the divided different stress areas of ring beam based on the 3‐D solid finite element model. Combined with the established SSDM and the different stress areas, the axial force and bending moment along the span are then identified separately based on the fiber model. In consideration of field monitoring, the influence of different sensor layout on the establishment of SSDM and the result of internal force identification is discussed. The results of the numerical studies show that the proposed methodology can identify the internal force distribution accurately. Internal force of long‐span ring beam from Jiangsu Grand Theater during construction is also identified through the proposed method by using the strain monitoring data.     

Ermittlung des Aufbaus und der Stoffkennwerte von Außenbauteilen mit Hilfe von In‐situ‐Messungen und FEM‐Berechnungen

Determination of the construction and the material identity values of outside building components with the help of in‐situ measuring procedures and FEM‐simulation calculations. The aims formulated nationwide and internationally to the climate protection can be achieved by combining of the energy‐efficient construction and rehabilitation of the existing buildings. Knowledge about the construction and the material identity values of the warmth‐transferring outside components is a condition for the energetic balance of buildings. The essential information to this can frequently be no more taken from the construction documents particularly for older buildings since they are no longer traceable or incomplete. At the example by univalve and bivalve out‐wall construction it is shown that the thermophysical qualities can be determined with the help of in‐situ measuring procedures and FE‐simulation calculations without destruction.     

A Spatial‐Context‐Based Approach for Automated Spatial Change Analysis of Piece‐Wise Linear Building Elements

Changes of designs and construction plans often cause propagative design modifications, tedious construction coordination, cascading effects of errors, reworks, and delays in project management. Among various building elements, those having piece‐wise linear geometries (i.e., connected straight line segments), such as connected straight sections of ducts in mechanical, electrical, and plumbing systems, frequently undergo spatial changes in response to the changes of their surroundings. On the other hand, the piece‐wise linear geometries pose challenges to analyzing and controlling changes in construction and facility management. State‐of‐the‐art 3D change detection algorithms often face ambiguities about which points belong to which objects when piece‐wise linear object are spacked in small spaces. This article examines a spatial‐context‐based framework that uses spatial relationships between piece‐wise linear building elements (ducts in this article) to enable fast and reliable association of 3D data with ducts in as‐designed models for supporting reliable change analysis. Three case studies showed that this framework outperformed a conventional change detection method, and could handle large dislocations of piece‐wise linear elements and occlusions.     

Analyse des Gefüge‐ und Feuchtezustandes in mineralischen Baustoffen mit der Mikro‐Röntgen‐3D‐Computertomografie

Condition Assessment of Microstructure and Moisture Distribution in Mineral Building Materials by Micro X‐Ray Computed Tomography. The knowledge of microstructure and moisture condition in capillary porous building materials is essential for building climate control and building durability. The 3D X‐ray computed tomography (3D‐CT) opens up new vistas for the visualization of both parameters. In this article the performance of this innovative non‐destructive testing method is demonstrated by means of two studies showing its feasibility. The first feasibility study was carried out with a drilling core taken from a fair‐faced concrete cladding which was strongly damaged by freeze‐thaw cycling. The 3D‐CT investigations have shown that it is possible to visualize the crack and moisture distribution especially interesting besides the spatial distribution of aggregates and hardened cement paste. So the method opens up new vistas for the tracing of interactions between cracks due to frost and moisture distribution without any destructive interventions. This can help to clarify the damage mechanisms in concrete due to frost which are partly not sufficient known up to now. Objective of the second feasibility study was to demonstrate not only the spatial but also the temporal distribution of the moisture in tuff during the capillary water absorption test. The 3D‐CT investigations have shown that the spatial motion of the capillary moisture front with delayed water absorption of pumice, a magmatic tuff component, can be visualized. Based on these studies this article finally shows the next steps which are necessary to improve the performance of the test method.     

Schrägseilbrücke für Straßenbahn‐, Geh‐ und Radverkehr

Cable‐stayed bridge for tramway, pedestrians, and bike traffic. For the development of the new quarter “Parkstadt Schwabing” in den North of Munich, the transport connection is established by a new tramway, the line 23. Thereby, a new bridge construction became necessary for the crossing of the main circular roadway “Mittlerer Ring” at the Schenkendorfstraße. The extraordinary bridge structure in direct conjunction with the glass enclosure of the Petuel‐tunnel belongs to the most spectacular metropolitan crossing locations of Munich.