Estimation of Live Load Distribution Factor for a PSC I Girder Bridge in an Ambient Vibration Test

Maintenance of bridges in use is essential and measuring the live load distribution factor (LLDF) of a bridge to examine bridge integrity and safety is important. A vehicle loading test has been used to measure the LLDF of a bridge. To carry this out on a bridge in use, traffic control is required because loading must be performed at designated positions using vehicles whose details are known. This makes it difficult to measure LLDF. This study proposed a method of estimating the LLDF of a bridge using the vertical displacement response caused by traveling vehicles under ambient vibration conditions in the absence of vehicle control. Since the displacement response measured from a bridge included both static and dynamic components, the static component required for the estimation of LLDF was extracted using empirical mode decomposition (EMD). The vehicle loading and ambient vibration tests were conducted to verify the validity of the proposed method. It was confirmed that the proposed method can effectively estimate the LLDF of a bridge if the vehicle type and driving lane on the bridge are identified in the ambient vibration test.

Load Distribution in Precast Wide-Flange CPCI Girder Bridges

As Ontario bridge infrastructure enters the era of maintenance, rehabilitation and replacement, prefabricated bridge systems will certainly have many advantages as compared to the conventional systems. Prefabricated systems can be quickly assembled and the traffic can be opened in a very short period of time, minimizing the lane closure time, reducing the cost and design time, and minimizing forming and labour work. The Canadian Highway Bridge Design Code specifies simplified design method for slab-on-girder bridges in the form of moment and shear distribution factors. This thesis presents a parametric study, using the finite-element method, on a series of precast Wide-Flange CPCI girder bridges to examine the applicability of the CHBDC load distribution factors to this prefabricated bridge system. The parameters considered in this study include span length, number of lanes, number of girders, live load conditions, presence of intermediate diaphragms, and type of connections between individual girders. This study revealed that CHBDC load distribution factors generally overestimate the structural response of such bridges. As a result, a refined set of load distribution factor equations were developed.

Load Distribution in Precast Wide-Flange CPCI Girder Bridges

As Ontario bridge infrastructure enters the era of maintenance, rehabilitation and replacement, prefabricated bridge systems will certainly have many advantages as compared to the conventional systems. Prefabricated systems can be quickly assembled and the traffic can be opened in a very short period of time, minimizing the lane closure time, reducing the cost and design time, and minimizing forming and labour work. The Canadian Highway Bridge Design Code specifies simplified design method for slab-on-girder bridges in the form of moment and shear distribution factors. This thesis presents a parametric study, using the finite-element method, on a series of precast Wide-Flange CPCI girder bridges to examine the applicability of the CHBDC load distribution factors to this prefabricated bridge system. The parameters considered in this study include span length, number of lanes, number of girders, live load conditions, presence of intermediate diaphragms, and type of connections between individual girders. This study revealed that CHBDC load distribution factors generally overestimate the structural response of such bridges. As a result, a refined set of load distribution factor equations were developed.

LOAD DISTRIBUTION FACTOR ALONG THE POWER TRANSMISSION LINE AS A FACTOR IN CHOOSING A VOLTAGE CLASS

Газовые месторождения отличаются от промышленных предприятий протяженными линиями электропередачи с небольшими электрическими нагрузками (низкой плотностью), которые многократно растут в процессе жизненного цикла. Электроснабжение кустов газовых скважин осуществляется по схеме - «магистральная схема с одной сквозной магистралью с трансформаторными подстанциями, распределёнными по линии». Распределение трансформаторных подстанций по линии электропередачи влияет на потерю напряжения, а, следовательно, и выбор класса напряжения. Цель исследования заключается в количественной оценке распределения трансформаторных подстанций по линии электропередачи для разработки математической модели расчета оптимального класса напряжения. Для достижения поставленной цели в работе решаются следующие задачи: строятся пять схем электроснабжения кустов газовых скважин; рассчитываются электрические моменты для каждой схемы; определяется коэффициент распределения нагрузки. Решение задач в работе выполнено с помощью экспериментально-теоретического метода (анализ и синтез) и программного продукта - Mathcad. В результате в работе рассчитан коэффициент - при равномерном распределении нагрузки, при размещении всей нагрузки в конце линии и при размещении нагрузки в начале линии.

Experimental evaluation of the lateral load distribution in the elastic-plastic phase of timber-steel hybrid structures with a novel light timber-steel diaphragm

A cyclic loading experiment involving a timber-steel hybrid structure consisting of a steel frame and a novel light timber-steel diaphragm is presented to quantify the flexibility of the diaphragm and its ability to distribute lateral loads in the elastic-plastic phase of the structure. A lateral load-distribution factor was proposed, and its relationship to the ratio of the stiffness of the diaphragm to that of the lateral load-resisting elements was investigated. The diaphragm was classified based on these variables. The results indicated that the failure modes of the structure were associated with the forms of damage experienced by the lateral load-resisting elements, whereas little damage was observed for the diaphragm. The diaphragm exhibited the ability to continuously adjust the distribution of lateral loads to each lateral load-resisting element; accordingly, each lateral load-resisting element had approximately the same shear force, the same lateral stiffness, and the same lateral displacement during the loading process. As the lateral displacement increased, the stiffness ratio and load-distribution factor both gradually increased, and the diaphragm correspondingly changed from semi-rigid to rigid. At times, as the lateral displacement increased, the diaphragm rapidly became rigid, and it was unnecessarily rigid during the initial loading phase when the in-plane stiffness reached a certain threshold.