Abstract: Past studies have demonstrated that the vertical earthquake component can substantially affect the seismic performance of bridges and buildings. This component is typically ignored or, when included in the design, is estimated as two-thirds of the horizontal seismic design earthquake. This paper presents the characterization of the acceleration amplitude of the vertical component of moderate and strong earthquakes in Colombia (Moment magnitude Mw > 4) that occurred between June 1993 and April 2020. A total of 42 seismic records registered at less than 50 km from the rupture plane and with horizontal acceleration peaks greater than 0.05g were selected. The peak ground acceleration (PGA) of the three components and the ratio between those PGAS were calculated. Additionally, the relationship among those parameters and the magnitude and epicentral and hypocentral distances were determined. The results showed that the V/H ratio equal to 2/3 is not always valid to represent the effects of the vertical component in structures subjected to the moderate and strong ground motions in Colombia.

Resumen: Estudios anteriores han demostrado que el componente vertical del terremoto puede afectar sustancialmente el desempeño sísmico de puentes y edificios. Este componente generalmente se ignora o, cuando se incluye en el diseño, se estima como dos tercios del terremoto de diseño sísmico horizontal. Este trabajo presenta la caracterización de la amplitud de aceleración del componente vertical de sismos moderados y fuertes en Colombia (Magnitud de momento Mw > 4) ocurridos entre junio de 1993 y abril de 2020. Se registraron un total de 42 registros sísmicos a menos de 50 km del Se seleccionaron planos de ruptura y con picos de aceleración horizontal mayores a 0.05g. Se calcularon la aceleración máxima del suelo (PGA) de los tres componentes y la relación entre esos PGA. Adicionalmente, se determinó la relación entre dichos parámetros y la magnitud y las distancias epicentral e hipo central. Los resultados mostraron que la relación V/H igual a 2/3 no siempre es válida para representar los efectos del componente vertical en estructuras sometidas a movimientos de suelo moderados y fuertes en Colombia.

Abstract Intermediate diaphragms (ID) in bridges with precast girders are intended to improve load distribution among girders. Despite this, their efficacy has been doubted recently due to the complex construction tasks needed to join them to the girders. Accordingly, this work aimed to determine the effect of the number of IDs on the distribution of vertical loads and girders response of a simply supported bridge. Four bridge layouts (0, 1, 2, and 3 IDs) were analyzed using 3D computational grillage models. The load distribution factors from the models were compared to those calculated using the Engesser-Courbon and Fauchart methods to determine the latter’s accuracy in capturing the effect of the number of IDs. Moreover, the girders responses under the live loads in the current Colombian and Brazilian bridge design codes were assessed. The results show that the IDs have a more significant effect on the load distribution and deflection of interior girders than the exterior girders. Additionally, increasing the number of IDs reduced the maximum shear and torque while the bending moment and deflections remained nearly constant.